冲压发动机燃烧室燃料喷射的简化计算方法研究

A simplified method to analyze injecting phenomena and its application to ramjet combustion chamber

为了采用二维/轴对称模型来研究喷射的三维问题,拓展该模型的适用范围,从而缩短数值模拟的周期,提出了一种针对流动通道内燃料喷射作用的简化模型,即采用源项加质来近似代替喷射的质量添加。为验证这种简化方法的可行性,进行了二维模型源项加质模拟垂直喷射的对比性计算,并且和三维模型计算结果及文献中的实验结果进行了对照,验证了此种处理方法的可靠性。运用以上简化模型,对某冲压发动机进气道及燃烧室内通道处的流场,采用五组元单步反应模型进行了数值模拟,得到了各主要气动参数及组分质量分数的分布。同时,研究了燃料喷射质量流量变化对于发动机工作状态的影响并探讨了亚燃冲压发动机进气道和燃烧室匹配方面的问题。通过以上的计算,表明采用源项加质处理,二维及轴对称模型,具有较好的时效性及足够的计算精度,适合在型面设计阶段进行使用,并容易在工程应用中实现,是一种值得推荐的简化处理方法。

In order to analyze the three-dimensional injection phenomena with two-dimensional and axial-symmetry model, i.e., to enlarge the scope of two models, a simplified method to analyze injecting process is introduced in the calculation process. With the special disposal towards the source term of the governing equations, the influence of mass addition in the injection process can be approximately estimated. Testifying calculation was carded out and proved the robnstness and feasibility of this method. The flow field in a sketch ramjet engine parts was simulated with the adoption of the above injecting simplified method and 5-species, single step reaction model, obtaining the major aerodynamic parameters and components distribution of the channel. Meanwhile, the influence of fuel equivalence ratio to the performance of the engine and some issues about the coupled analysis of the inlet-engine combination were investigated. The profoundness and robnstness of the simplified method is highlighted with the presentation of the above work and it is ready to be applied to the engineering field in terms of calculation precision and simpleness.