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Computation and Analyses on the Aerodynamic Performance of a Horizontal Axis Wind Turbine Blade

Author: TongGang
Tutor: YangCongXin
School: Lanzhou University of Technology
Course: Fluid Machinery and Engineering
Keywords: Wind turbine Blade Aerodynamic performance Numerical computation Limitde streamline Rotational effects
CLC: TK83
Type: Master's thesis
Year: 2011
Downloads: 238
Quote: 3
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Abstract

As the renewable energy, wind power more and more gets the world’s attention. The flow around the S809 for a wind turbine airfoil and NREL Phase VI blades is studied and analysed using the numerical computation in the thesis.Finite volume method and SIMPLE method are used. The influence of the size of computational domain and grid scale on the accuracy of numerical computation is researched,and a suitable size is obtained. The possibility of simulating the fluid field around the airfoil and wind turbine blades with different turbulence model is researched, and the appropriate turbulence model for the calculation is reaped. The flow characteristic on the static stall and dynamic stall of the airfoil is calculated and researched using the unsteady solver. The flow around the wind turbine blade is simulated using the DES model and sliding mesh method, the limited streamlines on the blade’s surface、the pressure coefficient distributions at the different blade elements and the torque coefficient distributions along the blade axis are discussed. The main contents in the paper are concluded as the follows:(1) Dynamic lift coefficient of the airfoil is larger than the static lift one in the upstroke process in the stall region, whereas is opposite during the downstroke motion. With the increases of the oscillation amplitude、the mean angle of attack and the reduced frequency, the hysteresis effect becomes more significant.(2) The flow around the wind turbine blades is computed withκ-ωSST turbulence model and Multiple Frame Reference under the low wind speed condition, it is shown that numerical data have a good agreement with the experimental ones. The numerical calculation using the DES method and sliding mesh under the higher wind speed condition is done, the same consequence comes out.(3) Under the low wind speed, the separated flow around the different blade’s element doesn’t occur along the inflow direction; the similar phenomenon happens along the blade axis. But under the higher wind speed, the separated flow around the inboard sections comes out where the fluid flows along the span wise.(4) The torque coefficient distributions along the blade axis change with the inflow wind speed; under the lower wind speed, the trend with setting after rising from the boot to tip is presented, and reaches maximal value at the near r/R=0.80; it is shown that the torque of the wind turbine blade mainly concentrates during the r/R= 0.6-0.8. Under the higher, the double peaks for the torque coefficient occur along the span wise; the minimum Value arrives at the near r/R=0.60, whereas the maximum one at the r/R=0.8.(5) The flow partially separates as the wind speed grows. The centrifugal and Coriolis forces lead to the lift augment and delay stall as a consequence of blade rotation. The lift coefficient is one times under 3D rotation than 2D condition with the same Reynolds and angle of attack.The accurate prediction for the aerodynamic performance of wind turbine rotor is a key in its aerodynamic design. Through the research on the flow around the airfoil and wind turbine blades by the numerical computation, CFD methodology can shown great promise to well predict airfoil dynamic characteristic and wind turbine blade aerodynamic performance, these can greatly help better understand the complex dynamic stall and three rotational effect’s model occurring on the wind turbine blades.

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CLC: > Industrial Technology > Energy and Power Engineering > Wind energy, wind machine > Wind machinery and equipment
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