RBCC引射模态气流抵抗反压能力受掺混程度影响研究

Effects of Mixing Level on Backpressure-Resisting Ability in Ejecting Mode of RBCC

关键词:  火箭基组合循环发动机  引射  掺混  二次流  引射比  反压

Key words:  Rocket based combined cycle engine  Ejection  Mixing  Secondary flow  Entrainment ratio  Back pressure

摘要:

为了获得气流的掺混效果与引射过程总体性能的关系，研究了轴对称引射流场中圆形和环形喷管的掺混程度及其对引射比和气流抵抗反压能力的影响。以一次流动量覆盖整个横截面位置为分界截面，将引射流场中的掺混分为上游掺混和下游掺混两个过程。研究表明，气流的引射效果以及抵抗反压能力几乎不受下游掺混过程掺混程度影响，而是由分界截面的掺混程度决定。上游掺混过程决定了分界截面的掺混程度，对引射过程的引射比以及抵抗反压能力有明显影响，分界截面位置的掺混程度越高，被引射的二次流流量越大，抵抗反压能力越弱。对于RBCC发动机引射模态，引射比和抵抗反压能力指标相互矛盾，不应以引射比为唯一目标。

Abstract:

In order to obtain the relationship between mixing level and performance of ejecting process， the mixing levels of circular nozzle and annular nozzle in axisymmetric ejecting flowfield and the influence on the entrainment ratio and resisting backpressure ability are studied. The ejecting flow field is divided into upstream mixing and downstream mixing by the section where the momentum of the primary flow covers the whole section， and the section is defined as demarcation section. Results show that the ejecting effect and resisting backpressure ability are affected little by the mixing level of the downstream mixing， but resolved by the mixing level of the demarcation section. The mixing level of the upstream mixing resolves the mixing level of the demarcation section， and influences the ejecting effect and resisting backpressure ability obviously. The higher the mixing level achieves at the demarcation section， the more secondary flow will be ejected， and the lower resisting backpressure ability will be. There is a contradiction between the entrainment ratio and resisting backpressure ability， so the maximum entrainment ratio is not the exclusive target in RBCC ejecting mode.