Efficiency Investigation of a Helical Turbine for Harvesting Wind Energy

Transcription

1 Efficiency Investigation of a Helical Turbine for Harvesting Wind Energy A Thesis presented by Nathan Willard To The Department of Mechanical and Industrial Engineering In partial fulfillment of the requirements For the degree of Master of Science In Mechanical Engineering In the field of Thermofluids Engineering Northeastern University Boston, Massachusetts September 2011

2 Abstract In recent times, there has been an increased interest in wind energy due to concerns about the pollution caused by burning fossil fuels and their rising prices. Most wind turbines in use today are conventional wind mills with three airfoil shaped blades arraigned around a horizontal axis. These turbines must be turned to face into the wind and in general require significant air velocities to operate. Another style of turbine is one where the blades are positioned vertically or transverse to the axis of rotation. These turbines will always rotate in the same direction regardless of the fluid flow. Due to the independence from the direction of the fluid flow, these turbines have found applications in tidal and surface current flows. To see how effective this sort of turbine would be in air, a helical turbine based on the designs and patents of Dr. Alexander M. Gorlov was chosen. His turbine was developed to improve upon the design of Georges J. M. Darrius by increasing the efficiency and removing pulsating stresses on the blades, caused by the blades hitting their aerodynamic stall in the course of rotation, which often resulted in fatigue failure in the blades or the joints that secured them to the shaft. The turbine takes the Darrius type turbine, which has a plurality of blades arranged transverse to the axis of rotation, and adds a helical twist to their path, insuring that regardless of the position of the turbine, a portion of the blade is always positioned in the position that gives maximum lift. This feature reduces the pulsations that are common in a Darrius type turbine. In his investigations, Gorlov claims that his turbine is significantly more efficient than Darrius and has achieved overall efficiencies between 30% and 35%. For this investigation, a helical turbine was tested inside and outside a wind tunnel using an electric generator (inside tests only) and a torque meter paired with a tachometer to measure the output power of the turbine and calculate its efficiency. In the end, the turbine did not come close to the claimed 30% efficiency, reaching at best an efficiency of around 0.35%. Further investigations should be made to determine why the results from this investigation were as low as they are. ii

3 Acknowledgements First, I would like to express my deep appreciation for my advisor; Prof. M. E. Taslim for guiding me through the process of conducting this investigation. I would also like to give special thanks to Jonathan Doughty and Kevin McCue for the aid that they have given me in the construction and testing of the turbine. Thirdly, I would like to give thanks to my colleagues, Mehdi Abedi, Nathaniel Rosso and Adebayo Adebiyi for the hints and tips they have given me through conversation regarding this investigation. Finally, I would like to express my gratitude to my family for supporting me in this endeavor. iii

4 Table of Contents Abstract... ii Acknowledgements... iii List of Figures... vi List of Tables... ix Nomenclature... xi Chapter Introduction Literature Review... 2 Chapter Overview of Experiment Design and Construction of the Turbine Overview of Design Shaft Design Flange Design Spoke Arm Design Blade Design Selection of Instrumentation Torque Meter Tachometer Generator Pitot Tube and Manometer Wind Meter Test Setup and Procedure Layout of the Test Chamber Wind Tunnel Tests Out of Wind Tunnel Tests Calibration Check on Handheld Wind Meter Chapter Wind Tunnel Tests with Generator Results from 0.55in Oil Test Results from 0.60in Oil Test Results from 0.65in Oil Test Results from 0.70in Oil Test Results from 0.75in Oil Test Results from 0.80in Oil Test iv

5 3.1.7 Results from 0.85in Oil Test Results from 0.90in Oil Test Results from 0.95in Oil Test Results from 1.0in Oil Test Rotational Velocity Results Turbine Power Results Turbine Efficiency Results Wind Tunnel Tests with Torque Meter Out of Wind Tunnel Test with Torque Meter Fan 12in from Turbine Fan 24in from Turbine Conclusions Further Investigations Works Cited Appendix A: Technical Drawings of Turbine Appendix B: Raw Data Appendix C: Calibration Information v

6 List of Figures Figure 1-1: Figure 3 from Darrius' Patent for his Turbine. (1)... 2 Figure 2-1: Exploded View of Turbine Assembly... 7 Figure 2-2: Flange Design... 9 Figure 2-3: Spoke Arm Design... 9 Figure 2-4: NACA0018 Airfoil Profile Figure 2-5: Top View of Turbine Blade Figure 2-6: Side View of Turbine Blade Figure 2-7: Blade Half Figure 2-8: Himmelstein Torque Meter Figure 2-9: LED Tachometer Figure 2-10: Generator Figure 2-11: Kestrel Wind Meter Figure 2-12: Test Chamber Layout, Top Down View and Side View Figure 2-13: Torque Meter Configuration Figure 2-14: Generator Set Up Figure 2-15: Out of Wind Tunnel Set Up Figure 3-1: Rotational Velocity at 0.55in Oil Figure 3-2: Output Power at 0.55in Oil Figure 3-3: Efficiency at 0.55in Oil Figure 3-4: Rotational Velocity at 0.6in Oil Figure 3-5: Output Power at 0.6in Oil Figure 3-6: Efficiency at 0.6in Oil Figure 3-7: Rotational Velocity at 0.65in Oil Figure 3-8: Output Power at 0.65in Oil vi

7 Figure 3-9: Efficiency at 0.65in Oil Figure 3-10: Rotational Velocity at 0.7in Oil Figure 3-11: Output Power at 0.7in Oil Figure 3-12: Efficiency at 0.7in Oil Figure 3-13: Rotational Velocity at 0.75in Oil Figure 3-14: Output Power at 0.75in Oil Figure 3-15: Efficiency at 0.75in Oil Figure 3-16: Rotational Velocity at 0.8in Oil Figure 3-17: Output Power at 0.8in Oil Figure 3-18: Efficiency at 0.8in Oil Figure 3-19: Rotational Velocity at 0.85in Oil Figure 3-20: Output Power at 0.85in Oil Figure 3-21: Efficiency at 0.85in Oil Figure 3-22: Rotational Velocity at 0.9in Oil Figure 3-23: Output Power at 0.9in Oil Figure 3-24: Efficiency at 0.9in Oil Figure 3-25: Rotational Velocity at 0.95in Oil Figure 3-26: Output Power at 0.95in Oil Figure 3-27: Efficiency at 0.95in Oil Figure 3-28: Rotational Velocity at 1in Oil Figure 3-29: Output Power at 1in Oil Figure 3-30: Efficiency at 1in Oil Figure 3-31: Rotational Velocity of the Turbine Across all Wind Velocities Figure 3-32: Percent Error Figure 3-33: Output Power from Generator and Air Power Figure 3-34: Output Power Error vii

8 Figure 3-35: Efficiency Figure 3-36: Output Power of Turbine using the Torque Meter and Generator Figure 3-37: Rotational Velocity, Torque Meter vs. Generator Figure 3-38: Torque from Tests Taken with Fan 12in from Turbine Figure 3-39: Rotational Velocity Taken from Tests with Fan 12in from Turbine Figure 3-40: Output Power Calculated from Tests Taken with Fan 12in from Turbine Figure 3-41: Efficiency Calculated from Tests Taken with Fan 12in from Turbine Figure 3-42: Torque Taken from Tests with Fan 24in from Turbine Figure 3-43: Rotational Velocity from Tests Taken with Fan 24in from Turbine Figure 3-44: Output Power Calculated from Tests Taken with Fan 24in from Turbine Figure 3-45: Efficiency Calculated from Tests Taken with Fan 24in from Turbine Figure A-1: Dimensioned Drawing for Turbine Shaft Figure A-2: Dimensioned Drawing of the Flanged Shaft Mount for the Turbine Figure A-3: Dimensioned Drawing of the Spoked Arm Wheel for the Turbine Figure A-4: Dimensioned Drawing of the Top Half of the Turbine Blade Figure A-5: Dimensioned Drawing of Bottom Half of the Turbine Blade Figure C-1: Torque Meter Calibration Sheet Figure C-2: Torque Meter Spec Sheet Figure C-3: Tachometer Spec Sheet Side Figure C-4: Tachometer Spec Sheet Side viii

