CFD and experimental investigation of a diffuser-deflector assisted Persian VAWT for urban and industrial airflow energy harvesting

Abstract

Recovering unused kinetic energy from urban and industrial airflow systems provides a potential approach for decentralized renewable energy generation. This study investigated the performance of a Persian Panemone vertical-axis wind turbine (VAWT) integrated with a diffuser and adjustable deflector for airflow energy recovery in confined environments. Computational fluid dynamics (CFD) simulations and laboratory experiments using fan-generated airflow were conducted to evaluate the effects of blade number and airflow conditions on turbine performance. Five- and six-blade configurations were evaluated under different wind speeds. CFD results showed that the 5-blade configuration achieved the highest power coefficient (Cp) of 0.2332 at 2 m/s and maintained a tip speed ratio (TSR) of approximately 1.9. Velocity and pressure contours indicated that the diffuser accelerated the incoming airflow and improved momentum transfer to the rotor. In the experiments, the 6-blade configuration exhibited better starting characteristics, reaching a maximum no-load rotational speed of 260 rpm compared with 213 rpm for the 5-blade configuration. The difference between CFD and experimental results was attributed to non-uniform fan-generated airflow, mechanical friction, electrical loading, and idealized numerical assumptions. The results indicate that the 5-blade configuration provides more favorable aerodynamic performance, whereas the 6-blade configuration provides better starting and rotational characteristics under the tested laboratory conditions. The diffuser–deflector system therefore provides a potential approach for recovering energy from confined urban ventilation and industrial exhaust airflow.