Theoretical Analysis of Horizontal Axis Wind Turbine for Low Wind Velocity

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1 Available online at International Journal of Innovative and Emerging Research in Engineering e-issn: p-issn: Theoretical Analysis of Horizontal Axis Wind Turbine for Low Wind Velocity Shailesh P. Patankar1 a, Samir J. Deshmukh2 b, Rucha R. Kolhekar3 c a Student of Thermal Engineering 1,Department of Mechanical Engineering, Prof. Ram Meghe Institute Of Technology and Research, Badnera, Amravati, Maharashtra, India. b Associate Professor 2, Department of Mechanical Engineering, Prof. Ram Meghe Institute Of Technology and Research, Badnera, Amravati, Maharashtra, India. c Assistant Professor 3, Department of Mechanical Engineering, Prof. Ram Meghe Institute Of Technology and Research, Badnera, Amravati, Maharashtra, India. ABSTRACT: Wind energy is most of the promising renewable energy source. In general, Moderate to high-speed winds, typically from 5m/s to about 25m/s are considered favorable for most wind turbines in India. But in rural areas, wind speed is near about 3m/s to 6m/s. So, this wind turbine is applicable for low wind velocity. In wind turbine technology, the turbine blades play an important role as it directly comes in contact with the wind. The objective of this paper is to design the wind turbine blade and to study the various design parameters affecting design of wind turbine. This design is used to develope small wind turbine used for low power generation of 100kW at low wind speed of 3m/s to 6m/s. The design of wind turbine blade is done in CAD Software as CREO 2.0. By Velocity triangle of single blade of wind turbine, velocity can be determined and this can be implemented in design procedure to design wind turbine blade. By using the fixed blade mechanism, on an average, 45% velocity rise can be obtained at the entry to the wind turbine blade. Keywords: wind speed, fixed blade, angle of incidence, wind turbine blade. I. INTRODUCTION Wind energy is most of the promising renewable energy source. The wind energy is firstly used to produce mechanical energy and the system used to change the kinetic energy of the wind into mechanical energy is called windmill. The term wind turbine is the updated version of the term windmill. Wind turbine refers to the system which converts the wind energy into electrical energy. Wind has considerable amount of kinetic energy when blowing at high speeds. This kinetic energy when passing through the blades of the wind turbines is converted into mechanical energy and rotates the wind blades and the connected generator, thereby producing electricity [6]. In general, Moderate to high-speed winds, typically from 5m/s to about 25m/s are considered favourable for most wind turbines in India. But in rural areas, wind speed is near about 3m/s to 6m/s. So, this wind turbine is applicable for low wind velocity. With highly efficient, solid and reliable wind turbine, wind power offers a solution to meet energy needs and environmental care. The blade is key element of micro wind turbines which converts the kinetic energy of the wind and in electricity through generators [5]. Wind power represents one of the most promising sources of renewable energy: currently wind is more economically feasible than solar or biomass for electricity generation [2]. Wind turbine system that consists of a diffuser shroud with a broad-ring brim at the exit periphery and a wind turbine inside it. for a given turbine diameter and wind speed. This is because a low-pressure region, due to a strong vortex formation behind the broad brim, draws more mass flow to the wind turbine inside the diffuser shroud. Significant increase in the output power of a micro-scale wind turbine was obtained [4]. Aerodynamic shape optimization is one of the main research fields which is directly related to power production of a wind turbine [1]. In micro wind turbine, diffuser is used to create pressure drop after rotation of blades so high velocity output can be obtained [7]. In wind turbine, fixed airfoil shaped blades are mounted on fixed shaft as stator and moving blades are mounted on moving shaft. So, air impinged on fixed blades so moving blades are rotating. So, pressure reduction occurs in the 93

2 diffuser and due to pressure drop air is sucked just like a exhaust nozzle of gas turbine and velocity of wind turbine is increasing by increasing power output of system. II. AIRFOIL THEORY An Airfoil is a streamlined body bounded principally by two flattened curves and whose length and width are very large in comparison with the thickness. It has a thick, rounded leading edge and thin trailing edge. Its maximum thickness occurs somewhere near the midpoint of the chord. The backbone line lying midway between the upper and lower surfaces is camber line.[2] An airfoil means two dimensional cross section shape of wing whose purpose is to either generate lift or minimizing drag when exposed to wind.[4] When such blade is suitably shaped and properly oriented in the flow, force acting on it normal to direction of flow is considerably larger than force resisting its motion. Figure 1. Basic Wind Turbine Blade Structure Lift on body is force on body in a direction normal to flow direction. Drag on body is force on body in direction parallel to flow direction. For operating efficient jet wind turbine, lift force should be high and drag force should be low. [3] Figure 2. Forces on Fixed Blade Airfoil Aerodynamic lift is the force responsible for the power yield generated by the turbine and it is therefore essential to maximize this force using appropriate design. A resistant drag force which opposes the motion of the blade is also generated by friction which must be minimized.[6] Lift To Drag Ratio = Coefficient of Lift/Coefficient of Drag= Where, III. METHODOLOGY OF DESIGN OF WIND TURBINE BLADE Two primary parts of wind turbine are as A. Analytical Method i) Stator Nozzle ii) Rotor Blades 94

