可变边界燃烧的扰动对驻定爆震火焰面稳焰性能影响的机理研究

Supersonic combustion indicates that the mixing, ignition and stable combustion occur in limited space and time. To get sufficient residence time, the combustor is usually designed too long; as a result, combustion enhancement and flame holding have always been a key issue and difficulty of supersonic combustion. Turning diffusion combustion-deflagration from the conventional scramjet to detonation in order to reach the maximal limits of scramjet and can shorten length of combustor by a standing stabilized detonation wave are of practical interests for supersonic combustion and alternatives to scramjet at high Mach flight mission . However, the existed scenarios can’t work under the dual-mode or have the longer mixing zone or under relatevie narrow operation region. The present proposal is to initiate a standing detonation by using an alterable wedge and to reach maximal efficiency of scramjet, based on the pervious study on shock wave interaction with reactive turbulent flow, possible approach for key issue of the proposal is suggested. This proposal is focused on the particular boundary conditions related to propulsive performance of hypersonic vehicle. The critical condition and stable mechanism of shock-induced detonation and the interaction between induction reaction zone and detonation front are to be explored, the results are to provide the primary theoretical basis for the innovation of a novel supersonic combustion propulsion. This project aims to address key technologies including minimal initial energy of shock- induced detonation within a limited space of propulsion system, the mechanism of shock wave coupled with combustion wave and verification of numerical modeling and high-order schemes for capturing detonation wave.

面向空天飞行器组合动力的激波诱燃冲压发动机是超燃冲压迈向更高马赫数的技术方案，其关键技术是双模态下在弱激波时如何强化激波生成与稳定，实现激波诱燃冲压爆震燃烧，并极大缩短燃烧室，已成为高马赫数飞行的潜在方案和研究热点，但目前诸多方案无法实现双模态和宽工作范围。本文提出一种新概念可变边界燃烧技术，基于可变楔角强化耦合驻定爆震 ，通过对非设计点工况强化激波的生成和模态转化时激波衰减规律研究、可变边界扰动对斜爆震波火焰面的迁移微观结构变化、对激波诱爆的临界条件与稳定机制、激波耦合燃烧波的波阵面结构与反应诱导区的关系开展系列研究，为开拓激波诱燃方案和新概念空天组合动力提供必要的基础理论依据。本项目拟解决的关键技术包括可变边界扰动对火焰波阵面的迁移结构稳定极限影响，可变边界扰动对爆震波火焰面速度分布的影响，位移流对湍流燃烧压力梯度形成的涡流大小的影响，可变边界扰动对反应诱燃区的影响等基础机理。

爆震燃烧作为一种高效热循环效率的燃烧形式，由其发展而得的激波诱燃冲压推进技术已然将吸气式发动机推入了研究的高峰，为高超声速推进技术提供了革命性的理论设计概念。本项目以斜爆震的理论及高超声速燃烧为基础，对斜爆震在楔面上的形成结构以及稳定性和燃烧特性进行了基础研究。完成了数值求解斜爆震波的基础运算模块。开展了扰动边界下斜爆震波稳定机理的研究，详细的探究燃料当量比对斜爆震波诱导区结构和参数特性的影响，同时提出有效的诱导区长度理论预测方法。开展了燃料混气含N2对斜爆震波形成和稳定影响研究，并探究了斜爆震中的二次燃烧现象，给出二次燃烧出现的两端临界值。设计了双角斜坡楔形结构，数值验证了两种双角斜坡上斜爆震波形成的设想概念，进一步研究了双角斜坡楔形上斜爆震的结构和燃烧特性，提出了近CJ斜爆震波的形成机理和获得方法。初步探索了光滑过渡楔形上斜爆震波的燃烧效率和参数特性。结果表明，斜坡角在近CJ角度下，斜激波诱导斜爆震波具有稳定的结构，且在边界扰动下具有稳定性，虽结构未有明显变化，但扰动后爆震波下游区域的稳定性明显下降。较高的初始楔面倾角会缩短诱导区长度，对于提高激波诱燃冲压发动机性能有着至关重要的作用。