空气节流对超燃燃烧室流场结构与燃料混合影响的数值研究

Numerical Study on Air Throttling Influence of Flow Structure and Fuel-Air Mixing in Scramjet Combustor

实现高速气流的点火和稳定燃烧是超燃冲压发动机燃烧室设计面临的主要问题,空气节流通过在流场中产生激波串,减小主流气体的马赫数,提高当地的静温和静压,辅助发动机实现起动点火和稳定燃烧。为了研究空气节流的详细机理,通过求解三维N-S方程的方法研究了节流流量、节流位置对节流效果的影响,同时对比了有无节流存在对超燃冲压发动机燃烧室流场结构和掺混特性的影响,分析了节流促进燃料高效混合的机理。结果表明:在燃烧室入口马赫数2、静温517.7K、静压101342.2Pa的条件下,20%入口空气流量的节流流量是最合适的节流流量,本文研究的实例中最佳节流位置位于距燃烧室入口623mm处,同时证实了节流有效地促进了燃料的混合,提高了混合效率。

Achieving fuel ignition and steady combustion in a high-speed environment is a serious problem in designing scramjet combustor. Air throttling produces a proper shock train to reduce the local flow velocity and increases the pressure and temperature facilitating ignition and flame stabilization. In order to investigate the principle of air throttling, the location and flux of air throttling were studied by solving three- dimensional N-S equations. The effects of air throttling on the flow structure and mixing characteristics were studied while the mechanism of air throttling for increasing fuel-air mixing was also analyzed. CFD results show that under the inflow air condition of Ma =2.0, Te =517.7K,po = 101342.2Pa,20% mass flux of in- flow air is the best flux of air throttling, the best location of air throttling for the case studied is 623mm from the combustor entranee and air throttling promotes fuel-air mixing effectively.