局部进气条件下空气涡轮火箭发动机掺混燃烧研究

Investigation on Turbulent Mixing and Combustion for Air-Turbo-Rocket Engine with Turbine Partial Admission

关键词:  空气涡轮火箭发动机  涡轮局部进气⁺  波瓣混流器  化学反应机理 

Key words:  Air-turbo-rocket engine  Turbine partial admission⁺  Lobed mixer  Chemical reaction mechanism

摘要:

为揭示空气涡轮火箭发动机燃烧室中富燃燃气与空气在涡轮局部进气条件下的混合增强机制和燃烧反应机理,对富燃燃气与空气的湍流混合及燃烧过程进行了数值模拟,并结合试验结果定量分析了两类燃烧组织方案的掺混和燃烧效率。研究结果表明:涡轮局部进气条件下波瓣混流器强化掺混的主导因素是大尺度流向涡的对流型混合,涡轮局部进气对涡系的初始空间分布及涡量强度具有显著影响,其对下游掺混质量的影响与波瓣型面相关；肼分解燃气与空气的燃烧是一种分支链锁反应,其主要反应历程是氢气的氧化反应和氨气的分解,热混合效率可作为掺混燃烧效率预测的重要参考量。 

Abstract:

In order to reveal turbulent mixing enhancement and chemical reaction mechanisms of the fuel-rich gas and airflow under turbine partial admission conditions in the combustion chamber of air-turbo-rocket engine, numerical simulations on turbulent mixing and combustion of the fuel-rich gas and airflow were carried out. A quantitative analysis was also conducted to study turbulent mixing and combustion efficiency of two kinds of mixing scheme by taking advantage of experimental results. Analysis results show that the convective mixing and streamwise vortices induced by a spanwise array of large scale secondary flows play dominant role in the introduction of lobed mixers to augment mixing of the bypass and core flows with a partial admission turbine. Partial admission flow conditions have significant effect on three dimensional distribution and the vorticity of initial vortices. Whether partial admission enhances turbulent mixing quality downstream of the lobe trailing edge or not rests with the lobed configuration. Furthermore, results indicate that hydrogen oxidation and ammonia free radical decomposition which involve a branched chain process are the main chemical reactions for fuel-rich hydrazinolysis gas. Thermal mixing efficiency is valuable reference quantity to estimate the turbulent combustion efficiency.