基于火焰面模型的超声速湍流燃烧数值模拟研究

Numerical Simulation of Supersonic Turbulent Combustion Flows Based on Flamelet Model

关键词:  层流火焰面模型  超声速湍流燃烧  湍流模型  数值模拟 

Key words:  Laminar flamelet model  Supersonic turbulent combustion  Turbulence model  Numerical simulation

摘要:

在非结构混合网格有限体积框架下,将RANS方程和层流火焰面模型相结合,开展超声速湍流燃烧流动数值模拟研究,时间和空间离散分别采用LU-SGS格式和HLLC格式。用SST k-ω模型模拟湍流,FlameMaster 3.9生成火焰面数据库,并采用β-PDF和δ-PDF分布来考察湍流和化学反应的相互作用。采用该数值方法,对DLR氢燃料超燃燃烧室和北航乙烯燃料气动斜坡超燃燃烧室开展了数值模拟研究,并将数值计算结果与实验数据进行对比,二者符合较好。研究结果表明:在主流中心支板顺流喷射超燃燃烧室内,燃烧主要发生在支板后的燃料/空气混合层内,并且火焰核心落在恰当混合物分数Zst附近区域。 

Abstract:

A solver based on the combination of Reynolds-Averaged Navier-Stokes (RANS) equations and laminar flamelet model is designed to simulate supersonic turbulent combustion within the finite volume framework on a hybrid unstructured polyhedral-cell mesh system. The implicit Lower-Upper Symmetric Gauss-Seidel (LU-SGS) algorithm is used as the time evolution method, while the convective fluxes are computed with the Harten-Lax-van Leer-Contact (HLLC) scheme. Menter''s shear stress transport (SST) k-ω turbulence model is implemented to model the turbulence. The laminar flamelet model is used as the combustion model and the flamelet table is constructed by the FlameMaster 3.9code. The interaction between turbulence and chemistry is accounted for by using the assumed β- and δ-PDF models. The solver is used to simulate the supersonic combustion flows in the DLR (German Aerospace Center) hydrogen fueled scramjet combustor and the ethylene (C₂H₄) fueled aeroramp injector/gas-portfire (ARI/G-P) Scramjet combustor at Beihang University (BUAA). The numerical results agree well with those of the experiments. It is concluded that combustion takes place in the wake of the fuel jets downstream the strut for a typically center equipped parallel injection strut Scramjet combustor, with the flame core settled in the vicinity region of the stoichiometric Zst. 