Control of Flow Structure over a Nonslender Delta Wing Using Periodic Blowing

The effect of unsteady blowing through the leading edge on the flow structure over a 45 deg swept delta wing in relation to the steady blowing is experimentally studied in a low-speed wind tunnel using the techniques of surface-pressure measurements, particle image velocimetry, and laser-illuminated smoke visualization. The unsteady blowing in the form of a periodic square pattern at 25% duty cycle is provided at the excitation frequencies varying from 2 to 24 Hz for a fixed momentum coefficient. The flow structure is characterized at Reynolds number Re = 3.5 x 10(4) for the angles of attack varying from 7 to 20 deg. The results indicate that unsteady blowing through the leading edges of the planform is quite successful in elimination of localized separation from the surface of the planform. In comparison with the steady blowing, the periodic blowing at relatively higher excitation frequency induces substantial improvement in flowfield and demonstrates superior performance even at significantly lower total momentum.