3 Most of turbines possess more than one stage which consists of ring of fixed nozzle blades followed by rotor blade ring mounted on common shaft. Energy transformation occurs in both fixed as well as moving blades. Rotor experiences both energy transfer as well as energy transformation. Figure shows a single stage turbine along with pressure and velocity changes when wind passes through a turbine stage. Figure 3. Turbine stage along with pressure and velocity change The flow geometry at entry and exit of a turbo machine stage is described by the velocity triangles which consist of following three components as i) the peripheral velocity (u) of rotor blades, ii) the absolute velocity (c) of fluid, and iii) the relative velocity (w) of fluid The notation used here to draw velocity triangles corresponding to the x-y coordinate; the suffix (a) identifies components in axial direction and the suffix (t) refers to tangential direction. Air angles in the absolute system are denoted by alpha (α), where as those in the relative system are represented by beta (β). The velocity triangles at entry and exit of wind turbine are shown in fig. 4. Since stage is axial, change in mean diameter between its entry and exit can be neglected so, peripheral or tangential velocity (u) remains constant. Figure. 4. Velocity triangles for a wind turbine 95

4 It is often assumed that the axial velocity component remains constant through the stage. For such a conditions So, By Inlet velocity and inlet blade angle α 1 other parameters can be calculated. B. Graphical Method By calculating various parameters like inlet and outlet angles of fixed and rotor blades design the fixed as well as rotor blades in CAD Software as CREO 1.0 as Figure 5. Sectional view of fixed and rotor blade Then by inlet casing, outer casing and diffuser design complete assembly of wind turbine can be completed. 96

5 Figure 6. Sectional assembly view of complete showing fixed and rotor blade, inlet casing, outer casing and diffuser So, complete assembly of wind turbine can be Figure 7. Complete assembly of jet wind turbine TABLE 1 theoretically calculated wind speed SR NO. Inlet velocity in m/s Outlet velocity in m/s Percentage increase in velocity in % 01 3 m/s 5.27 m/s 43.07% 02 4 m/s m/s 43.31% 03 6 m/s 8.63 m/s 45.37% 04 8 m/s m/s 47.63% m/s m/s 49.25% m/s m/s 51.36% From table we observed that theoretically wind speed by using jet wind turbine can be increased 2-5% than conventional wind turbine. 97

6 IV. MATERIAL SELECTION The present work demonstrates that PVC blades profile gives better power capacity with respect to increase in rotational speed of rotor.[5]. So, PVC type material can be used to manufacture the prototype of jet wind turbine. V. CONCLUSIONS From design of wind turbine, due to arranging of fixed blade before moving blades velocity of wind at outlet may be increased. Due to pressure reduction occurs in the diffuser and due to pressure drop air is sucked just like an exhaust nozzle of gas turbine and velocity of wind turbine is increasing by increasing power output of system. By using this type of wind turbine 2-5% velocity can be increased other than conventional wind turbine. By numerically, maximum wind velocity can be 10.43m/s which is 47.63% increase in velocity output. REFERENCES [1] Sandip. A. Kale and Ravindra N. Varma, Aerodynamic Design of a Horizontal Axis Micro Wind Turbine Blade Using NACA 4412 Profile, International Journal Of Renewable Energy Research Vol. 4, No. 1(2014) pp [2] Monir Chandrala, Abhishek Choubey and Bharat Gupta, Aerodynamic Analysis Of Horizontal Axis Wind Turbine Blade, International Journal of Engineering Research and Applications (IJERA) ISSN: Vol. 2, Issue 6, November- December 2012, pp [3] Chris Kaminsky, Austin Filush, Paul Kasprzak and Wael Mokhtar, A CFD Study of Wind Turbine Aerodynamics, Proceedings of the 2012 ASEE North Central Section Conference, 2012, pp [4] Yuji Ohya and Takashi Karasudani, A Shrouded Wind Turbine Generating High Output Power with Wind-lens Technology, Energies journal ISSN Vol. 3,( 2010) pp [5] H.S.Patil, Experimental Work on Horizontal Axis PVC Turbine Blade of Power Wind Mill, International Journal of Mechanical Engineering Vol. 2, Issue 2 (2013) pp [6] John McCosker, Design and Optimization of a Small Wind Turbine, Rensselaer Polytechnic Institute Hartford, Connecticut vol. 3, (2012) pp [7] Verónica Cabanillas Sánchez, Blade Performance Analysis And Design Improvement Of A Small Wind Turbine For Rural Areas, Proceedings of International Conference on renewable energy resources Vol. 3,(2013) pp [8] HoSeong Ji, JoonHo Baek, Rinus Mieremet and Kyung Chun Kim, Aerodynamic characteristics of an Archimedes spiral wind turbine blade according to the angle of attack change, Europe s Premier Wind Energy Event EWEA 2014, Barcelona, Spain Vol. 2, [9] M.C. Robinson, M.M. Hand, D.A. Simms and S.J. Schreck, Horizontal Axis Wind Turbine Aerodynamics: Three-Dimensional, Unsteady, and Separated Flow Influences, Proceedings of FEDSM99 3rd ASME/JSME Joint Fluids Engineering Conference San Francisco, Vol.1 July 18-23, 1999 pp