CFD Evaluation of Hawt for Operations in Low Wind Speed Regions /

Abstract

Small scale wind turbines can produce power in low wind speed regions and provide them with energy security. In this research, BEMT designed 1kW HAWT is studied for its coefficient of performance and flow field around the turbine using 3D Computational Fluid Mechanics (CFD). Reynolds Averaged Navier Stokes (RANS) equations based numerical simulation is used in this analysis. The turbine blade radius is 1.21 m and the rotor has three blades. To reduce the computational power, only one blade is simulated using the periodicity assumptions in multiple reference frame model. The model is designed in SolidWorks and the grid is generated using POINTWISE mesh tool, employing the T-REX function, mesh independent results are obtained at 10 million elements around single blade. Kω -SST model is employed to model the turbulence. All the simulations are performed in ANSYS CFX package. A detailed selection of results is presented using the ANSYS post-CFD package and TECPLOT 360. The results are validated by comparing the coefficient of performance (Cp) obtained through CFD results and Cp published from BEMT analysis. The Cp of 1 kW rotor from BEMT is 0.48 whereas the Cp obtained from CFD analysis is 0.47, the decrease in Cp through CFD is associated with the rotational losses accounted in the CFD analysis. The simulation results include the Pressure distribution, Velocity distribution along the flow direction at different span ratios, wake behind the rotor, surface streamlines on the turbine blade, turbine power and the torque produced on the rotor blade. The analysis also includes the effect of wind speed on the turbine power.