9 List of Tables Table 2-1: Expected Torque Values Table 2-2: Wind Meter Calibration at 0.85in Oil Table 3-1: Approximate Air Velocities in m/s Table B-1: In Wind Tunnel with Generator, 0.55in Oil Table B-2: In Wind Tunnel with Generator, 0.6in Oil Table B-3: In Wind Tunnel with Generator, 0.65in Oil Table B-4: In Wind Tunnel with Generator, 0.7in Oil Table B-5: In Wind Tunnel with Generator, 0.75in Oil Table B-6: In Wind Tunnel with Generator at 0.8in Oil Table B-7: In Wind Tunnel with Generator at 0.85in Oil Table B-8: In Wind Tunnel with Generator at 0.9in Oil Table B-9: In Wind Tunnel with Generator at 0.95in Oil Table B-10: In Wind Tunnel with Generator at 1in Oil Table B-11: In Wind Tunnel with Generator Averages Table B-12: In Wind Tunnel with Torque Meter, Test Table B-13: In Wind Tunnel with Torque Meter, Test Table B-14: In Wind Tunnel with Torque Meter, Test Table B-15: Out of Wind Tunnel with Torque Meter at 12in, Test Table B-16: Out of Wind Tunnel with Torque Meter at 12in, Test Table B-17: Out of Wind Tunnel with Torque Meter at 12in, Test Table B-18: Out of Wind Tunnel with Torque Meter at 12in, Test Table B-19: Out of Wind Tunnel with Torque Meter at 24in, Test Table B-20: Out of Wind Tunnel with Torque Meter at 24in, Test Table B-21: Out of Wind Tunnel with Torque Meter at 24in, Test ix

10 Table B-22: Out of Wind Tunnel with Torque Meter at 24in, Test Table C-1: Wind Meter Calibration at 0.425in Oil Table C-2: Wind Meter Calibration at 0.5in Oil Table C-3: Wind Meter Calibration at 0.65in Oil x

11 Nomenclature A Pr : Projected area of the turbine I: Current P: Pressure P atm : Atmospheric Pressure P T : Power from Turbine P W : Wind Power R: Resistance T: Torque V: Voltage V W : Wind Velocity P: Pressure Difference η: Efficiency ρ: Air Denisty ω: Rotational Velocity xi

12 Chapter Introduction Wind turbines are a growing area of interest in the energy market. With the push for the development of green energy sources to reduce our dependence on fossil fuels such as coal, natural gas and oil, major developments in the area of wind energy have been made in recent years. Many of the more well known applications for wind energy are for large scale electric generation, with the commonly seen three bladed turbines that can be seen in many windy areas. However, these types of turbines are not suited for applications where the turbine needs to be portable or operate in low air speed areas. Professor Alexander Gorlov developed a helical turbine designed for low fluid flow rates in the 1990 s. It was initially developed for use in water, either in a slow river or as a tidal generator. The turbine, which uses a vertical axis configuration, has three blades that are swept along a helical path. With this configuration, the turbine will always rotate in the same direction, regardless of the direction of the fluid flow. With its small size and intended use for low flow situations, Gorlov s helical turbine is a prime candidate to fill the need for a portable wind turbine. The efficiency of a turbine, the ratio of the output electrical power compared to the input wind power, is often used to determine how effective a given design is. The wind power can be determined using the projection area of the turbine and wind velocity, in the equation P W =0.5ρA Pr V 3 W 1

13 The efficiency of the turbine is defined as follows η=p T /P W 1.2 Literature Review Gorlov s helical turbine is based off the Darrius turbine which was invented in 1926 by G.J.M. Darrius and was patented in the US in 1931 (1). Darrius turbine is commonly seen with semi-circular blades with an airfoil cross section spaced evenly around then shaft with the ends of the blades meeting near each end of the shaft. A drawing of this common configuration, taken from his patent, can be seen below in Figure 1-1. In his patent, Darrius claims that his design is an improvement over previous transverse axis designs because his blades use airfoils which offer minimal resistance to forward movement in the fluid and thus converting the maximum amount of available energy in the fluid to usable energy by way of the shaft. Figure 1-1: Figure 3 from Darrius' Patent for his Turbine. (1) In his paper on the Limits of the Turbine Efficiency for Free Fluid Flow, Dr. Gorlov points out a weakness in Darrius design. He states that due to the vibrations cause by the blades changing their angle of attack during the rotation of the turbine, the turbine is prone to fatigue failure in its parts or joints (2). 2

14 Another invention that provided influence to Gorlov s design was a water wheel invented in 1902 by Austrian Gustav Marburg. While Marburg s claims and focus are on methods of allowing the water wheel to split, allowing a ship to pass through, it is stated that the blades have a spiral or helical turn to render them more effective (3). Unlike Darrius turbine, the blades on Marburg s water wheel are designed to harness the energy of the fluid through resistance, as opposed to lift. Gorlov s turbine combines the use of airfoils on a transverse axis turbine with the helical path inspired by the drawings of Marburg s water wheel. Dr. Gorlov has filed for two patents for his turbine. His turbine was first patented in 1995 and claimed to be a turbine with transverse airfoil blades in a helical configuration such that a portion of the blades were always perpendicular to the flow, maintaining maximum thrust and a constant rotational velocity (4). In the patent, hydro-pneumatic, hydro, wind and wave power systems are mentioned as sources of fluid flow suitable for this design. Furthermore, there are statements suggesting that for gas turbine applications under a low head pressure flow, the turbine can achieve similar rotational velocities to conventional industrial generators, but with a higher efficiency. The other patent filed for Gorlov s turbine is designed to protect additional uses for the technology that were not originally covered in the first filing. The focus of the second patent is for using the turbine to directly drive a propulsion system (5). This patent shows the versatility of the devise and its applications. Aside from directly driving a propulsion device, uses such as lift and lowering objects in a fluid are cited as well. 3

15 Dr. Gorlov also describes the advantages of his turbine in papers he published detailing some of his experimental results. In a paper published around the same time his patent on the turbine was granted, Dr. Gorlov describes the design in detail and results from tests he conducted. Among his claims and descriptions, he states that the power output will increase with the diameter of the turbine while the flow, the size and the shape of the blades remains the same (6). The paper also lists the results of two investigations. In all three, the helical turbine was compared to a Darrius type turbine. For the first investigation, the turbines were tested in conditions where there was a significant difference in elevation across the turbine. For that test, the Gorlov turbine was found to be 27 percent more efficient and to have a rotational velocity 41 percent faster than the Darrius turbine. The second investigation concerned the two turbines where they were only the velocity head was being extracted by the turbine. In this case, the Gorlov turbine was found to be 33 percent more efficient and 27 percent faster than the Darrius type. Dr. Gorlov goes on to claim that in low flow conditions that his turbine is 95 percent more efficient and 49 percent faster than Darrius (6). In Gorban et al., the turbine s unconstrained performance is claimed to be 35 percent (2). The paper itself focuses on mathematical models used to compute the performance of the turbine in a free flow situation. The maximal efficiency obtained from these calculations was and this is the number that formed the basis of my assumptions when selecting the instrumentation used for my investigations. In a paper written by Howell et al., a small Darrius type turbine was tested in a wind tunnel and compared to results from a computational model run in fluent. The primary purpose of this investigation was to verify the computational model and thus the turbine tested wasn t designed to necessarily the most 4

