Yuqian Chen

To address the challenge of flame stabilization over a flight Mach number (Ma∞) range of 1.5 – 2.0, an evaporative flameholder tailored for ramjet applications is employed under the low-temperature and low-pressure conditions characteristic of the combustor inlet. A three-dimensional RANS framework coupling dispersed-phase spray dynamics, kerosene chemistry, and radiative heat transfer is developed and validated against measured wall-pressure distributions and time-averaged flame structures obtained from a sector combustor experiment. Based on the validated model, two structural modifications are introduced to the prototype design: an increased combustor inner diameter and removal of the outer radial struts. Parametric simulations are subsequently performed for inlet total temperatures Tt,in = 320 to 480 K, inflow Mach numbers Main = 0.15 to 0.25, and inlet static pressures Ps,in = 0 to 100 kPa. The results show that removal of the outer radial struts weakens the compressive effect of the upper high-speed stream on the recirculation zone, leading to improved flame connectivity and overall stability. Additionally, increases in Tt,in and Ps,in enhance atomization and evaporation in both the main and pilot injection zones, while thedownstream gas-phase distribution is closely linked to the kerosene penetration depth. The fuel concentration in the recirculation zone first increases and then decreases with increasing Main, with optimal ignition occurring at approximately 0.225. Stable combustion is achieved at Tt,in = 320 K, with a total pressure loss below 10%, a relatively uniform exit temperature field, and high combustion efficiency. The downstream flame distribution depends strongly on the relative positioning of the main injector and the flameholder. Under low-temperature and low-pressure conditions, fuel impingement on the flameholder is essential to maintain flame connectivity.