基于等效热力过程的宽域冲压全流道性能设计方法

Full flow path performance design method for wide range scramjet based on equivalent thermodynamic process

为了开展宽域冲压发动机的全流道设计工作,将双模态冲压发动机等效热力过程分析方法拓展到全流道设计,建立了基于等效热力过程的宽域冲压全流道性能设计方法。将该方法应用于带几何可调进气道的宽域冲压发动机全流道方案设计,分析了进气道调节、燃烧室尺寸对发动机性能潜力的影响。研究结果表明:马赫数2.0~3.5范围,在比冲和流量2个因素之间,流量对发动机推力性能影响更大,所以在低速段应尽力增大进气道流量;与第2级转折角相比,第2级折转角对比冲和推力的影响权重更大,采用较小的2级折转角有利于提高性能;获得最优推力和比冲性能需要不同的进气道方案。在所研究的马赫数范围,燃烧室需用面积相差很大,飞行马赫数越低、需用面积越大。若以低马赫数的高推力要求为设计依据,需要付出横向尺寸的代价,意味着阻力和重量的增大;若以高马赫数的高推力要求为选择依据,需要在低马赫数时付出推力性能的代价,意味着加速时间和耗油量的增大。本文发展的方法可以快速筛选获得最优推力性能或比冲性能的全流道方案,为宽域高性能冲压发动机的全流道性能初步设计提供有力支撑。

The analysis method based on equivalent thermodynamic process is extended to establish a full flow path design method for wide range scramjets.This method is subsequently applied to the design of the full flow path for a wide range scramjet with a variable geometry inlet.Effects of adjustment and combustor size on the engine perfor⁃mance are analyzed.The results show that the inlet mass flow rate has a larger influence weight on thrust than on spe⁃cific impulse in the range of Mach number 2.0-3.5;thus,best efforts should be made to increase the inlet air flux at the low speed stage.The second compression angle has a larger influence on the engine specific impulse and thrust than the third compression angle.For the given examples in this paper,engine performance benefits from smaller angles of the second compression ramp.The inlet configuration with the optimal thrust is different from that with the optimal specific impulse.The corresponding combustor area also varies dramatically with the flight Mach number if the optimal performance is desired,with higher velocity requiring smaller area.If the high thrust at a lower speed is wanted,the penalties of combustor dimension must be paid at a higher speed,meaning more drag and weight.If high thrust at a higher speed is wanted,the penalties of thrust at lower speeds must be paid,meaning more acceleration time and fuel consumption.This method can rapidly find the flow path scheme with the optimal thrust or specific im⁃pulse by comparing massive options,therefore providing strong support for the high performance scramjet preliminary design.