16 efficient, but to provide results that would be easy to measure, given their size constraints (7). The results illustrate the pulsating nature of the Darrius type turbine as described by Dr. Gorlov in his papers and patents regarding his helical turbine. The paper also concludes that the computational model and the physical tests were in reasonably good agreement, considering the errors and uncertainties involved in both the physical test and the computational model. In an article that appeared in the March 2009 issue of Environmental Engineering, author Niel Wilks gives an overview of research that was being conducted at the time exploring the noise of vertical axis turbines. He found that researchers were finding that turbines that follow the vertical or transverse axis design are quieter than the horizontal axis counterparts (8). Steven Peace, in an article that appeared in the June 2004 issue of ASME s Mechanical Engineering, argues that the future of wind turbines is with vertical axis designs, which the Darrius and Gorlov turbines both fall under. Peace argues that vertical axis turbines have fewer limitations than horizontal turbines and thus can be built to have larger swept areas and take advantage of larger input powers (9). 5

17 Chapter Overview of Experiment The goal of the experiment was to test a helical turbine in a controlled environment, measure the output power and compare that with the available wind power to find the efficiency of the turbine. To do this, two methods of measuring the turbines power were employed. The first consisted of using a torque meter to determine the output torque and a tachometer to measure the rotational velocity, in revolutions per second, of the turbine. The power would be calculated by the following relationship. P T =2πωT The second method used to determine the output power was as small generator powering a small resistor circuit. Using Ohm s Law, V=IR And the electrical power relationship, P T =VI The output power could be determined. P T =V 2 /R To calculate the air power over the projected area of the turbine, the air velocity was required. To measure the air velocity in the wind tunnel a pitot tube attached to an oil manometer was used. For tests done outside the wind tunnel, a hand held wind meter was used. 6

18 2.2 Design and Construction of the Turbine Overview of Design The turbine used for the experiments had to fit several criteria. The primary concern was making the turbine small enough to fit into the wind tunnel in Northeastern s Richard s Hall lab. The cross sectional area of the test chamber on this wind tunnel perpendicular to the air flow measures 18.5 inches wide by 14 inches tall. Furthermore, the opening in the side of the test chamber that I would use to put the turbine in measured 12 inches in diameter, so the turbine would also have to fit through that hole. With those constraints and allowing for clearance between the turbine and the walls to reduce their effects on the turbines performance, a projected area of 14 inches wide and 10 inches tall was settled on. An exploded view of the assembly can be seen below in Figure 2-1. Figure 2-1: Exploded View of Turbine Assembly The two other main concerns were cost and weight. Due to the relatively small sized of the turbine, I wanted to keep the turbine light to reduce losses and to use materials that were inexpensive. To accomplish this, the turbine was constructed using plastics for the spoke arms and blades, aluminum for 7

19 the flanges and steel for the shaft. All of the solid models and drawings required for the production of the turbine were created using SolidWorks Shaft Design The shaft of the turbine consists of a single two foot length of steel measuring 3/8ths of an inch in diameter. The use of steel over a lighter metal such as aluminum was based on the availability of materials on McMaster-Carr where I sourced many of the materials and parts I needed to purchase. The steel rod that was purchased for the shaft had a straightness tolerance of ±0.05 inches where none of the aluminum rods had a tolerance given Flange Design The flanges, as shown in Figure 2-2, are used to attach the spoke arms to the shaft were machined out of aluminum. The primary reason for these flanges being separate pieces instead of being part of the spoke arm was to reduce the amount of material required. The flanges have three bolt holes to attach them to the spoke arm and a single threaded hole for a set screw to secure them along with the spoke arm to the shaft. 8

20 Figure 2-2: Flange Design Spoke Arm Design The spoke arm component, shown in Figure 2-3, has three arms extending from the central hub of the part with extended sections at the end of the arms to attach the turbine blades. The leading edges of the arms were also rounded to reduce the drag of the arms. For material, ¼ inch polycarbonate was chosen and the parts were machined using a CNC machine. Figure 2-3: Spoke Arm Design 9

21 2.2.5 Blade Design The turbine blades are the most important part of this design. They are 14 inches long and follow a helical path with a 5 inch radius over a 60 degree arc. The cross section is a standard NACA 0018 air foil with a 1.5 inch chord. Since the airfoil is symmetric along the chord, the mean camber line follows the chord. The helical path that the blade follows is drawn along the midpoint of the camber line and the blade is set at a 0 degree angle of attack. The profile of the airfoil is shown in Figure 2-4. Figure 2-4: NACA0018 Airfoil Profile The blades were produced using a 3D printer that built the blades up a layer at a time with ABS plastic. Due to the size constraints of the printer, the blades had to be cut in half and then assembled. The assembly was done with a combination of plastic cement and pins to strengthen the joint. Additionally, the joint was cut in a step shape to increase the surface area for bonding. While the glue and pins created a strong joint, the bending stresses on the blades during operation would be centered on the joint area due to the distance from the supports. The blades were further reinforced with fiber glass sleeves and epoxy, resulting in a stiff blade that showed no visible deformation during testing. 10

22 Figure 2-5: Top View of Turbine Blade Figure 2-6: Side View of Turbine Blade Figures 2-5 and 2-6 show the top and side views of the turbine respectively. The top view illustrates the arc of the helix that the blade follows while the side view shows the angle and the location of the join where the two blade halves meet. The pitch and radius of the helix was determined by the projected area of the turbine, which is the area in which the flow of the fluid interacts with the turbine. This area is the determined by the length and diameter of the turbine, in this case being 140in 2. Figure 2-7 shows a close up of a single blade half, detailing the step design of the cut. 11

23 Figure 2-7: Blade Half 2.3 Selection of Instrumentation Torque Meter The torque meter selected for the testing was the Himmelstein model MCRT-48201V(25-0) (shown in Figure 2-8). The meter is designed for a maximum of 2.82Nm of torque and was selected using an expected power output based on the efficiency claims made by Professor Gorlov. Table 2-1: Expected Torque Values Air Rotational Air Expected Expected Expected Velocity Velocity Power Efficiency Output Torque (m/s) (RPM) (W) (W) (Nm)

24 As shown in Table 2-1, the expected torque output ranges from 0.077Nm to 1.479Nm depending on the air velocity. The rotational velocities used were very rough estimates, since there were no previous tests of this turbine conducted in air to base them on. The expected torque ranges up to around half of the maximum torque the meter could handle. To get a torque meter with a lower maximum torque would have required going to their low range line of meters, which were considerably more expensive than meter used. Even then, the highest capacity of them, the 2.825Nm model, would have to have been chosen, since the next size down had a maximum torque rating of 1.412Nm, which is lower than the maximum torque expected. Figure 2-8: Himmelstein Torque Meter The Himmelstein torque meter operates by measuring the change in resistance of strain gauges applied to the shaft of the meter. The meter comes with software for use with the RS-232 output, or the output can be read as analog with either a ± 5V or ± 10V signal. The computer software will convert the voltage 13

25 output into units chosen by the user. It also has options to record the data as well as tare and calibrate the meter Tachometer To measure the rotational velocity of the turbine, an LED tachometer was chosen. The device operates by illuminating an LED and sends an electronic pulse every time the light from the LED is reflected back onto the photo sensor. The pulses were counted and displayed in Hz on an oscilloscope. Figure 2-9: LED Tachometer Since a piece of the reflective material was placed on each blade, the oscilloscope will show three pulses per revolution of the turbine (RPS times 3) Generator For the direct electrical power measurements, a small bicycle generator was used. The generator chosen was rated at 3 Watts and 6V, due to early test results showing poor performance. The generator was connected to power a simple circuit consisting of a 10 ohm resistor. The voltage drop across the resistor was measured to calculate the power. 14

