Int. J. Mech. Eng. & Rob. Res. 2012 Hari Pal Dhariwal et al., 2012 Research Paper ISSN 2278 0149 www.ijmerr.com Vol. 1, No. 3, October 2012 2012 IJMERR. All Rights Reserved PREDICTION THE EFFECT OF TIP SPEED RATIO ON WIND TURBINE GENERATOR OUTPUT PARAMETER Hari Pal Dhariwal 1 *, Dharampal Yadav 1 and Barun Kumar Roy 2 *Corresponding Author: Hari Pal Dhariwal, hpdhariwal@gmail.com In wind turbine design blade and speed of rotor is one of the most important parts. Power obtained from the wind can only be extracted when a better design with increased rotor speed. Generator selection and its power can be calculated easily which is important factor for wind turbine design. Keywords: Tip Speed Ratio (TSR), Revolution Per Minute (RPM), Horizontal Axis Wind Turbine (HAWT) INTRODUCTION Wind is caused by uneven heating and cooling of the earth s surface and by the earth s rotation. The amount of energy produced by a wind machine depends upon the wind speed and the size of the blades in the machine. In general, when the wind speed doubles, the power produced increases eight times. Larger blades capture more wind. As the diameter of the circle formed by the blades doubles, the power increases four times. A best tip-speed ratio depends on the number of blades in the rotor. The fewer blades, the faster the wind turbine spins to extract maximum power from the wind. Early experiments showed that a two-blade rotor has an optimum tip-speed ratio of about 8, a threeblade design about 6, and four blades, about 4. However, more recent highly efficient aerofoil designs have increased the numbers by 25 to 30%, which allows increasing rpm and therefore generating more power. Serhat (2005) investigated aerodynamic design of HAWT blades. Wind turbine blades are the pivot of the other parts of a wind turbine in electricity production since they extract the energy from the wind and carry this energy to generators which produce electricity. David and Daniel (2003) worked on the blades of a modern wind turbine are key 1 Singhania University, Rajasthan, India. 2 OITM, Hisar. 125
components, central to all aspects of the system from energy capture to system dynamics to tower clearance. They are also complex structural items, typically comprising many layers of fiber reinforced material with necessary shear webs, root fixtures, and tapering cross sections. Implementation of design improvements within the wind turbine industry was hampered by the lack of practical prediction tools having the appropriate level of complexity. (Bermúdez et al., 2002). Wind turbine design graduated from the airfoil design industry with much of the same theory being applied. Based on the observations in past, work was done in large size wind turbine blades. As large size turbines will produce more power. Methodology and Detail of the Program Designed for Calculating Various Wind Turbine Parameters A Program is designed by me in VB.NET language for the fast calculation and can find out desired result in short time. Figure 1 shows the image of the Program which I named as Blade Calculator. The Important features of this program are: Code works on click of a button Calculate Output. On click of button 2 functions are called caloutput, drawtable and output panel is made visible. In this code 3 functions are used. Caloutput(): In this function all the out put values are calculated and assigned to desired lables to display the out put on form. Figure 1: Image of Blade Calculator 126
Drawtable(): In this function table containg radius, chord and beta has been drwan using Table Layout Panel control of Visual studio 2005. Getdatafromexcel(): In this function we find the value of sin( ) from the excel file sintbl.xls (attached) on the basis of Angle od Attack ( ) to calculate Coefficient of Lift in caloutput() function. Code, excel and image of form design is attached. RESULTS AND DISCUSSION Effect of TSR Case 1: Data is calculated by taking various values shown below: No. of Blades = 2 Blade Radius = 0.8 (in meter) Blade Efficiency = 0.35 TSR = 6 Wind Speed = 10 m/s Angle of Attack = 4 Degree Then Click on the designed software Calculate Output Output Parameters will display Power = 430.8 Watt RPM of Generator = 716 RPM Generator Torque = 6.01 Nm Coefficient of Lift = 0.438 Data are shown in Figure 2 given below. Figure 2: Blade Calculator for Case 1 127
Case 2: Here TSR changes to 7, then Data are shown in Figure 3 below. Case 3: Here TSR changes to 8, then Data are shown in Figure 4 below. Figure 3: Blade Calculator for Case 2 Figure 4: Blade Calculator for Case 3 128
Figure 5: Blade Calculator for Case 4 Table 1: Effect of TSR on RPM Inputs Case 1 Case 2 Case 3 Case 4 No. of Blades (N) 2 2 2 2 Radius of Blade (r) 0.8 0.8 0.8 0.8 Efficiency ( ) 0.35 0.35 0.35 0.35 TSR 6 7 8 9 Wind Speed (U) 10 11 12 13 Angle of Attack ( ) 4 4 4 4 Outputs Case 1 Case 2 Case 3 Case 4 Power in Watt 430 573 744 946 RPM of Gent. 716 919 1146 1397 Gent. Torque 6.01 6.2 6.4 6.7 Coef. of Lift 0.438 0.438 0.438 0.438 129
Figure 6: Tip Speed Ratio v/s RPM of Generator Case 4: Here TSR changes to 9, then Data are shown in Figure 5 below. As seen from the Table 1, as the TSR is Increased RPM of the Generator is also increased shown by the graph in Figure 6. CONCLUSION Based on the observations RPM of the generator shaft is directly proportional to the TSR. Higher the TSR there will be an increase in the power output. This can be achieved by a better design of the wind turbine blade. REFERENCES 1. Bermúdez L, Velázquez A and Matesanz A (2002), Viscous-Inviscid Method for the Simulation of Turbulent Unsteady Wind Turbine Airfoil Flow, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 90, pp. 643-661. 2. David J Malcolm and Daniel L Laird (2003), Modeling of Blades as Equivalent Beams for Aeroelastic Analysis, AIAA Reno January, #0870. 3. Dhariwal Hari Pal (2010), Wind Turbine Design a Feasibility Study and Scope of Improvement, Soch-Masthnath Journal of Science and Technology India, Vol. 5, pp. 6-10. 4. Puneet Manwell J F, McGowan J and Rogers T (2002), W ind Energy Explained: Theory, Design and Application, University of Massachusetts, Amherst, MA. 5. Seraht Duran (2005), Computer-Aided Design of Horizontal -Axis Wind Turbine Blades, Middle East Technical University. 130