QUALITY OF VORTEX FORMED USING VORTEX FLOW CHANNEL

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 5, May 2017, pp , Article ID: IJMET_08_05_056 Available online at aeme.com/ijmet/issues.asp?jtype=ijmet&vtyp pe=8&itype=5 ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EFFECT OF INLET GEOMETRY IN THE QUALITY OF VORTEX FORMED USING VORTEX FLOW CHANNEL Dipesh Thapa and Aakash Mishra IV/IV B Tech. Mechanical Engineering, KL University, India. K. Sai Sarath Assistant Professor, Mechanical Engineering, KL University, India. ABSTRACT The major objective of present work is to study effect of the inlet geometry in the quality of water vortex produced by the vortex flow channel. The experimentation is done using ANSYS FLUENT. Vortex flow channel is the channel in which the low Reynolds turbulent (or laminar) flow is converted to high Reynolds turbulent (or turbulence) flow by producing the swirl or vortex pattern. The Vortex flow channel is basically used to produce the hydroelectricity using low head water. The project is based upon the idea thatt the symmetric behavior of the pressure along the radial distance of the vortex will result in the low thrust force in the turbine which finally enhances the overall efficiency. In the project the vortex flow channel of various inlet geometry like triangular, rectangular, circular and curved are used and the pressure and kinetic energy variation along the radial distance within thesee different inlet geometry is compared. From the experiment it has been found that the flow channel with rectangular and circular inlet tends to produce more symmetric pressure variation in comparisons to triangular and curved geometry.. Key words: Vortex flow channel, Quality of vortex, Vortex turbine, Vortex Flow. Cite this Article: Dipesh Thapa, Aakash Mishra and K. Sai sarath Effect of Inlet Geometry in the Quality of Vortex Formed Using Vortex Flow Channel. International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp IType=5 1. INTRODUCTION Many of the researchers have shown that about 16% (3427 terawatt-hours) of global electricity generation are contributed by hydroelectricity. Hydroelectricity is one of the major sources of green energy and is generated through the use of gravitational force of falling or flowing water. The flow with high pressure head and kinetic energy are generally capable of producing more economical hydroelectricity which make a use of radial or axial flow turbine but Now a days the electricity are also effectively generated with the low pressure head flow editor@iaeme.com

2 Dipesh Thapa, Aakash Mishra and K. Sai Sarath of the range 0.7 to 3 meter, which is achieved by converting the linear flow water into vortex flow by using vortex flow channels. Vortex turbine have about 80% of theoretical efficiency but 73% has been reported so far. There are numerous reasons like quality of vortex, frictional losses and turbine geometry responsible for these losses in efficiency. Among the above mentioned losses, frictional losses plays important role in linear flow hydro power plant whereas the quality of the vortex plays important role in vortex flow hydro power plant. Generally the symmetricity of the pressure along the radial distance is assumed to be important parameter to assist the quality vortex in the view of electricity generation. The vortex turbine is a low pressure turbine which works with apressrehead as low as 0.7 m, with a performance similar to that of the traditional hydro turbines that used in the production of renewable energy with simbiotic environmental effect (Zotlöterer, 2014) [1]. The water travels through a huge and long entrance over the channel, then clears tangentially to the circular chamber, that produces a tremendous cyclon. The outlet is made at the bottom of the circular chambervia which the waterleaves the channel (Mulligan & Hull, 2010)[2]. The vortex turbine works on the principle of dynamic force due to vortex rather than the principle of differential pressure. This goal is achieved by using hydroelectric power station which forms the stable gravitational vortex by using the specially designed channels without using the pressure line directing devices. These channels can also be made multipurpose, for example same channel can be made as ariater of water and also for the production of green and eco friendly electricity. The vortex turbine that rotates in the vortex channel. whenever these turbine strikes the rotating water throughout the circumference converts the rotational kinetic energy of the vortex into the green electrical energy in a generator (Zotlöterer, 2014)[1] Figure 1 Vortex formation in vortex flow channel 2. COMPUTATIONAL FLUID DYNAMICS Computational Fluid dynamics is defined as the branch of science that uses computer resources to simulate flow-related problems. CFD software makes uses of established mathematical relations, to simulate a flow problem and analyze it. CFD software solves large number of mathematical equations by using matrix based solver to reach the result. All of the CFD software that are known uses simplified user interface that allows user to simulate the probelm using simple codes, drag and drop menu and predefined steps. All CFD procedure involes three major steps: (i) a pre-processor, (ii) a solver, and (iii) a postprocessor. These steps must be followed without escaping to reach the result. The brief introduction of these steps have been discussed below editor@iaeme.com

