Effects of input voltage and freestream velocity on active flow control of passage vortex in a linear turbine cascade using dielectric barrier discharge plasma actuator

Abstract

Passage vortex exists as one of the typical secondary flows in turbomachines and generates a significant total pressure loss and degrades the aerodynamic performance. Herein, a dielectric barrier discharge (DBD) plasma actuator was utilized for an active flow control of the passage vortex in a linear turbine cascade. The plasma actuator was installed on the endwall, 10 mm upstream from the leading edge of the turbine cascade. The freestream velocity at the outlet of the linear turbine cascade was set to range from UFS,out = 2.4 m/s to 25.2 m/s, which corresponded to the Reynolds number ranging from Reout = 1.0 × 104 to 9.9 × 104. The two-dimensional velocity field at the outlet of the linear turbine cascade was experimentally analyzed by particle image velocimetry (PIV). At lower freestream velocity conditions, the passage vortex was almost negligible as a result of the plasma actuator operation (UPA,max/UFS,out = 1.17). Although the effect of the jet induced by the plasma actuator weakened as the freestream velocity increased, the magnitude of the peak vorticity was reduced under all freestream velocity conditions. Even at the highest freestream velocity condition of UFS,out = 25.2 m/s, the peak value of the vorticity was reduced approximately 17% by the plasma actuator operation at VAC = 15 kVp-p (UPA,max/UFS,out = 0.18).