26 Figure 2-10: Generator Pitot Tube and Manometer To measure the air velocity in the wind tunnel, a pitot tube connected to a manometer. The manometer used consists of a vertical tube and a reservoir containing oil with a specific gravity of Behind the tube is a ruler in inches that can be moved to zero the manometer. The top of the manometer tube is open to the atmosphere, so the pressure difference read is, P = P - P atm Wind Meter To measure the air velocity when testing outside the wind tunnel, a Kestrel 1000 Wind Meter was used. This meter uses an impeller mounted on the unit to measure the air velocity, which is displayed digitally on a screen in units of the users choosing. To get a reading, the user must simply hold the meter in the flow and read the output. 15

27 Figure 2-11: Kestrel Wind Meter 2.4 Test Setup and Procedure Layout of the Test Chamber The test chamber of the wind tunnel is 23 inches from entrance to exit, 18.5 inches wide and 14 inches tall. In each corner there is a curved piece of plastic that serves as a diffuser for the two placed near the entrance and as a nozzle for the two placed near the exit of the test chamber. On the left side of the chamber when facing the direction of the airflow, there is a small hole cut into the wall which is covered by a plastic plate from the outside. One of the bearings for the turbine was inserted into the plate. The other bearing was inserted into the door panel that covers the much larger hole cut into the right side of the test chamber. Along the top of the chamber is a long cut out for the pitot tube assembly, which is on a track mechanism that allows the pitot tube to be positioned anywhere along the length of the chamber at almost any height. The tube is limited, however, to the center of the width. In the center of the bottom plate, there is a small hole, into which the LED tachometer was mounted, pointing directly up. An overhead view of the test chamber with its inlet, outlet, diffuser and nozzle, and a side view can be seen in Figure

28 Figure 2-12: Test Chamber Layout, Top Down View and Side View Outside the test chamber a tripod with a bracket for mounting the torque meter was positioned in such a way that when the torque meter was mounted on the bracket, the shaft of the torque meter would be in line with the shaft of the turbine. For the tests involving the generator, the bracket and tripod was used along with a block of wood and some nylon cord to secure the generator in place Wind Tunnel Tests For the wind tunnel tests, the turbine is supported on each end by bearings set into the walls of the wind tunnel. The pitot tube was positioned in front of the turbine in the center of the plane perpendicular to the air flow. Reflective tape was placed on the blades of the turbine and the tachometer was mounted in a hole on the bottom of the test chamber, pointing up at the turbine. For the measurements taken with the torque meter, the meter was mounted on a tripod and coupled to the shaft of the turbine and a 50g weight was hung over a pulley placed on the torque meters shaft to provide 17

29 some resistance. Figure 2-13 shows the turbine in the wind tunnel with the torque meter mounted on the tripod. Also visible is the LED tachometer extending from the bottom of the test chamber. chamber Figure 2-13: Torque Meter Configuration For the measurements taken with the generator, as can be seen in Figure 2-14, the generator was coupled directly to the shaft of the turbine. The 10 ohm resistor was connected in a circuit with the generator and the probes from the oscilloscope where attached on either side of the resistor. Figure 2-14: Generator Set Up 18

30 For the generator tests, the air flow in the wind tunnel was set to a steady velocity and the system was allowed to come to a steady state. Once this state was reached, ten readings of the air velocity, rotational velocity and output torque or voltage were taken with 3 minutes in between each reading. Also noted was the ambient temperature and atmospheric pressure at the beginning of the test. This was repeated for multiple air velocities. For the tests with the torque meter, only a few ramp ups were performed before it was concluded that the generator was going to yield better results in the wind tunnel. The ramp ups were chosen for these tests due to the observation that for every test, the tare value to zero the torque meter was different and the output of the torque meter was different, even for the same settings. For the ramps, the test was started at a low air velocity and the turbine was allowed to stabilize. Once it reached a steady rotational velocity, a reading was taken and the air velocity was then increased to the next air velocity and the turbine was allowed to stabilize again Out of Wind Tunnel Tests For the tests outside of the wind tunnel, the turbine was mounted between two tables of equal heights with the bearings set into blocks of wood. The tachometer was mounted to the top of one of the blocks and reflective tape was placed on the spoke arms of the turbine. For this setup, only the torque meter was used and it was coupled directly to the turbine shaft with the same 20g weight over the pulley as the tests inside the wind tunnel. The torque meter itself rested on the table used to support one of the mounting blocks for the turbine. To provide air flow, a large fan was placed in front of the test rig and the handheld wind meter was used to take velocity readings. The set up is illustrated in Figure

31 Figure 2-15: Out of Wind Tunnel Set Up Similar to the in wind tunnel tests, the system was allowed to stabilize and then 10 readings were taken with an interval of 3 minutes between each reading. Since the fan used to provide the air flow only had one speed, the test was repeated with the fan at varying distances from the turbine. The turbine was tested with the fan 12in and 24in, measured from the screen on the front of the fan to the shaft of the turbine, away Calibration Check on Handheld Wind Meter Since the handheld wind meter used for the tests outside the wind tunnel didn t come with any calibration documentation, its accuracy was tested by comparing readings taken from it and the manometer at the same time in the same flow. To do this, the wind meter was mounted in the wind tunnel with the impeller as close to the pitot tube as possible. They were positioned in the center of the wind tunnel. Multiple readings were taken at each air velocity over a period of time. 20

32 Table 2-2: Wind Meter Calibration at 0.85in Oil Temperature 26 Atmospheric Pressure (in Hg) SG Oil Air Density (kg/m^3) Reading Wind Meter Manometer M. Speed Percent # m/s (in Oil) (m/s) Error Average The check was done at four different air speeds and it was found that the hand held wind meter did give accurate readings. Table 2-2 shows the results from the test done at 0.85in oil in the manometer. The rest of the calibration data can be seen in Appendix C. This test showed the smallest difference between the manometer and the wind meter of the four tests performed. In this case the average error was 0.328%. The error was calculated using the following equation. %Error= (Wind Meter Manometer)/Manometer *100 The main cause for the error was the resolution of the manometer which only had gradations in.1in intervals. This meant that the height of the oil in the tube could only be read to the nearest.05in. With 21

33 that limitation in mind, the air speed shown on the wind meter was close to the speed calculated from the manometer in all four cases. 22

34 Chapter 3 For the tests conducted in the wind tunnel, the air velocity is referred to in terms of inches of manometer oil. Below, on Table 3-1, is an approximate conversion from in Oil to m/s. For this table, the temperature and barometric pressure were assumed. In the actual tests, the values of the ambient temperature and barometric pressure were recorded for use in calculating the specific air velocity and power for that test. Table 3-1 is for reference to give an approximate idea of the air s velocity in familiar units. Table 3-1: Approximate Air Velocities in m/s Manometer Temperature Barometer Air Density Air Velocity in Oil C in Hg kg/m^3 m/s Wind Tunnel Tests with Generator A majority of the testing in the wind tunnel was performed using the generator to measure the output power. The main tests done using the generator consisted of taking multiple readings at the same air speed. This was done at a manometer reading of 0.55in to 1in in 0.05in intervals with 10 readings taken at each. The readings were then averaged for each interval. The tabulated raw data and calculated values for output power and efficiency can be found in Appendix B. 23

35 3.1.1 Results from 0.55in Oil Test 3.5 Rotational Velocity at 0.55in Oil, Generator Rotational Velocity (RPS) Rotational Velocity Average Velocity Reading Number Figure 3-1: Rotational Velocity at 0.55in Oil The results from the test taken at 0.55in Oil in the manometer can be seen in Figures 3-1, 3-2 and 3-3. The turbine rotated with a velocity around 3.36 revolutions per second (RPS), which was not a high enough rate to get a meaningful voltage out of the generator used, which the output power and efficiency results clearly show. The primary purpose of this test is that it shows that the generator needs to be turning at a minimum rate that lies between the results of this test and the test performed at 0.60in Oil. 24

