台阶后横喷氢气超音速燃烧流场数值模拟研究

A NUMERICAL SIMULATION ON SUPERSONIC FLOW OVER A REARWARD FACING STEP WITH TRANSVERSE HYDROGEN INJECTION

关键词:  超音速冲压喷气发动机  超音速燃烧  数值模拟

Key words:  Supersonic combustion ramjet engine  Supersonic combustion  Numerical simulation

摘要:

采用ＭｃＣｏｒｍａｃｋ格式、代数涡粘性湍流模型及有限速率化学动力学模型，用数值模拟方法研究了台阶后横喷氢气二元燃烧流场。数值计算结果表明：台阶的作用不仅能扩大火焰稳定性，而且增加氢射流对主流的穿透深度，提高燃烧效率；当进口气流Ｍ数越高，进口温度越高，油气当量比越接近于恰当比，壁面温度对流场的影响越大。还提出了在超音速气流中，横喷氢自动着火时滞的火焰稳定机理新观点，由此可更准确地预估自动着火点的位置及火焰稳定性。

Abstract:

A detailed theoretical examination of flow over a rearward facing step is presented,using a two-step global hydrogen-air combustion model, Baldwin-Lomax’s algebraic eddy-viscositymodel and MacComack explicit time-split method. The results show that rearward facing step is quiteuseful for autoignition, flame stabilization and combustion efficiency, and that the flowfield is affectedby the wall tempeture boundary condition. A new concept on autoignition and stabilization ofhydrogen in supersonic flow is provide in the paper by which the position of autoignition point andstabilization can be assessed.