超燃冲压发动机稳焰凹腔流场结构数值仿真

摘要

凹腔是一种常用的超燃冲压发动机火焰稳定装置,在超燃冲压发动机的设计过程中准确了解凹腔在不同飞行速度下的性能表现是十分重要的,由于凹腔内流体运动非常复杂掌握凹腔结构参数对凹腔内流场结构的影响是比较困难的.采用数值模拟对超声速凹腔流场结构进行了分析,着重研究了来流马赫数和凹腔长深比对凹腔剪切层增长特性的影响.研究表明,马赫数和凹腔长深比增大均导致凹腔剪切层增长率下降;马赫数对凹腔剪切层的影响和其对自由剪切层的影响类似,而长深比对凹腔剪切层的影响近似呈线性变化,且涡量厚度和可视厚度具有相似的变化特点;剪切层中心线的也同时受来流马赫数及凹腔长深比的影响.基于参数化计算结果,并借鉴自由剪切层增长率的建模思路和方法,成功建立了一个考虑了马赫数和长深比影响的超声速凹腔剪切层增长率预测模型,并用数值仿真的结果进行了模型的精确度验证.%The study on fluid properties in the cavity is important to the cavity flame stability,and it is difficult to establish a mathematical model for cavity share-layer.This paper analyses the fluid properties on the basic of calculation,and has mainly studied the influence of free-stream Mach number and length-depth ratio of cavity on the growth ratio of the cavity share-layer.The study shows that,the increase of free-stream Mach number and length-depth of cavity ratio can result in the decrease of the growth ratio of the share-layer,the influence of Mach number on the cavity share-layer is similar than on the free share-layer,the influence of the cavity length depth ratio on the growth ratio of the share-layer is nearly linear,the influence on the thickness of the vortices is similar to the thickness of the visual,and the length-depth ratio of cavity and Mach number also influence the centre line of share-layer.On the basic of calculation and the theory of free share-layer,we also built a predict model of the cavity share-layer growth ratio during this interval.