Oscillation phenomena at gas fuel injection in supersonic cross-flow

At the Laboratory of Supersonic Flow and Combustion Control (headed by Dr. Leonov), plasma-assisted combustion (PAC) is a significant research area. An increasing interest in Plasma-Assisted Combustion is motivated by a necessity to promote chemical reactions at unfavorable conditions such as far-from-stoichiometric composition, poor mixing, low gas temperature, high flow velocity, etc. With few exclusions, scientific and engineering research regarding PAC is still in the fundamental phase in general, and in the data accumulation phase for the case of supersonic environments particularly. A major expectation on how plasma could be employed for improvement of supersonic combustion (realized in scramjet engine) is due to its ability to promote the fuel ignition and support chemical reactions at low gas temperature in a wide range of pressure and fuel concentrations. Three main ideas underlie the concept of PAC in supersonic flow with direct fuel injection: (1) control of flow structure in the vicinity of the reaction zone; (2) gas heating and non-equilibrium excitation of fuel and oxidizer by the discharge in a mixing layer; and (3) fuel-air mixing enhancement due to flow instability generation. The latest point is the subject of the current Project.

Many researchers have studied the resonance phenomenon in nozzle flows in the past for academic reasons as well as because of its importance to a wide variety of engineering applications, ranging from mixing and jet noise control to buffeting in external flows and rocket engine instability. An external unsteady load or self-excitation can cause resonance, or a combination of both. The current Project major objective is to explore, theoretically and experimentally, the spectra of natural and stimulated oscillations in s cross-flow injected secondary gas through a sonic nozzle.