Seminar: Cavity Flow Control for Scramjet Applications

Unstart prevention is a critical part of maintaining stable scramjet operation. An isolator is typically used to perform this function. A resonating cavity could potentially augment the back-pressure margin of an isolator; however, there is an associated drag penalty. The base-geometry of the cavity (prior to control) also has an effect on its ability to augment the back-pressure margin of an isolator. This work has investigated the ability of Localized Arc Filament Plasma Actuators (LAFPAs) to control supersonic cavity resonance and the ability of controlled cavities of various geometries to augment the back-pressure margin of an isolator. Additionally, preliminary work on the LAFPAs’ ability to reduce the cavity drag has been performed. The LAFPAs’ control authority will be used in conjunction with downstream sensors and feedback control algorithms to reduce the cavity drag as much as possible during normal operation of a scramjet engine. However, when the control algorithm detects that unstart is imminent the actuators will control the cavity to provide the greatest additional back-pressure margin, thereby paying a drag penalty temporarily to prevent inlet unstart.

Schlieren and time-resolved static pressure measurements have demonstrated the efficacy of the cavity in increasing the model-isolator back-pressure margin by up to 20%. In particular, it was observed that the geometry of the cavity has a larger effect on the increase in back-pressure margin than control and that cavity length was the most important parameter with shorter cavities yielding better results. Additionally, preliminary PIV measurements have demonstrated the actuators’ ability to change the cavity drag by a factor of 2.

Hosted by Professor Jim Gregory