Control of Hypersonic BL Transition by Electrical Discharge (feasibility study)

Abstract

This paper presents experimental data characterizing the microsecond-scale electric discharge in hypersonic airflow. The tests are performed to prove the feasibility of such a discharge application to control the boundary layer (BL) at low static pressures in terms of transition and separation. Discharge developments are analyzed using electrical measurements, synchronized gate camera imaging, and a schlieren visualization. The results demonstrate that a shallow-cavity plasma actuator may be used for the BL tripping with a frequency F>100kHz even at static pressure Pst<5Torr.

Transient Plasma Impact on Spectra of Flow Disturbances in a Corner Separation Zone at Mach 4.5

“…A low level of gas density in a hypersonic boundary layer flow may cause an issue because in a low gas density environment the discharge strives to transit to a glow type discharge where the power density becomes too low for any observable effect. Preliminary tests [41] indicate that it is possible to generate filamentary plasma at the molecular concentration of > 2 × 10 17 3 using a simple two-electrode scheme. The Shallow Cavity Discharge actuator [41] has been used in these tests.…”

“…Preliminary tests [41] indicate that it is possible to generate filamentary plasma at the molecular concentration of > 2 × 10 17 3 using a simple two-electrode scheme. The Shallow Cavity Discharge actuator [41] has been used in these tests. It is flush mounted, with a size of a few millimeters, and can be installed on the metallic surface of the model.…”

“…A portion of this work (design of the SCD plasma actuator [41] ) was previously supported by MBDA-France (Mr. Francois Falempin supervision).…”

Measurement of Flow Perturbation Spectra in Mach 4.5 Corner Separation Zone

“…The SCD actuator [30] was used to generate artificial highfrequency disturbances in the flow. This discharge method allows for adjustment of the frequency of pulsed plasma operation for optimization in different flow conditions.…”

“…At F 50-100 kHz, the discharge worked as a push-pull plasma minijet. At lower frequencies of repetition, another operation mode was observed [30,31], currently considered as a cathode sheath pattern in which a thin layer of plasma covered most of the model surface. Typical records of the electric parameters in M 4.5 flow are shown in Fig.…”