固体燃料超燃冲压发动机燃烧室中火焰稳定性数值研究

Numerical Investigation of Combustion Flammability Characteristics in Solid Fuel Scramjet Combustor

关键词:  固体燃料  超声速燃烧  冲压发动机  数值模拟  火焰稳定

Key words:  Solid fuel  Supersonic combustion  Ramjet  Numerical simulation  Flammability

摘要:

对固体燃料超燃冲压发动机燃烧室中PMMA的燃烧过程进行了基于动网格技术的非稳态数值仿真研究。基于超声速流中的耦合传热及质量注入建立了固体燃料燃烧的数值模型，研究了燃烧室构型和进气总温对固体燃料燃烧特性的影响。结果表明:和实验数据对比证实了本文数值模型的正确性。固体燃料超燃冲压发动机能够实现自点火建压和维持燃烧。在燃烧过程中，装药壁面燃速分布不均匀，凹腔逐渐变得扁平。随着主流流速增加和通道的扩大，凹腔的火焰稳定能力降低，直至熄火。初始凹腔较深、进气总温较高时有利于稳定火焰。当进气总温提升400K时，工作时间和燃料消耗量提高1.8倍。

Abstract:

The unsteady combustion of polymethylmethacrylate in solid fuel scramjet (SFSCRJ) combustor has been simulated numerically based on dynamic grid technology. A solid fuel combustion numerical model is established based on coupling of heat transfer and mass injection in supersonic flow. The effects of combustor shape and inlet total temperature on combustion characteristics of PMMA have been studied. The results show that the numerical model is proved to be effective by comparing with the measured values. Self-ignition pressurization and sustained combustion could be permitted in SFSCRJ combustor. During the process of combustion，the cavity becomes more and more narrow due to the uneven distribution of regression rate of fuel grain. The flame-holding capability reduces with the increase of the main flow velocity and the broaden of fuel port leading to the occurrence of flameout. A relatively deep cavity and relatively high inlet total temperature are helpful to sustain combustion. Both the working time and fuel consumption increase by 1.8 times when inlet total temperature increases by 400K.