Impact of Turbulent Flow on H-Type Vertical Axis Wind Turbine Efficiency: An Experimental and Numerical Study

In light of the diminishing reserves of fossil fuels, the escalating threat of global warming, and stringent environmental regulations, renewable energy has risen to prominence in the global energy market. This study meticulously examines the influence of turbulent flow on the performance of H-Type Vertical Axis Wind Turbines (VAWTs), a crucial aspect in the context of aerodynamic load - a significant factor affecting the reliability and longevity of wind turbine systems. The investigation was carried out using a low-speed wind tunnel, measuring 0.3 mx0.3 m, representative of an open jet type inclusive of a power section, diffuser, stilling chamber, and contraction section, cumulatively extending 2.9 m in length. Wind velocities within the range of 1 to 30 m/s were generated by inverter-controlled, electric motor-driven axial fans. To simulate turbulence, wooden grids of varied sizes were strategically placed at the tunnel's entrance. It was observed that the smaller grid size resulted in a markedly higher turbulence intensity of 64.5%, in stark contrast to the larger and medium grids, which registered at 38.1% and 12.6%, respectively. A notable inverse correlation was discerned between turbulence strength and power coefficient. Specifically, at a wind velocity of 7 m/s, the power coefficient demonstrated a substantial decrease of 94.5%, 89.5%, and 67.4% when compared to conditions with no grid, a large grid, and a medium grid, respectively. This finding elucidates the inverse relationship between turbulence strength and power efficiency. Further insights were gleaned through Computational Fluid Dynamics (CFD) simulations, conducted using ANSYS Fluent 15.0 software. The 3D CFD model was intricately constructed utilizing the multi-physics ANSYS Workbench framework, which enabled an integrated workflow from CAD design to result post-processing. The simulation results revealed a direct correlation between increased wind speed and the amount of electricity generated, underscoring the nuanced interplay between wind velocity and turbine performance in turbulent conditions.