双工况氢氧发动机燃烧与传热数值分析

Numerical analysis of combustion and heat transfer in dual-operation LOX/hydrogen engine

关键词:  氢氧发动机  喷嘴  燃烧效率  传热  数值仿真

Key words:  Hydrogen oxygen engine  Injector  Combustion efficiency  Heat transfer  Numerical simulation

摘要:

应用三维湍流N S方程以及颗粒轨道模型描述双工况氢氧发动机内部喷雾两相燃烧流动过程。两相之间的质量、能量交换由液滴蒸发模型计算,气相化学反应速率由Arrhenius公式计算。通过耦合求解气液两相的模型方程,对发动机转工况前后的三维流场进行了数值计算,并耦合计算了燃气与壁面之间的传热以确定壁面的温度和热流分布。另外还对分别采用同轴离心式喷嘴和直流式喷嘴得到的燃烧流场与燃烧效率进行了比较。计算结果表明转工况前的壁面温度与热流都比转工况后大。离心式喷嘴的雾化混合效果与燃烧效率都比直流式喷嘴好。

Abstract:

Three-dimensional N-S equations and two-phase flow model, in which the liquid oxygen spray as discrete particles was considered, were employed to describe the turbulent combustion processes in the dual-operation LOX/hydrogen engine. The mass and energy transfer between the two phases were calculated by the droplet evaporation model, and the Arrehnius model was used to obtain the gas chemical reaction rate. The details of 3D flow field, the distributions of temperature and heat flux in the wall were obtained by solving the equations and calculating the coupling heat transfer between the burning gas and chamber wall. The flow field and combustion efficiency of swirl coaxial injector and shear coaxial injector were compared. The results show that the temperature and heat flux of oxygen-rich operation are higher than that of the fuel-rich operation, and the mixture and efficiency of swirl coaxial injector are better than that of the shear coaxial injector.