Flow Control in Supersonic-Cavity-Based Airflow by Quasi-Direct-Current Electric Discharge

This experimental study examines flow control authority of a quasi-DC (Q-DC) electric discharge in a cavity-based supersonic flow. Testing was performed with Mach 2 airflow using the Research Cell 19 facility at the U.S. Air Force Research Laboratory while varying pressure (P-0 = 2.3-4.5 bar), temperature (T-0 = 290-590 K), gaseous fuel-injection rate [iii = 0-3000 standard L/min (SLPM)1, and power of the electric discharge (W-pl = 14-22 k W). Schlicren imaging and pressure sensors were used to study changes to the flowfield and wall pressure distribution over the test section. 'the Q-DC electric discharge generates a shock wave that impinges on a rear-facing cavity and increases the pressure throughout the cavity up to 5%. A gas was injected upstream of the cavity to represent fuel injection in a scramjet engine. The flowfield changes due to the Q-DC discharge interaction with the fuel-related bow shock wave, and shifts the shock train upstream. Fur injection rates of rit = 1500-3000 SLPN1, the Q-DC discharge shifts the bow-shock reflection forward to impinge the cavity, thus showing a synergistic effect of the Q-DC discharge and the upstream injection. The maximum relative pressure increase during Q-DC operation with injection was similar to 11%. The control effectiveness parameter q was defined and is approximately constant across the tested flow conditions.