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

ABSTRACTThis paper presents a numerical investigation of the effect of DBDA length on filmcooling performance downstream a circular hole scheme over a gas turbine vanepressure side. The investigated scheme is that of a set of two DBDAs installeddownstream a cooling jet injection hole to damp the effect of the Counter RotatingVortex Pair (CRVP) accompanying the injected cooling jet. The simulation has beencarried out assuming one row of circular holes of a diameter D spaced at 4.5 D in thecross-stream direction and inclined at 22⁰ with the vane pressure side surface. Theactuators are located at 0.5 D downstream the injection hole and spaced at adistance = 0.25 D. Five cases of different electrode's length ranging from 1.5 D to 12D have been investigated under different applied voltages in the range from 10 kV to60 kV. In all those cases both the blowing and density ratios are assumed constantat values equal 1 and 2, respectively. Then, the effect of changing the blowing ratioon the performance has been studied for the case which exhibit optimumperformance where maximum surface effectiveness is achieved for specific actuatorlength and applied voltage. The obtained results show that, for each consideredactuator length, the surface average effectiveness was enhanced with the increase ofthe applied voltage to a certain limit where a maximum value was obtained, and thenthe effectiveness decreased with the increase of the voltage. The results indicate thatthis limit varies with the actuator length in such a way that, the longer the actuator thelower the voltage at which maximum surface average effectiveness occurs.