湍流模型在复杂流场数值模拟中的应用

采用4种湍流模型:代数Baldwin Lomax(B-L)模型、半方程Johnson King(J-K)模型的两个版本(J-K90A和J K92)以及两方程k-g模型,分别数值模拟了导弹超音速流动、NASATND-712标模和民机翼身组合体(两区C-O网格)跨音速流动.采用中心有限体积和多步Runge-Kutta方法数值积分三维可压缩雷诺平均Navier-Stokes(N-S)方程组.k-g湍流模型方程的求解采用类似于N-S方程组的方法进行.所有湍流模型均能很好地模拟附体及小分离流动;对于大攻角、分离剧烈的导弹流动,k-g和J-K92模型与实验吻合更好;B-L模型在模拟民机跨音速流动时,它所捕捉的激波位置较其余3种模型靠后.利用多块网格模拟民机翼身组合体流场时,k-g模型的模拟能力强于其余3种模型.

Applications of Turbulence Models in Simulation of Complex Flows

Four turbulence models:algebraic Baldwin-Lomax model with Degani-Schiff modification, two versions of Johnson-King model (J-K90A and J-K92) and two-equation k-g model, are described and evaluated for missile supersonic flow, NASA TN D-712 standard model and the civil airplane wing-body configuration (two-block C-O mesh) transonic flows. The 3-D compressible Reynolds averaged Navier-Stokes (RANS) equations are integrated numerically by central-difference with artificial viscosity scheme, finite volume formulation and explicit multi-step Runge-Kutta algorithm. The turbulence equations of k-g model are explicitly solved in the same way as the RANS. Results show that all models can perform well for attached and mildly separated flows. For large angle-of-attack separated flow over the missile, k-g and J-K92 models match the experimental results much better than those with B-L and J-K90A models. According to the B-L model with some modification, the shock location logs behind those with the other three models for the civil airplane geometry. Model k-g, because of its advantages such as without using normal-to-wall distance, simple source terms and straightforward boundary conditions, performs best in the four models for complex configuration with multi-block mesh system or multi-wall interference. B-L and J-K models, despite of cheapness and robustness, both base on empirical Prandtl mixing-length hypothesis and need to calculate the distance normal to the wall, undoubtedly limiting the application scope of these models for multi-block mesh system and complex geometry.