Flow field and combustion field control using pylons installed upstream of a cavity in supersonic flow

This study clarifies the flow field and flame structure of a cavity flameholder with pylons in a Mach 2.8 airflow. A burned hydrogen/air gas mixture, rich in fuel, was injected in supersonic combustion experiments because self-ignition of fuel is difficult in a mainstream with low enthalpy. Experimental data were collected using the shadowgraph method, direct photography of the flame, wall pressure measurement, and OH Planer Laser-induced Fluorescence (OH-PLIF) measurement. In addition, three-dimensional numerical simulation was conducted. When one pylon was installed upstream of the jet flow, the penetration height of the jet increased, and a flame was formed in the mainstream center. When two pylons were installed at the front edge of the cavity, the flow field inside the cavity differed depending on the distance between the pylon and jet flow. The ignition and combustion of the burned-gas were suppressed at a close distance between the pylon and jet flow. For a large distance between the pylon and jet flow, the ignition and combustion of the burned-gas was enhanced. When hydrogen was injected as the main fuel from the upstream of the cavity, ignition of the main fuel was successful only for a large distance between the pylon and jet flow.