VISUALIZATION OF UNSTEADY FLOW PHENOMENA OF WELLS TURBINE DURING HYSTERESIS STUDY

摘要

To visualize the flow field around the blade of the Wells turbine during hysteresis, experimental and numerical investigations were made including deep stall condition of the Wells turbine. The experimental investigation was made using a turbine-equipment with a simulated sinusoidal flow condition. The numerical investigation was made by an unsteady three-dimensional Navier-Stokes numerical simulation. A counterclockwise hysteretic loop is observed in unstalled condition, which can be associated with a streamwise vortical flow appearing near the blade suction surface. Besides, a clockwise hysteretic loop is observed in deep stall condition, the flow structure of which can be considered similar to that of the dynamic stall of an airfoil.