3 Effect of Inlet Geometry in the Quality of Vortex Formed Using Vortex Flow Channel 2.1. Pre-Processor Pre-processing involves in taking of a flow problems from a user by using a user friendly operator interface and then transforms the same input a form which is suitable for using the solver. User activity during pre-processing are as follow: Defining the geometrical properties, region, domain. Grid generation: deviding the domain into several small disjoint subdomains: a grid (or mesh) of cells ( or control elements). Physical and chemical occurences to be modeled will be selected. Determining the properties of fluids. Specifying the suitable boundary conditions in cells that match or sense the boundary of the domain Solver There are three different ways recognized for numerical solution: finite differences, finite elements and spectral methods. On the diagram of numerical methods that form the basis of solver to perform the following steps: Approach a flow of unknown variables using simple functions. Mathematical manipulations and Discretization of governing flow eqution by substituting approximation. Solving the algebric equation. The major differences that lies between the three streams are the approach they made for discritization process and flow variables. Here the finite volume method have been used Post-Processor There has been a lot of development work taken place recently in post processing field. Because of growing popularity of engineering workstations, out of which many are having high graphic capabilities, the CFD packages are being furnished with versatile data visualization tools. These include: Domain geometry and grid view vector plots Surface plots Particle tracking, etc. 3. LITERATURE REVIEW The concept of producing electricity using vortex flow was first invented by Austrian engineer Franz Zotlöterer [1] while attempting to find a way to aerate water without an external power source. He was able to produce 8.3 kw of power using the water of flow rate 0.9m3/s and the head of 1.8m. Zotlöterer[1] also comitted the water vortex power plant is completely safe for aquatic animal. Tze Cheng Kueh et al. [3] performed the numerical analysis for the water vortex formation for the water vortex plant. They found that as the hole of the outlet is getting increased the more turbulent the flow has become which makes the CFD modling more complex. However, the this complexity can be improved by choosing better turbulent modela.subash Dhakal et al [4] published the journal on Development and Testing of Runner and Conical Basin for the Gravity Water Vortex power Plant. In his editor@iaeme.com

4 Dipesh Thapa, Aakash Mishra and K. Sai Sarath journal he mentioned that the efficiency values were higher for turbines with fewer blades. Ooi. Y. et al [5] performed the numerical analysis of water vortex for electricity generation. R. K. Choulaghai [6] made an attempt to devlope the vortex turbine.dipesh Thapa [7] in his paper Enhancement of heat transfer using vortex flowchannels also found the significance of vortex channel in enhancing the rate of heat transfer. 4. NUMERICAL MODEL In almost all previous investigations, the air-core vortex was considered based on the assumption of constant, axisymmetric and incompressible flow. The continuity equation and the Navier-Stokes equations in cylindrical coordinates are described as follows: = 0 (1) Vr Vz - = V ( - ) (2) Vz - = V ( - ) (3) Vr Vr = g V ( ) (4) Where, Vθ, Vr and Vz are components velocity in tangential, radial and axial direction respectively, ρ detnotes fluid density, g denotes acceleration due to gravity and ν denotes kinematic viscosity. Due to the complexity of the equations, it is very difficult to solve these equations analytically to reach the solution. So, Computational Fluid Dynamics (CFD) has become cost effective for predicting the performance of Fluid flow and also the behaviour of fluid flow across a region of interest. In the present study, the simulation was performed for the visualization of the flow in the channel and to determine the distribution of the velocity through out the channel. For Simulating the result the can modeling was done using solid works and the modeled geometry was improted to ANSYS software to perform the simulation. 5. EXPERIMENTATION The experimentation was done using practical approach and virtual approach. For virtual analysis ANSYS Fluent was used. In the experiment the various in let path geometry like triangular, rectangular, circular and curved was taken. The working fluid used for all different geometry was pure water at 27 0 C and viscosity of kg/m-s. The velocity of entering water was 1.5 m/s which is also same for all different geometry. Figure 2 Experimentation of vortex turbine editor@iaeme.com

5 Effect of Inlet Geometry in the Quality of Vortex Formed Using Vortex Flow Channel 6. RESULT Figure 3 Vortex formation Figure 4 Vortex Flow channel with circular c/s geometry Figure 5 Vortex Flow channel with curved inlet geometry Figure 6 Vortex Flow channel with rectangular inlet geometry editor@iaeme.com

6 Dipesh Thapa, Aakash Mishra and K. Sai Sarath Figure 7 Vortex Flow channel with angular inlet geometry Figure 7(a) Pressure Vs. Linear distance for Vortex channel with triangular inlet geometry Figure 7(b) Turbulence K.E Vs. Linear distance for Vortex channel with triangular inlet geometry In the above Pressure vs. x- distance graph for vortex channel with triangular inlet geometry the pressure distribution of core is very symmetric about the core axis. This indicates that if we use the vortex turbine in the channel having the triangular type of inlet geometry the turbine will experience very less force along radial direction. The radial direction forces are editor@iaeme.com

