Liquid-Fuel Behavior in an Aeronautical Injector Submitted to Thermoacoustic Instabilities

The aim of this work is to study the role of the liquid phase in the thermoacoustic coupling, which subsequently leads to combustion instabilities. Experimental investigations were performed on an actual multipoint spray injector geometry used in real aeronautical combustors. A test bench was specifically designed with continuously changeable acoustics conditions, which allows obtaining of a stable or an unstable flame for identical flow conditions. Different laser-based visualization techniques were used to analyze the kerosene spray (both liquid and vapor phases) and the heat released from the flame. A phase-averaged data processing of the planar laser-induced fluorescence images reveals the complex unsteady behavior of the liquid phase, its coupling with pressure fluctuations in the chamber, the heat released from the flame. The origins of the spray fluctuations are also analyzed.