Optical Diagnostics in a High-Pressure Combustor with Gaseous Oxygen and Kerosene

Abstract

This paper presents analysis of results from optical diagnostics in a high-pressure combustor burning gaseous oxygen (GOX) and liquid kerosene RP-2 fuel through a jet-swirl coflow injector. The objectives of the experiment were to measure flame stabilization and position under high-pressure conditions. Data were obtained at pressures from 2 to 16.5 MPa and mixture ratios from 2.9 to 20. High-speed cameras captured side-on chemiluminescence and infrared images of the flame. Results show that the flame-spreading angle from the injector ranges from approximately 3 to 6 deg, varying with pressure and propellant mass flow rate. A novel borescope was used to image the flame from upstream of the GOX post, enabling visualization of the flame near its stabilization location. The flame stabilization characteristics change significantly with the fuel flow velocity (which is proportional to pressure). At low pressures and fuel flow velocities, the flame appears to be distributed azimuthally in a nearly axisymmetric manner. At higher velocities, helical spirals of luminosity develop near the GOX post. In addition, the side-on views reveal concentrated streaks of, presumably, fuel entering the combustion chamber. These results suggest that computations must resolve the individual fuel injection orifices, to capture the flame stabilization.