36 Output Power at 0.55in Oil, Generator Output Power (W) Output Power Average Output Reading Number Figure 3-2: Output Power at 0.55in Oil Efficiency (%) Efficiency at 0.55in Oil, Generator Reading Number Efficiency Average Efficiency Figure 3-3: Efficiency at 0.55in Oil 25

37 3.1.2 Results from 0.60in Oil Test 5.3 Rotational Velocity at 0.6in Oil, Generator Rotational Velocity (RPS) Reading Number Rotational Velocity Average Velocity Figure 3-4: Rotational Velocity at 0.6in Oil The rotational velocity at 0.6in Oil, as shown in Figure 3-4, was slightly less than 2RPS faster than it was at 0.55in Oil. This rotational velocity surpassed the minimum needed to be able to get the generator to create a current. The output power, shown in Figure 3-5 was very stable, with only two points differing from the rest. As such, the efficiency, shown in Figure 3-6 was in general close to its average for the test as well. 26

38 Output Power (W) Output Power at 0.6in Oil, Generator Reading Number Output Power Average Output Figure 3-5: Output Power at 0.6in Oil 0.28 Efficiency at 0.6in Oil, Generator Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-6: Efficiency at 0.6in Oil 27

39 3.1.3 Results from 0.65in Oil Test Rotational Velocity (RPS) Rotational Velocity at 0.65in Oil, Generator Rotational Velocity Average Velocity Reading Number Figure 3-7: Rotational Velocity at 0.65in Oil The test conducted with the air velocity set at 0.65in Oil was, like the test conducted at 0.6in Oil, relatively stable in terms of rotational velocity, output power and efficiency. The variations of the rotational velocity, output power and efficiency as compared to their average over the whole test can be seen in Figures 3-7, 3-8 and 3-9 respectively. 28

40 Output Power (W) Output Power at 0.65in Oil, Generator Reading Number Output Power Average Output Figure 3-8: Output Power at 0.65in Oil Efficiency at 0.65in Oil, Generator 0.35 Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-9: Efficiency at 0.65in Oil 29

41 3.1.4 Results from 0.70in Oil Test 6.85 Rotational Velocity at 0.7in Oil, Generator Rotational Velocity (RPS) Rotational Velocity Average Velocity Reading Number Figure 3-10: Rotational Velocity at 0.7in Oil The test conducted at an air velocity of 0.7in Oil was relatively stable as well. The power measurements only showed two points that differed from the rest while the rotational velocity measurements showed the turbine maintaining a relatively consistent velocity. Figures 3-10, 3-11 and 3-12 show the results from this test, comparing the individual readings to the average values of that test. 30

42 0.73 Output Power at 0.7in Oil, Generator Output Power (W) Output Power Average Output Reading Number Figure 3-11: Output Power at 0.7in Oil 0.36 Efficiency at 0.7in Oil, Generator Effciency (%) Efficiency Average Efficiency Reading Number Figure 3-12: Efficiency at 0.7in Oil 31

43 3.1.5 Results from 0.75in Oil Test Rotational Velocity at 0.75in Oil, Generator Rotational Velocity (RPS) Reading Number Rotational Velocity Average Velocity Figure 3-13: Rotational Velocity at 0.75in Oil Unlike the previous few tests, the test at 0.75in Oil showed more variation in the results. Throughout the test, the rotational velocity varied more than in previous tests, and going from the higher end of the range down to the lower end of the range and then back up again. The output power and efficiency show similar variation during the first half of the test before leveling off during the second half. This variation shows a weakness with the timing of the readings. With the readings spaced out as they were, there was the chance that the point taken at the time of the reading was not indicative of the actual performance over all. The results from this can be seen in Figures 3-13, 3-14 and

44 0.79 Ouptut Power at 0.75in Oil, Generator 0.78 Output Power (W) Output Power Average Output Reading Number Figure 3-14: Output Power at 0.75in Oil Effciency at 0.75in Oil, Generator 0.35 Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-15: Efficiency at 0.75in Oil 33

45 3.1.6 Results from 0.80in Oil Test 7.22 Rotational Velocity at 0.8in Oil, Generator Rotational Velocity (RPS) Rotational Velocity Average Velocity Reading Number Figure 3-16: Rotational Velocity at 0.8in Oil Like the test performed at 0.8in Oil, the test at 0.85in oil showed more variation in the output power and efficiency calculations than the earlier tests, though the rotational velocity was relatively consistent. The test further illustrates the fluctuations in power output from the generator. The results of the test can be seen in Figures 3-16, 3-17 and

46 0.86 Output Power at 0.8in Oil, Generator 0.85 Output Power (W) Output Power Average Output Reading Number Figure 3-17: Output Power at 0.8in Oil 0.35 Efficiency at 0.8in Oil, Generator Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-18: Efficiency at 0.8in Oil 35

47 3.1.7 Results from 0.85in Oil Test Rotational Velocity (RPS) Rotational Velocity at 0.85in Oil, Generator Rotational Velocity Average Velocity Reading Number Figure 3-19: Rotational Velocity at 0.85in Oil The test at an air velocity of 0.85in Oil turned out to be the most consistent in terms of power output, with only one point differing from the others, right at the end of the test, as seen in Figure The rotational velocity, Figure 3-19, is like the other tests and shows some variation, due to the method the oscilloscope uses to count the pulses from the tachometer and display the frequency of them. The calculated efficiency for each reading can be seen in Figure

48 1.01 Output Power at 0.85in Oil, Generator Output Power (W) Output Power Average Output Reading Number Figure 3-20: Output Power at 0.85in Oil 0.37 Efficiency at 0.85in Oil, Generator Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-21: Efficiency at 0.85in Oil 37

49 3.1.8 Results from 0.90in Oil Test 8.32 Rotational Velocity at 0.9in Oil, Generator Rotational Velocity (RPS) Rotational Velocity Average Velocity Reading Number Figure 3-22: Rotational Velocity at 0.9in Oil The rotational velocity, as seen in Figure 3-22, for the test conducted with an air velocity at 0.9in Oil again displayed a range of values with a difference between the high and low value being around 0.16RPS. Like other tests, this can mostly be attributed to the oscilloscopes error. The power and efficiency calculations show variability during the early readings of the test and then level off for the last five readings, as shown in Figures 3-23 and The power fluctuation covers a rather significant range, considering the scale of the output. This could indicate that either the turbine or the generator with its resistor reaching a limit in their performance. 38

50 1.06 Output Power at 0.9in Oil, Generator 1.04 Output Power (W) Output Power Average Output Reading Number Figure 3-23: Output Power at 0.9in Oil 0.36 Effciency at 0.9in Oil, Generator Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-24: Efficiency at 0.9in Oil 39

51 3.1.9 Results from 0.95in Oil Test 9.05 Rotational Velocity at 0.95in Oil, Generator Rotational Velocity (RPS) Rotational Velocity Average Velocity Reading Number Figure 3-25: Rotational Velocity at 0.95in Oil At an air velocity of 0.95in, the rotational velocity, as seen in Figure 3-25, was less consistent than many of the other tests conducted with this configuration. This observation goes over to the power and efficiency results, shown in Figures 3-26 and 3-27 respectively, as well. The range that contains all of the power calculations is almost as large as the range in the previous test. 40

52 Output Power (W) Output Power at 0.95in Oil, Generator Reading Number Output Power Average Output Figure 3-26: Output Power at 0.95in Oil Efficiency at 0.95in Oil, Generator 0.35 Efficiency (%) Efficiency Average Efficiency Reading Number Figure 3-27: Efficiency at 0.95in Oil 41

