解离效应对超燃冲压发动机燃烧与传热的影响特性研究

Effects of Dissociation on Combustion and Heat Transfer of Scramjet

关键词:  超声速燃烧  理论模型  解离效应  当量比  发动机性能

Key words:  Supersonic combustion  Theoretical model  Dissociation effect  Equivalence ratio  Engine performance

摘要:

为了分析高温解离效应对超燃冲压发动机燃烧和传热的影响，在超声速流动与燃烧一维理论模型的基础上，提出了“解离效率”的概念，建立了一种对高温燃气解离吸热效应进行量化评估的方法和发动机流动理论分析模型。应用该模型对日本宇宙航空研究开发机构M12-02发动机模型进行了研究，定量分析了解离效应对飞行马赫数12条件下超声速燃烧流动与传热的影响特性。研究表明，高温解离效应使得发动机性能损失明显，损失程度与燃料当量比有关。燃料当量比0.5时，氢燃料发动机、乙烯燃料发动机推力和比冲下降6%左右，壁面总热量减少约4%。当量比增加至1.0时，燃烧室内流温度升高，解离效应显著增强，氢燃料发动机、乙烯燃料发动机推力和比冲的损失增至22%左右，壁面总热量下降约16%。

Abstract:

In order to analyze the effects of high temperature dissociations effect on combustion and heat transfer of scramjet， a concept of ‘dissociation efficiency’ is proposed based on one-dimensional reactive flow model of supersonic flow and combustion. A quantitative evaluation method to determine the dissociation endothermic effect of high temperature gas as well as an analytical model for reactive flow of scramjet is developed. The model is used to study the flow and heat transfer properties of M12-02 engine of JAXA. Quantitative results of the effects of high temperature dissociation effect on supersonic flow and heat transfer under flow conditions of Mach number 12 are obtained. The present results show that due to dissociation effect， the engine performance loss is obvious， which is related to the fuel equivalent ratio. When the fuel equivalent ratio is 0.5， the thrust and specific impulse of the hydrogen fuel engine and ethylene fuel engine reduce by about 6%， and the total wall heat decreases by about 4%. As the equivalence ratio increases to 1.0， the dissociation effect is significantly enhanced with flow temperature in the combustion chamber increasing. The thrust and specific impulse losses of hydrogen fuel engines and ethylene fuel engines increase to about 22%， and the total wall heat decreases by about 16%.