火箭基组合循环发动机引射过程准一维分析方法研究

Quasi-One-Dimensional Method for Ejecting Process in RBCC Engine

关键词:  火箭基组合循坏发动机  引射流动  准一维方法  验证  引射比  临界背压

Key words:  RBCC engine  Ejecting flow  Quasi-one-dimensional method  Verification  Entrainment ratio  Critical back pressure

摘要:

为提高引射分析模型精度，从引射过程的物理机制出发，以速度差异导致的质量交换作为一、二次流掺混过程的控制因素，以一次流动量覆盖整个法向截面时的参数剖面计算引射效果，建立了引射过程分析方法，并采用数值模拟和试验结果对方法进行了验证。结果表明：一、二次流掺混过程的计算模型能反映法向截面上参数的变化趋势；当一次流处于过膨胀状态和轻度欠膨胀状态时，本方法计算的引射系数偏差在4.56%以内；当一次流处于严重欠膨胀状态时，在利用特征线法对截面静压进行校正以后，偏差在6%以内；以上精度均优于传统的Fabri模型。本方法还能准确地获得引射系统的临界背压，因此更适用于RBCC发动机这种有背压的应用场景。

Abstract:

To improve the accuracy of ejecting model， a new method is established based on the mechanism of ejecting process. The mass exchange caused by velocity difference between the primary and the second flow is selected to be the control factor， and the parameter profile at the section where the momentum of the primary flow covers the whole normal cross-section is taken to calculate the ejecting process. CFD and experiment results are used to verify the method. The comparison shows that the parameter profile calculated by this new method is approximate to the CFD results. While the primary flow is over-expanded and slightly under-expanded， the error of the entrainment ratio calculated by this method is 4.56%. While the primary flow is deeply under-expanded， the error of the entrainment ratio is 6% with the correction of pressure at the normal cross-section by characteristic method. And the precision is higher than conventional Fabri mode. This new method can calculate the critical back pressure accurately， so it is applicative for the RBCC engine.