53 Results from 1.0in Oil Test 9.05 Rotational Velocity at 1in Oil, Generator Rotational Velocity (RPS) Rotational Velocity Average Velocity Reading Number Figure 3-28: Rotational Velocity at 1in Oil The final test with the generator was conducted at an air velocity of 1in Oil. In Figure 3-28, it shows that the rotational velocity again has a wide range of variation, though on average is about the same as it was in the tests conducted at 0.95in Oil. The output power and efficiency, shown in Figures 3-29 and 3-30 respectively, show similar averages to the 0.95in Oil test as well, though a much smaller range of variation. 42

54 1.11 Output Power at 1in Oil, Generator Output Power (W) Output Power Average Output Reading Number Figure 3-29: Output Power at 1in Oil Efficiency (%) Efficiency at 1in Oil, Generator Reading Number Efficiency Average Efficiency Figure 3-30: Efficiency at 1in Oil 43

55 Rotational Velocity Results In general, the rotational velocity of the turbine rose as the air speed in the wind tunnel increased, though the rate of increase was not constant and reached a plateau at 0.95in Oil. Figure 3-31 shows the averaged rotational velocity from each wind velocity that the static test was conducted at. Rotational Velocity (RPS) Rotational Velocity Wind Velocity (in Oil) Rotational Velocity Figure 3-31: Rotational Velocity of the Turbine Across all Wind Velocities. At each speed however, there was some variation in rotational velocity over the course of a single test. The percent error for each reading was determined by dividing the difference of the individual reading and the average rotational velocity by the average rotational velocity. The average error ranged from an average error of 0.433% at 0.8in Oil to 1.665% at 0.55in Oil. The error curve can be seen in Figure

56 Average Percent Error (%) Rotational Velocity Error Air Velocity (in Oil) Rotational Velocity Figure 3-32: Percent Error The primary source of the error seen in the rotational velocity is rounding errors made by the oscilloscope used to read the output from the tachometer. When the oscilloscope is reading the rotational velocity, it counts the number of pulses over a certain period of time and then divides that number by the time period to give a reading in Hz. Depending on the time period used the number of pulses, even if they are occurring at a regular rate, in that period may not be the same as the number of pulses in the previous time period. In the case of the higher error at the 0.55in Oil test point the turbine was observed to have an unstable rotational velocity. If the air velocity in the wind tunnel was lower than 0.55in Oil, it was observed that the turbine s velocity would become visible more erratic as the air power to keep the turbine going in that environment was just not there. 45

57 Turbine Power Results The power readings from the generator were much more consistent, in that most readings on a given test were the same with a few outliers, than the rotational velocity readings. The output power however, was much lower than anticipated. With air power across the projected area of the turbine in excess of 300W at the highest air velocity settings, the turbine put out just more than 1W in electrical power from the generator. From initial assumptions, an output of 60W to 90W was expected at the top air velocities based on the efficiency figures claimed by Professor Gorlov. Output Power (W) Output and Air Power Air Velocity (in Oil) Air Power (W) Output Power Air Power Figure 3-33: Output Power from Generator and Air Power Figure 3-33 shows how the output power for the turbine changes as the air speed increases. As can be seen, the air power increases following the path of a third order polynomial, which is based on how the air power is calculated. It could be speculated that the output power would follow a similar path in an ideal situation; however that is not the case here. Instead the output power follows a logarithmic patch, reaching an asymptote at around 1W. The output for the first speed setting is omitted due to observation that the rotational velocity at that setting was not enough to produce a meaningful voltage from the generator. 46

58 The error with respect to the average output at each point was higher on average than the error for the rotational velocity. The highest error was at 0.55in Oil where the average error was %. This is an outlier since the generator at this air velocity was showing virtually no voltage. Outliers aside, the error ranged from 0.942% at 0.85in Oil at the low point to 3.826% at 0.9in Oil at the high point. For the tests that had lower average error, the error tended to be caused by a couple points being either higher or lower than the others while a significant majority of the points were the same. The average error over all the air velocities tested at, excluding the test at 0.55in Oil can be seen in Figure Percent Error (%) Output Power Error Air Velocity (in Oil) Output Power Error Figure 3-34: Output Power Error 47

59 Turbine Efficiency Results The turbine efficiency in these tests was poor, managing just over 0.35% at best. This is well below the expected 25% efficiency. Since the efficiency is calculated from the output power of the turbine and compare to the power of the air over the projected area of the turbine which is constant, the efficiency has the same error as the output power. Like the output power, the efficiency at 0.55in Oil is an outlier due to the fact that the generator used to measure the power was not producing a significant voltage at that velocity. Efficiency Efficiency (%) Efficiency Air Velocity (in Oil) Figure 3-35: Efficiency Figure 3-35 shows how the efficiency changes as the air velocity increases. As it can be seen, the efficiency stays around the.33% to.35% range and then drops off as the air velocity reaches 1in Oil. This follows the observations gained from the output power readings where the output power stagnated once the air velocity reached 0.95in Oil. 48

60 3.2 Wind Tunnel Tests with Torque Meter Much of the early testing of the turbine in the wind tunnel was performed with the torque meter. As the results from the generator show, the turbine performed much worse than expected. With the early results with the torque meter, it was unclear whether or not the turbine was really performing that poorly or if there was a problem with the instrumentation. It was these initial tests that spurred the use of the generator as a way to check that the torque was indeed operating correctly. The generator confirmed that the turbine was not performing as expected, though it was observed that at the same air velocities, more power was being generated when the generator was used than when the torque meter was used. On comparing rotational velocity readings, it was found that the turbine turned significantly slower when the torque meter was attached than when the generator was attached. Another issue that was observed was that for each test, the tare value for the torque meter was significantly different. The few tests that were run with the torque meter in the wind tunnel were done as ramps, where the test was started at a low air velocity and it was then ramped up at set intervals, with data taken at each point. This method was used due to the changing tare value for the torque meter. The raw data and calculated properties can be found tabulated in Appendix B 49

61 1.2 Output Power, Torque Meter vs. Generator 1 Output Power (W) Tare: Tare: Tare: Generator Air Velocity (in Oil) Figure 3-36: Output Power of Turbine using the Torque Meter and Generator Figure 3-36 shows that with the torque meter, the measured output power is only half of what was measured using the generator. Also note that the output power for the tare run with the torque meter is noticeably higher than the and tare runs. In theory the output torque measured should be roughly the same across all tests, since the tare sets the displayed value to zero before the test begins. It was observed, however, the value of the tare was dependent, in some degree to the initial position of the turbine, suggesting some imbalance either in the turbine or in the flexible coupler used to couple the shafts to one another. 50

62 10 Rotational Velocity, Torque Meter vs. Generator Rotational Velocity (RPS) Air Velocity (in Oil) Tare: Tare: Tare: Generator Figure 3-37: Rotational Velocity, Torque Meter vs. Generator Figure 3-37 shows that with the torque meter in place, the turbine rotated at a much slower rate in the wind tunnel than it did with the generator. This shows that there was significantly more resistance in the torque meter set up than there was in the generator set up. Due to this, the data gathered from the generator provides a much more accurate picture of what is going on. 3.3 Out of Wind Tunnel Test with Torque Meter For the tests conducted outside the wind tunnel, the torque meter had to be used because the turbine did not rotate at a high enough velocity to produce a measurable voltage drop across the resistor attached to the generator. Like the tests using the torque meter conducted inside the wind tunnel, the varying tare value caused some inconsistencies in the torque values read from the torque meter. However, the varying 51

