马赫数10超燃冲压发动机燃烧室流动与传热变化特性分析

Analytical Study on Flow and Heat Transfer Characteristics of Mach 10 Scramjet Combustor

关键词:  超燃冲压发动机  理论模型  构型参数  燃烧室性能  壁面传热

Key words:  Scramjet  Theoretical model  Configuration parameters  Combustor performance  Wall heat transfer

摘要:

针对高马赫数超燃冲压发动机燃烧室流动与传热的变化特性，基于考虑燃料/空气混合与燃烧、壁面传热及高温燃气解离效应的一维流动与传热分析模型，定量分析了飞行Ma10工况下解离效应对发动机燃烧室内流参数和性能参数的影响程度。研究结果表明，高温解离对高马赫数燃烧室流动与传热的影响显著。氢燃料当量比0.7时，如果不考虑解离效应，燃烧室推力的计算结果偏高15.3%，壁面传热量偏高13.5%。基于此，本文通过考虑解离效应的理论分析模型研究了Ma10圆形截面燃烧室中氢燃料喷注位置、喷孔数目及燃烧室扩张角对燃烧室流场参数与壁面传热的影响特性，评估了燃烧室推力、壁面摩擦力以及壁面传热量的变化规律。研究表明，燃烧室扩张段的扩张角度对燃烧室性能影响较大，喷注位置和喷孔数目的影响比较小。扩张角从1°扩至2°，燃烧室推力增长124.0%，壁面摩擦力减小3.0%，壁面传热量减少7.0%。适当增大燃烧室扩张段的扩张角度可以提高燃烧室推力，同时降低壁面热流和壁面摩擦力。

Abstract:

For the study of flow and heat transfer characteristics in the combustor of the high-Mach-number scramjet， a one-dimensional flow and heat transfer analysis model， which integrates with the fuel/air mixing and combustion models， wall heat transfer model and high-temperature gas dissociation effect， is used to quantitatively analyze the dissociation influence on the flow and performance parameters of scramjet combustor under flight Mach 10 conditions. The analysis results show that the high temperature dissociation has a significant effect on the flow and heat transfer in scramjet combustor. Without dissociation effect calculated， as the hydrogen fuel equivalent ratio is 0.7， the thrust of the combustor is overestimated by about 15.3%， the total wall heat is overvalued by about 13.5%. Furthermore， the influence of configuration parameters such as the injection position， the number of injection holes and the angle of the expansion section of the combustor on the flow field and heat transfer are obtained by the theoretical analysis model considering dissociation effect for the Ma10 circular cross-section combustor. The variation laws of the thrust， wall friction and total wall heat of the combustor are also evaluated. The research shows that the expansion angle of the expansion section of the combustor has a significant effect on the combustor performance， while the changes of the injection position and the number of injection holes have little effect. With the expansion angle expanded from 1° to 2°， the thrust of the combustor increases by 124.0%， while the friction is decreased by 3.0% and the total wall heat is reduced by 7.0%. What’s more， appropriately increasing the expansion angle of combustor is beneficial to improving the thrust of the combustor， and decreasing the wall heat flux and wall friction.