矩形隔离段内激波串结构及其影响因素分析

Analysis of shock waves structure and its influencing factors in rectangular isolator

隔离段是超燃冲压发动机的重要组成部分,主要作用是隔绝燃烧与进气道的相互干扰。隔离段中存在的复杂流动现象一直是人们研究和关注的重点。利用三维数值模拟方法对矩形隔离段激波串特性影响因素进行了研究,主要分析了不同来流马赫数、单侧和对称扩张角以及壁面凹腔等因素影响下的激波串特性。结果表明:在高来流马赫数条件下,隔离段内激波串长度变短,隔离段抗反压能力增强,总压损失增大;在单侧和对称扩张隔离段内的激波串结构存在差异,且隔离段后的流场总压损失与扩张形式无关;隔离段添加壁面凹腔后,在不同反压下会出现2种模态(亚临界凹腔模态和超临界凹腔模态),2种模态下隔离段内激波串结构及流场参数特性有所不同,超临界凹腔模态下隔离段抗反压能力下降,总压损失增大。本文的研究结果可为隔离段和燃烧室设计及试验提供参考。

The isolator is an important part of the scramjet engine, which mainly plays the role of isolating the interference between combustion and the intake duct. The complex flow phenomenon in the isolator has always been the focus of research and attention. In this paper, a three-dimensional numerical simulation method is used to study the influence factors of shock train characteristics of the rectangular isolator. The shock train characteristics under the influence of the factors such as different incoming Mach numbers, symmetry or single expansion angle, and wall cavity are analyzed. The results show that under the condition of high Mach number, the length of the shock train in the isolator becomes shorter, the anti-backpressure ability of the isolator is enhanced, and the total pressure loss increases;the shock train structures in the single expansion isolator and the symmetry expansion isolator are different, and the total pressure loss of the flow field after the isolator has nothing to do with the expansion form;after adding a wall cavity to the isolator, two different modes would appear according to the difference in the back pressure, namely the subcritical cavity mode and the supercritical cavity mode, and the shock train structure and flow field parameter characteristics in the isolator are different in the two modes. Under the supercritical cavity mode condition, the anti-backpressure ability of the isolator decreases, and the total pressure loss increases. The research results of this paper can provide reference for the design and test of the isolator and combustion chamber.