超声速H2/Air湍流扩散燃烧RANS数值模拟

RANS Simulation of Turbulent Non-Premixed H2/Air Combustion in a Scramjet

关键词:  超声速湍流燃烧  数值模拟  火焰面模型

Key words:  Supersonic turbulent combustion  Numerical simulation  Flamelet model

摘要:

为了研究修正的火焰面反应进度变量燃烧模型在超声速湍流扩散燃烧问题中的适用性，对德国宇航中心(DLR)超声速燃烧室开展RANS数值模拟。基于OpenFoam软件平台中密度求解器分别对三维冷态场和燃烧场进行模拟分析。将网格自适应加密技术用于流场的计算；燃烧场计算中，通过分析不同压力下层流火焰面数据库，引入了反应进度变量源项的压力修正系数，压力修正系数[α]等于2.2。计算结果表明，冷态场中压力分布、波系分布、速度分布以及燃烧场中波系分布、速度分布、温度分布结果均与实验值符合较好。压力修正方法能够较好地解决超声速湍流扩散燃烧问题。湍流Schmidt数敏感性分析表明，湍流Schmidt数[Sct]对湍流火焰结构有较大影响，文中[Sct]等于0.7时能得到与实验值较为一致的分布。

Abstract:

Reynolds-averaged-Navier-Stokes (RANS) simulations of the scramjet of the German Aerospace Center (DLR) has been performed to investigate the validity of revised flamelet/progress variable turbulent combustion model. Both three dimensional non-reacting and reacting flows have been investigated using density based solver of open CFD software， OpenFoam. The adaptive mesh refinement technique was used in the present simulations. In the reacting flow， pressure correction coefficient for the source term of reaction progress variable was introduced by analyzing laminar flamelet thermo-chemistry table under different pressure. The value of the pressure correction coefficient is suggested to be 2.2. The numerical results for pressure， wave distribution and velocity in non-reacting flow as well as for wave distribution， velocity and temperature in reacting flow are in good agreement with experimental data. It shows that the revised chemistry model can be used to predict the supersonic turbulent non-premixed combustion. The sensitivity analysis shows that the turbulent Schmidt number has significant influences on the flame structure. When turbulent Schmidt number is set to 0.7， the results agree reasonably well with the experiments.