Effects of Burst Ratio and Frequency on the Passage Vortex Reduction of a Linear Turbine Cascade Using a Dielectric Barrier Discharge Plasma Actuator

Abstract

A dielectric barrier discharge plasma actuator was employed to reduce the passage vortex generated in a turbine cascade. This study focused on the burst mode drive of a plasma actuator and examined the relationship between flow field changes and the burst ratio and frequency. The non-dimensionalized burst frequency was fixed at F+ = 1.26, and the burst ratio was varied from 0.01 (1% operation) to 1 (100% operation, continuous mode). Generally, an increase in the burst ratio weakens the passage vortex, and the center of the passage vortex moves more toward the upper endwall surface and blade suction surface side. However, the velocity distribution, secondary flow streamlines, turbulence intensity distribution, and vorticity distribution did not change proportionally with changes in the burst ratio. Furthermore, the burst ratio was fixed at BR = 0.5, and the non-dimensional burst frequency varied from F+ = 0.013 to 62.9. Low burst frequencies led to a decrease in the peak velocity of the passage vortex, vorticity at the passage vortex center, and negative peak vorticity; however, an increase in the distance of the center of the passage vortex from the upper endwall surface and the turbulence intensity at the vortex center was observed. In contrast, high burst frequencies resulted in a decrease in the position of the vortex center and the turbulence intensity of the passage vortex center, while the peak velocity of the passage vortex, vorticity at the vortex center, and negative peak vorticity increased. The non-dimensionalized burst frequency around F+ = 1 is appropriate because both effects are balanced.