火箭出口面积对RBCC发动机引射模态影响规律分析

火箭基组合循环发动机引射模态飞行状态复杂,为了提高发动机的整体性能,研究了火箭出口面积对发动机引射模态的影响规律。通过数值模拟研究,引射流量在低飞行马赫数条件下,主要受引射性能影响,火箭出口面积越大,引射性能越好。然而,随着飞行马赫数的提升,引射空气的动能提升,隔离段内出现壅塞情况,引射流量主要受限于隔离段几何尺寸,与火箭出口面积无关。在亚声速工况下,火箭出口面积越小,发动机比冲越低,且出口无量纲面积为3.15时,火箭羽流膨胀撞壁,会引起性能骤减,需要予以避免;在超声速工况下,选择面积较小的火箭出口面积,燃烧室内压越高,发动机性能提升越明显。

Analysis of the influence of rocket exit area in RBCC engine under the ejector mode

In order to improve the performance of the rocket-based combined-cycle engine, the influence of the rocket exit area under the ejector mode was studied. Through numerical simulation research, the mass flow of captured air was mainly affected by the entrainment performance under the condition of low flight Mach number. The larger the rocket exit area, the better the entrainment performance. However, with the increase of flight Mach number, the kinetic energy of the entrainment air increases, and there is flow choking in the isolator. The mass flow of captured air was mainly limited by the geometric size of the isolator, independent of the rocket exit area. Under subsonic conditions, the smaller the rocket exit area is, the lower the specific impulse of the engine is, and when the exit dimensionless area is 3.15, the rocket plume will expand and impact the wall, which can cause a sudden reduction in performance. Under supersonic conditions, the smaller the rocket exit area, the higher pressure in the combustor, and the better performance of the rocket-based combined cycle engine.