63 rotational velocity given by the tachometer was the main source for the differences in the output power shown Fan 12in from Turbine The test was run four times with the fan placed 12in away from the turbine, with the torque meter being zeroed at the beginning of each test. The measured air velocity was relatively consistent, ranging from 5m/s to 5.3m/s. Torque with Fan 12in from Turbine Torque (Nm) Reading Number Tare: Air: 5.2m/s Tare: Air: 5.3m/s Tare: Air: 5.2m/s Tare: Air: 5m/s Figure 3-38: Torque from Tests Taken with Fan 12in from Turbine Figure 3-38 shows how the torque varied with each test. The main correlation that can be derived is that the torque values are dependent on the tare value of the torque meter at the time that the test was performed. The reason the tare value has such a noticeable effect on the outcomes of these tests is due to the extremely low output torques seen from this turbine. If the turbine was performing as expected, the differences caused by the change in the tare would be a small percentage of the overall measured torque. 52

64 0.7 Rotational Velocity with Fan 12in from Turbine Rotational Velocity (RPS) Reading Number Tare: Air: 5.2m/s Tare: Air: 5.3m/s Tare: Air: 5.2m/s Tare: Air: 5m/s Figure 3-39: Rotational Velocity Taken from Tests with Fan 12in from Turbine Above in Figure 3-39, the rotational velocities measured in the tests can be seen. The rotational velocities remained rather consistent across the tests which is expected, since the fan only had one speed setting and remained in the same position for all four of the tests run. 53

65 0.03 Output Power with Fan 12in from Turbine Output Power (W) Reading Number Tare: Air: 5.2m/s Tare: Air: 5.3m/s Tare: Air:5.2m/s Tare: Air: 5m/s Figure 3-40: Output Power Calculated from Tests Taken with Fan 12in from Turbine Efficiency (%) Efficiency with Fan 12in from Turbine Tare: Air: 5.2m/s Tare: Air: 5.3m/s Tare: Air: 5.2m/s Tare: Air: 5m/s Reading Number Figure 3-41: Efficiency Calculated from Tests Taken with Fan 12in from Turbine 54

66 The output power of the turbine in these tests can be seen in Figure 3-40 and the efficiency in Figure Both calculated properties follow the same curves as they are directly related to one another. However, the output power results appear closer to each other since they do not take into account the different measured air velocities. In theory, the measured air velocity should have been the same for each test. In practice, getting the wind meter in the same exact position for every test proved impossible. Since the reading taken from the meter was dependent on its position for each test when the air velocity reading was taken, the measured values differ somewhat Fan 24in from Turbine. The second set of tests performed with the turbine outside the wind tunnel were done with the fan positioned 24in from the turbine. The air velocity during these tests was only slightly lower than it was with the fan 12in from the turbine with the velocity for these tests ranging from 4.9m/s to 5.1m/s Torque with Fan 24in from Turbine Torque (Nm) Tare: Air: 5.1m/s Tare: Air: 5m/s Tare: Air: 5.1m/s Tare: Air: 4.9m/s Reading Number Figure 3-42: Torque Taken from Tests with Fan 24in from Turbine 55

67 Figure 3-42 shows the torque measured from each test across all ten readings for each. As the figure shows, the torque for all four tests remained relatively stable for the duration of each test and like the previous tests done at 12in varied from test to test based on the tare value. Rotational Velocity (RPS) Rotational Velocity with Fan 24in from Turbine Tare: Air: 5.1m/s Tare: Air: 5m/s Tare: Air: 5.1m/s Tare: Air: 4.9m/s Reading Number Figure 3-43: Rotational Velocity from Tests Taken with Fan 24in from Turbine The rotational velocity, shown in Figure 3-43 is not as consistent across the four tests at 24in as it was across the four tests at 12in. Both the output power and efficiency, shown in Figures 3-44 and 3-45, show a much larger spread than the tests at 12in. This is mainly a result of the less consistent rotational velocities measured during these tests. 56

68 0.025 Output Power with Fan 24in from Turbine Output Power (W) Tare: Air: 5.1m/s Tare: Air: 5m/s Tare: Air: 5.1m/s Tare: Air: 4.9m/s Reading Number Figure 3-44: Output Power Calculated from Tests Taken with Fan 24in from Turbine Efficiency (%) Efficiency with Fan 24in from Turbine Tare: Air: 5.1m/s Tare: Air: 5m/s Tare: Air: 5.1m/s Tare: Air: 4.9m/s Reading Number Figure 3-45: Efficiency Calculated from Tests Taken with Fan 24in from Turbine 57

69 3.4 Conclusions Overall, the turbine did not perform anywhere near what was expected at the outset of this investigation. Results of 25% to 30% efficient would have fallen right in line with the claims made about the efficiency of this design and results of around 20% efficient would have shown promise. Instead, the tests conducted throughout this investigation, using multiple measurement techniques both in and out of the controlled environment of the wind tunnel, returned results equal to roughly one hundredth of what was anticipated. The selection of the instrumentation used for the investigation was based on the claims laid out for the helical turbine. When the initial results showed such low numbers, they called into question the accuracy of the equipment being used, most prominently the torque meter. As the results show, the generator backed up the results from the torque meter. A primary observation with the torque meter was that at the range of torque that the turbine was producing, the tare value which zeroed the torque meter at the beginning of the test had a significant effect on the torque read. This has to do mainly with the output torque being so small compared to the designed range of the torque meter. The torque meter was selected based on the assumptions made based on claims made about the devise. A performance so far below what was expected was not anticipated during the selection process for the instrumentation. While studies have been made with this design as a hydro-turbine and returned some promising results, the same can not be said for this design s performance as an air turbine. The tests performed in this investigation suggests that this design in impractical as an air turbine. 58

70 It is unclear what caused the far lower than expected results from this investigation. It is well known that turbines with blades that are transverse to their axis of rotation can be efficient enough to be used commercially (9), even though they do not necessarily use a helical design. Dr. Gorlov himself claims his design is more efficient than those of the Darrius type. A company in England even produces a wind turbine that is very similar to the designs specified by Dr. Gorlov (10). Given this evidence, it can be concluded that the results of this investigation were not typical and more must be done through further investigations to isolate what caused the poor performance of this investigation. 3.5 Further Investigations While the results from this investigation were not what were expected, there is still plenty of room for further investigation. Possible investigations that can still be made are as follows. 1) Experiment with different angles of attack where the angle of attack is defined as the angle between the chord line of the air foil and the tangent line of the point where the midpoint of the chord line intersects the arc of the turbine. All the tests performed in this investigation were conducted with blades set at a 0 degree angle of attack. An investigation to determine whether or not varying the angle of attack has any effect on the performance of this design could still be conducted. 2) Another idea would be to model the turbine in Fluent or another computational program and see if the results from that confirm the results this study showed using both a torque meter and a generator. 59

71 3) Use a larger turbine in open air with a more powerful fan driving it. A larger turbine will result in a larger, easier to measure output. 4) Test the turbine in wind tunnel with a larger test section to reduce the effects that the walls of the wind tunnel might have, but maintain the controlled environment. These are only some ideas of what can still be done. While this study suggests that the helical turbine based on the design proposed by Dr. Gorlov is not practical as an air turbine, it is also not enough to prove it either. Further tests and investigations should be performed. 60

