Active Flow Control of a Flame-Holder Wake Using Nanosecond-Pulsed Surface-Dielectric-Barrier Discharge in a Low-Pressure Environment

Abstract

Flame holders are widely used in ramjet combustors. We propose using surface nanosecond-pulsed surface-dielectric-barrier-discharge (NS-DBD) to manipulate the flame-holder flow field experimentally. The electrical characteristics, induced flow performance, and temperature distribution of NS-DBD were investigated via the electrical and optical measurement system. In the filamentary discharge mode, the discharge energy rose with decrease of the ambient pressure. The discharge pattern of NS-DBD changed from filamentous to uniform around 5 kPa. Starting-vortex intensity and jet-flow angle relative to the wall increased at low pressure. The recirculation zone was asymmetrical at pressures above 60 kPa. The recirculation zone’s area and length were smaller at lower pressures, but when the actuator was operating, the recirculation zone was nearly 11.8% longer. The vorticity increased with pressure. When the pulse width was 300 ns, the actuator had the greatest effect, and the low velocity region (LVR) area and the fuel–air-mixture residence time (FMRT) could be increased by 31.8% and 20.5%, respectively. The actuator had a smaller widening effect on the LVR area at lower pressure. Rising-edge time should increase with pressure to optimize LVR increase; it should be above 300 ns to optimize FMRT increase. We conclude that NS-DBD is a viable method of controlling flame-holder airflow at low pressure.