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

Takayuki Matsunuma,Takehiko Segawa

doi:10.3390/en13030764

Takayuki Matsunuma, Takehiko Segawa

Open Access

https://doi.org/10.3390/en13030764

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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).

Highlights

Axial-flow turbines are a main component of many modern turbomachines, and are commonly utilized in a vast array of industrial applications including aircraft propulsion jet engines, and electricity power generating gas turbines
As the input voltage increases from 12 kVp-p to 15 kVp-p, Figure 11h–k, the downward flows near the pressure side mid-passages increase in size and strength
Active flow control using a dielectric barrier discharge (DBD) plasma actuator was experimentally investigated as a potential technique for passage vortex reduction in a linear turbine cascade

Summary

Introduction

Axial-flow turbines are a main component of many modern turbomachines, and are commonly utilized in a vast array of industrial applications including aircraft propulsion jet engines, and electricity power generating gas turbines. The secondary flow, which is defined as the cross-flow deviated from the design freestream flow, gives rise to secondary vortices [1]. A passage vortex is a typical vortex in the secondary flow field among the turbine blades. The inlet boundary layer hits the leading edge of the blade, which leads to the formation of the horseshoe vortex. The pressure gradient within the turbine passage moves the pressure side leg of the horseshoe vortex towards the suction side of the neighboring blade, and causes the growth of a passage vortex.

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