72 Works Cited 1. Darrius, Georges Jean Marie. Turbine Having its Rotating Shaft Transverse to the Flow of the Current. 1,835,018 United States of America, December 8, Gorban, Alexander N., Gorlov, Alexander M. and Silantyev, Valentin M. Limits of the Turbine Efficiency for Free Fluid Flow. s.l. : ASME, December 2001, Journal of Energy Resources Technology, Vol. 123, pp Marburg, Gustav. Submerged Water Wheel. 707,857 United States of America, April 21, Gorlov, Alexander M. Unidirectional Helical Reaction Turbine Operable Under Reversible Fluid Flow for Power Systems. 5,451,137 United States of America, September 19, Gorlov, Alexander M. Helical Turbine Assembly Operable under Multidirectional Gas and Water Flow for Power and Propulsion Systems. 6,155,892 United States of America, December 5, Gorlov, Alexander M. The Helical Turbine: A New Idea for Low-Head Hydro. September 1995, Hydro Review, pp Howell, Robert, et al., et al. Wind Tunnel and Numerical Study of a Small Veritcal Axis Wind Turbine. s.l. : Elsevier, 2010, Renewable Energy, Vol. 35, pp Wilks, Neil. Wind City. Environmental Engineering. March 2009, pp Peace, Steven. Another Approach to Wind. Mechanical Engineering. June 2004, pp Quiet Revolution. [Online] [Cited: August 4, 2011.] 61

73 Appendix A: Technical Drawings of Turbine Figure A-1: Dimensioned Drawing for Turbine Shaft 62

74 Figure A-2: Dimensioned Drawing of the Flanged Shaft Mount for the Turbine 63

75 Figure A-3: Dimensioned Drawing of the Spoked Arm Wheel for the Turbine ` 64

76 Figure A-4: Dimensioned Drawing of the Top Half of the Turbine Blade 65

77 Figure A-5: Dimensioned Drawing of Bottom Half of the Turbine Blade 66

78 Appendix B: Raw Data Table B-1: In Wind Tunnel with Generator, 0.55in Oil Temperature 24.5 Width of Turbine (in) 10 Air Speed (in Oil) 0.55 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power # RPS *3 V RPS W Efficiency Rotational Velocity Error Output Power Error Efficiency Error Average:

79 Table B-2: In Wind Tunnel with Generator, 0.6in Oil Temperature 24 Width of Turbine (in) 10 Air Speed (in Oil) 0.6 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power # RPS *3 V RPS W Efficiency Rotational Velocity Error Output Power Error Efficiency Error Average:

80 Table B-3: In Wind Tunnel with Generator, 0.65in Oil Temperature 23.5 Width of Turbine (in) 10 Air Speed (in Oil) 0.65 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power # RPS *3 V RPS W Efficiency Rotational Velocity Error Output Power Error Efficiency Error Average:

81 Table B-4: In Wind Tunnel with Generator, 0.7in Oil Temperature 23 Width of Turbine (in) 10 Air Speed (in Oil) 0.7 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

82 Table B-5: In Wind Tunnel with Generator, 0.75in Oil Temperature 22 Width of Turbine (in) 10 Air Speed (in Oil) 0.75 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

83 Table B-6: In Wind Tunnel with Generator at 0.8in Oil Temperature 21 Width of Turbine (in) 10 Air Speed (in Oil) 0.8 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

84 Table B-7: In Wind Tunnel with Generator at 0.85in Oil Temperature 22 Width of Turbine (in) 10 Air Speed (in Oil) 0.85 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Speed Voltage Rotational Velocity Output Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

85 Table B-8: In Wind Tunnel with Generator at 0.9in Oil Temperature 22 Width of Turbine (in) 10 Air Speed (in Oil) 0.9 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Raw Rotational Rotational Output Reading Speed Voltage Velocity Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

86 Table B-9: In Wind Tunnel with Generator at 0.95in Oil Temperature 22.5 Width of Turbine (in) 10 Air Speed (in Oil) 0.95 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Raw Rotational Rotational Output Reading Velocity Voltage Velocity Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

87 Table B-10: In Wind Tunnel with Generator at 1in Oil Temperature 22.5 Width of Turbine (in) 10 Air Speed (in Oil) 1 Width of Turbine (m) Barometric Pressure (in Hg) Length of Turbine (in) 14 Resistor (ohms) 10 Length of Turbine (m) Specific Gravity of Oil Area of Turbine (m^2) Air Speed (m/s) Air Density (kg/m^3) Air Power (W) Reading Raw Rotational Velocity Voltage Rotational Velocity Output Power Efficiency # RPS *3 V RPS W Rotational Velocity Error Output Power Error Efficiency Error Average:

88 Table B-11: In Wind Tunnel with Generator Averages Wind Rotational Output Air Manometer Velocity Efficiency Velocity Power Power in Oil m/s RPS W W Rotational Velocity Error Output Power Error Efficiency Error Table B-12: In Wind Tunnel with Torque Meter, Test 1 Temperature 26 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Resistor (g) 50 Length of Turbine (in) 14 Specific Gravity of Oil Length of Turbine (m) Air Density (kg/m^3) Area of Turbine (m^2) Tare Raw Rotational Rotational Output Reading Manometer Velocity Torque Velocity Power Air Velocity Air Power Efficiency # in Oil RPS *3 Nm RPS W m/s W

89 Table B-13: In Wind Tunnel with Torque Meter, Test 2 Temperature 26 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Resistor (g) 50 Length of Turbine (in) 14 Specific Gravity of Oil Length of Turbine (m) Air Density (kg/m^3) Area of Turbine (m^2) Tare Reading Manometer Raw Rotational Velocity Torque Rotational Velocity Output Power Air Velocity Air Power Efficiency # in Oil RPS *3 Nm RPS W m/s W

90 Table B-14: In Wind Tunnel with Torque Meter, Test 3 Temperature 26 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Resistor (g) 50 Length of Turbine (in) 14 Specific Gravity of Oil Length of Turbine (m) Air Density (kg/m^3) Area of Turbine (m^2) Tare Raw Rotational Rotational Output Air Reading Manometer Velocity Torque Velocity Power Air Velocity Power Efficiency # (in oil) RPS *3 Nm RPS W m/s W

91 Table B-15: Out of Wind Tunnel with Torque Meter at 12in, Test 1 Temperature 25 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Torque Air Reading Distance Velocity Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

92 Table B-16: Out of Wind Tunnel with Torque Meter at 12in, Test 2 Temperature 25 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Torque Air Reading Distance Velocity Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

93 Table B-17: Out of Wind Tunnel with Torque Meter at 12in, Test 3 Temperature 26 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Air Reading Distance Velocity Torque Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

94 Table B-18: Out of Wind Tunnel with Torque Meter at 12in, Test 4 Temperature 26 Width of Turbine (in) 10 Barometric Pressure (in Hg) 29.9 Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Air Reading Distance Velocity Torque Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

95 Table B-19: Out of Wind Tunnel with Torque Meter at 24in, Test 1 Temperature 25 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Torque Air Reading Distance Velocity Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

96 Table B-20: Out of Wind Tunnel with Torque Meter at 24in, Test 2 Temperature 25 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Torque Air Reading Distance Velocity Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

97 Table B-21: Out of Wind Tunnel with Torque Meter at 24in, Test 3 Temperature 25 Width of Turbine (in) 10 Barometric Pressure (in Hg) 29.9 Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) Raw Rotational Velocity Torque Air Reading Distance Velocity Rotational Velocity Output Power # in m/s RPS *3 Nm RPS W W Air Power Efficiency

98 Table B-22: Out of Wind Tunnel with Torque Meter at 24in, Test 4 Temperature 25 Width of Turbine (in) 10 Barometric Pressure (in Hg) Width of Turbine (m) Air Density (kg/m^3) Length of Turbine (in) 14 Tare Length of Turbine (m) Area of Turbine (m^2) 2 Raw Rotational Velocity Distanc Air Rotational Output Reading e Velocity Torque Velocity Power # in m/s RPS *3 Nm RPS W W Air Power Efficienc y

99 Appendix C: Calibration Information Figure C-1: Torque Meter Calibration Sheet 88

100 Figure C-2: Torque Meter Spec Sheet 89

101 Figure C-3: Tachometer Spec Sheet Side 1 90

102 Figure C-4: Tachometer Spec Sheet Side 2 91