7 Effect of Inlet Geometry in the Quality of Vortex Formed Using Vortex Flow Channel responsible force for creating bending moment in the turbine shaft reducing the efficiency and durability of turbine Figure 8(a) Pressure Vs. Linear distance for Vortex channel with Circular c/s inlet Figure 8(b) Turbulence K.E Vs. Linear distance for Vortex channel with circular c/s inlet In the above Pressure vs. x- distance graph for vortex channel with circular cross-section inlet geometry the pressure distribution is shiftes to positive x-direction. This indicates that if we use the vortex turbine in the channel having this type of inlet geometry the turbine will experience very high force along radial direction from left to right. The radial direction forces present here are responsible force for creating anti-clockwise bending moment in the turbine shaft reducing the efficiency and durability of turbine

8 Dipesh Thapa, Aakash Mishra and K. Sai Sarath Figure 9(a) Pressure Vs. Linear distance for Vortex channel with curved inlet geometry Figure 9(b) Turbulence K.E Vs. Linear distance for Vortex channel with curved inlet geometry In the above Pressure vs. x- distance graph for vortex channel with curved inlet geometry path the pressure distribution is quite symmetric about the core axis but is sudden high pressure region in slight right side. This sudden high pressure region is due to backflow of the fluid due to sudden contraction of inlet. This indicates that if we use the vortex turbine in the channel having this type of inlet geometry the turbine will experience very high force along radial direction from right to left. The radial direction forces present here are responsible force for creating clockwise bending moment in the turbine shaft reducing the efficiency and durability of turbine

9 Effect of Inlet Geometry in the Quality of Vortex Formed Using Vortex Flow Channel Figure 10(a) Pressure Vs. Linear distance for Vortex channel with rectangular inlet geometry Figure 10(b) Turbulence K.E Vs. Linear distance for Vortex channel with rectangular inlet geometry In the above Pressure vs. x- distance graph for vortex channel with rectangular inlet geometry path the average pressure distribution is quite symmetric about the core axis but is imbalanced high pressure region are scattered in both right and left side.. This indicates that if we use the vortex turbine in the channel having this type of inlet geometry the turbine will experience very less force along radial direction from in any direction. The radial direction forces present here are likely to create bending moment in the turbine shaft in either the direction. This means the failure of the shaft become much unexpected if the force becomes high in particular direction. Hence this type of inlet geometry path is good for low head only. 7. CONCLUSION This study is an attempt to present the effect of different inlet geometries of flow channel in the quality of vortex produced under steady state flow condition. The study shows that the vortex channel having triangular inlet geometry path are very efficient for the vortex flow hydroelectric power plant because these geometry tends to produce very symmetric vortex pattern which causes very less imbalance radial force that are responsible for the bending for turbine shaft. And the study also shows that vortex flow channel with rectangular inlet geometry path produce average pressure distribution quite symmetric but along with they also produce the random high pressure in both counter direction, which implies that the

10 Dipesh Thapa, Aakash Mishra and K. Sai Sarath rectangular inlet geometry may be effective at low head but may have unexpected failure in higher head. 8. ACKNOWLEDGEMENTS Authors were very thankful to their colleagues for providing their expertise that greatly aided the research. Authors also expressed their appreciation to Mr. J. Naveen for sharing his pearls of wisdom with them during the course of research. They were also immensely thankful to Dr. S.S. Rao for his comments and suggestion during the research. Authors are also thankful to their parents for constant help and support. REFERENCES [1] Zotloterer. (2013). Retrieved December 2012, from Zotloterer website: [2] Mulligan, S. &. (2010). The Hydraulic Design and Optimisation of a Free Water Vortex for the Purpose of Power Extraction. Sligo, Ireland: The Institute of Technology, Sligo. [3] Chen, Y., Wu, C., WANG, B., & Du, M. (2012). Three- dimensional Numerical Simulation of Vertical Vortex at Hydraulic Intake. Sichuan: Elsevier. [4] Bajracharya, T. R., Thapa, A. B., Pun, P., Dhakal, S., & Nakarmi, S. (2013). Development and testing of runner and conical basin for gravitational water vortex power plant. Institute of Engineering, Pulchowk. [5] D. & Ooi. Y. (2014). Numerical Analysis of Water Vortex Formation for the Water Vortex Power Plant. International Journal of Innovation, Management and Technology, 5, [6] Chaulagain, R. K. (2012). Development and Testing of Gravitational Water Vortex Turbine. Institute of Engineering,Pulchowk. [7] Ashvini Chavan, Dr. Bhagyesh Deshmukh and Prabhakar Pawar, A Review of Various Gear Geometry Modification Methodologies, International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp [8] J.S.Uday Kumar, Dr. CLVRSV Prasad and K.Santa Rao, Simulation Studies of Impact of Electrode Geometry on Thermal Profiles In Micro EDM by Using CFX Tools. International Journal of Mechanical Engineering and Technology, 7(4), 2016, pp [9] A. Parshuramulu, K. Buschaiah and P. Laxminarayana, A Study On Influence of Polarity on The Machining Characteristics of Sinker EDM. International Journal of Mechanical Engineering and Technology, 4(3), 2013, pp [10] Dipesh Thapa (2015), Enhancement of Heat transfer using vortex flow channel. Indian streams research journal. Vol: 5, Issue 9, Oct 2015, ISSN NO: editor@iaeme.com