Aerodynamic Design and Analysis of Low Speed 500 kw Wind Turbine Blade for Indian Conditions

Transcription

1 Aerodynamic Design and Analysis of Low Speed 500 kw Wind Turbine Blade for Indian Conditions Vidyadhar Y. Mudkavi and Prodyot K. Dutta Computational and Theoretical Fluid Dynamics Division National Aerospace Laboratories, Bangalore INDRU Kick-off Meeting, December 05-06, New Delhi, India

2 Outline Introduction India s s Position in wind power generation India s s Wind Potential The Design Wind Speed Indian Conditions NAL Initiative Tools and technologies Concluding Remarks

3 Introduction Impending depletion of non-renewable energy sources like fossil fuels has prompted exploration of other renewable sources (bio-mass, sun, water and wind). Other than the solar energy, wind is next best form of energy. Poses some engineering challenges owing to variable nature (Intermittency). Only recently this form of energy is being exploited. India stands fourth (after Germany, USA and Spain) in the world in wind energy generation (3% of total). Currently installed wind turbines in India are based on imported technologies that cost about INR 50 million per MW.

4 India s s Position Rank Installed Wind Power Capacity (MW) [16][17] Nation Germany Spain United States India Denmark (& Færoe Islands) China ,415 10,028 9,149 4,430 3,136 1, ,622 11,615 11,603 6,270 3,140 2,604 Latest 21,283 12,801 13,885 7,231 2,956 Source: Wikipedia. Refs: [16] [17] documents/publications/statistics/070129_wind_map_2006.pdf

5 India s s Wind Potential Some estimates put this at 45,000 MW. Must note that there is no official Wind Atlas available for India. This estimate, therefore, is of no consequence. Wind Atlas Project is now in progress and must wait for correct estimates.

6 The Design Wind Speed Wind turbine is a sophisticated machine like any other and as such must be designed with care. Like any engineering system, wind turbines are designed around a specific wind speed known as the Design Wind Speed. A design requirement is that the power must vary like the cube of wind speed up to the design wind speed and flatten after that. The Design Wind Speed is an important parameter.

7 Indian Conditions Being in the tropics, wind speeds are lower (Design wind speed ~ 12 m/s). Wind speeds in upper latitudes much higher (Design wind speed ~ 20 m/s). Imported turbines will operate sub- optimally: Power varies as cube of wind speed. Power extracted is just quarter of rated power! Site specific design is necessary.

8 About NAL Premier aerospace research institute Major Activities in the areas of: Fluid Mechanics (Experimental and Computational) Structures (Composites, Fatigue etc) Propulsion Wind Energy Atmospheric research Materials Flight Mechanics Aerospace Electronics Major test facilities (Wind Tunnels, ATF, Fatigue)

9 NAL Initiative Design and develop 500 kw low speed wind turbine: 500 kw is most optimal (NAL study) Two bladed Downwind Tilt-tower tower (maintainability) Stall regulated Teetered Spin-off from aerospace (gurney, winglet, composites)

10 Partners NAL is playing the lead role: Wind Energy Division Computational and Theoretical Fluid Dynamics Division Propulsion Division Fibre Reinforced Plastics (FRP) Division Engineering Services Division SERC, Chennai for structural aspects Sangeeth Group of Companies industrial partner

11 Tools and Technologies CFD based tools for blade analysis Inverse design methods for blade profile design Aerospace composites technology Novel foundation design (Civil engg) Novel tower design Generator and gearbox outsourced All technologies proprietary to NAL to be revealed after patenting

12 The 500 kw NAL Wind Turbine

13 Aerodynamic Analysis Tools A simpler Panel Method Quick design estimates Employed mainly for aerospace applications Extension with quasi steady approximation Reynolds Averaged Navier-Stokes (RANS) unsteady codes Capable of handling complex flows Detailed flow fields Turbulence models

14 Panel Method Thrust (Panel) Thrust (Panel) * 0.8 IMP RANS Thrust (K Newton) Wind Speed(m/sec) Power ( K Watt) Power(Panel) Power(Panel) * 0.5 IMP RANS Wind Speed(m/sec)

15 IMPRANS Implicit RANS Unsteady Simple turbulence model (Baldwin-Lomax Lomax) Analysis in inertial frame Nodal point scheme Finite volume Dual time stepping (acceleration)

16 Schematic V w z θ c pc V dw θ tilt y, y z β Ω c Ω rcosθ A A V w sinθ β θ pc r z x r O x r R

17 Sample Results C x' kN C y' kN Unsteady forces and moments for a 500kW wind turbine blade at a wind speed of 12m/s P = kW T = 40.71kN C z' C My' kW 3.31kN C Mx' kNm C Mz' kNm β (deg.) β (deg.) Fig. Unsteady turbulent loads and moments on a 500kW wind turbine blade during the second cycle. Blade radius R = 22.5m; θ tilt = 2 O ; θ pc = 6 O ; ΩR/V w = 6.67; M tip = 0.23; Re tip = 5 million per metre. Magenta line: Average value.

18 Flow Fields

19 Flow Fields r=3.047m r=5.186m r=7.031m r=9.400m r=12.322m r=15.276m r=17.245m r=19.953m r=22.002m r=22.500m Fig. Relative streamtraces at different radial stations on NAL' s 500kW wind turbine blade. Tilt = 2 deg.; Precone = 6 deg.; Tip speed ratio = 6.67; M = 0.23; Re = 5 million/m.

20 300 kw in operation Two sets of blades manufactured using NAL composites technology Enhanced performance Lighter Wind turbines are operational at Kethanur near Coimbatore

21 Concluding Remarks Site specific designs are essential for optimal extraction of wind energy. Wind turbines employing high end technologies will be more economical and effective. NAL has a programme to develop 500 kw turbine specific to Indian Conditions. Design and analysis tools are in place. Aerospace design and manufacturing technologies are being employed. New turbine will be operational in a few months. Field trials will lead to optimization exercise.

22 Acknowledgements The development of wind turbine was financially supported under the New Millennium Indian Technology Leadership Initiative (NMITLI). We acknowledge this support.

23 Thank You

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25 Flow Fields