| Title |
Aerodynamic force evaluation of Pointed Tip Wind Turbine Blade Using CFD |
| Authors |
Lee, Kyoung-Soo ; Huque Ziaul ; Han, Sang-Eul |
| Keywords |
Renewable energy ; Wind turbine blade ; NREL Phase VI ; CFD ; Pointed tip ; Aerodynamic force |
| Abstract |
This paper presents the pointed tip effects on the aerodynamic load of The National Renewable Energy Laboratory (NREL) Phase VI wind blade rotor. The aerodynamic loads around flow field are evaluated using 3D CFD simulation. The commercial ANSYS CFX and parameterized 3D cad models of NREL Phase VI are used for the analyses. The Shear Stress Transport (SST) turbulence model and 0-degree yaw angle condition are adopted for CFD analysis. Nonlinear twist angles were adopted for the effects of nonlinear resultant wind speed. The linearly tapered shape was made by reducing the chord length linearly to the tip region. To find out the 3D aerodynamic effects, sectional pressure coefficient and integrated forces about primary axis, which are normal, tangent, thrust and torque, are evaluated. 7 wind speed cases (5m/s, 7m/s, 10m/s, 13m/s, 15m/s, 20m/s, 25m/s) with constant blade rotating speed (72 RPM) are considered. The pointed tip shape was made by reducing the original NREL chord length gradually near the tip region. The numerical difference of Cp on wind blade surface between original and modified pointed tip models is negligible except near tip region, and also shown good agreement with experimental result in low wind speed case. From the CFD simulation for pointed tip shape, the decreased value of surface integrated torque about primary axis are obtained because of the reduced surface area in pointed tip region, but it is negligible compared to total values. Rather it can help to increase the structural stability and reduce the vortex because of the reduced force coefficient on near the tip region. |