Numerical Investigation of the Effect of Dielectric Barrier Discharge Actuator (Dbda) on Film Cooling Performance Downstream a Circular Hole Scheme Over a Gas Turbine Vane Pressure Side

Abstract

This paper presents a numerical investigation of the effect of DBDA length on film cooling performance downstream a circular hole scheme over a gas turbine vane pressure side. The investigated scheme is that of a set of two DBDAs installed downstream a cooling jet injection hole to damp the effect of the Counter Rotating Vortex Pair (CRVP) accompanying the injected cooling jet. The simulation has been carried out assuming one row of circular holes of a diameter D spaced at 4.5 D in the cross-stream direction and inclined at 22 ⁰ with the vane pressure side surface. The actuators are located at 0.5 D downstream the injection hole and spaced at a distance = 0.25 D. Five cases of different electrode's length ranging from 1.5 D to 12 D have been investigated under different applied voltages in the range from 10 kV to 60 kV. In all those cases both the blowing and density ratios are assumed constant at values equal 1 and 2, respectively. Then, the effect of changing the blowing ratio on the performance has been studied for the case which exhibit optimum performance where maximum surface effectiveness is achieved for specific actuator length and applied voltage. The obtained results show that, for each considered actuator length, the surface average effectiveness was enhanced with the increase of the applied voltage to a certain limit where a maximum value was obtained, and then the effectiveness decreased with the increase of the voltage. The results indicate that this limit varies with the actuator length in such a way that, the longer the actuator the lower the voltage at which maximum surface average effectiveness occurs.