Numerical Investigation of Combustion Regime and Heat Release Characteristics in RBCC Engine Under Different Dynamic Pressures

The dynamic pressure is an important ballistic parameter that affects the operating characteristics of the air-breathing engine. For the purpose of extending the flight envelope, investigating the performance of RBCC engine under different dynamic pressures is of considerable value. The reactive flow is numerically investigated using an Improved Delayed Detached Eddy (IDDES) method. Three operating schemes with different dynamic pressures of 40, 60 and 80kPa are comparatively studied. Increasing dynamic pressure causes the supersonic flow region to be more significantly compressed, a phenomenon that results in a drop in the total flow field velocity, as demonstrated by the results. With dynamic pressure elevation, turbulent behaviors in the recirculation region are notably intensified. As dynamic pressure rises, the high adverse pressure gradient promotes the extension of the recirculation zone, thereby causing an expansion of the subsonic combustion area and a progressive increase in global combustion intensity. Additional analysis of the spatial distribution of combustion products demonstrates that an elevation in dynamic pressure can improve combustion efficiency within the combustor. According to statistical analysis, the subsonic heat release mode dominates the whole combustion heat release process, and the subsonic combustion intensity increases significantly with the increase of dynamic pressure. The heat release mode within the second stage combustor is more widely distributed than the first stage combustor.