湍流方程扩散项离散对某径向叶轮流场计算的影响

在相对旋转坐标系下采用Harten，Lax and van Leer contact （HLLC） 格式离散对流项，自行开发了基于多块结构化网格的有限体积程序，实现了对叶轮机械内部流场的数值求解.分别对半开式径向叶轮、闭式后弯叶轮展开数值模拟，程序和商业软件计算得到的不同叶高处表面压力数据，其相对差异不超过1%，验证了算法的正确性.针对湍流方程的扩散项，分别使用完全离散和略去交叉导数项离散，通过对湍流黏度等值线、气动轴向力和力矩的比较表明:在网格正交性较好的情况下，略去交叉导数项的离散对计算结果的影响小于1%，显著地减小湍流方程离散的计算量. 

Influence of discretization of turbulence equation diffusion terms on flow field compuation of a radial impeller

By discretizing convective terms with the HLLC scheme in the relative rotating coordinate system, a finite volume analysis code based on multi-block structured grids was developed independently, in order to numerically solve the internal flow fields of turbomachineries. The flow simulations of an unshrouded radial impeller and a shrouded backswept impeller were carried out respectively. The surface pressure at various blade heights calculated by the code and commercial software agrees well with the relative difference smaller than 1%, which verifies the accuracy of the algorithm. As for the diffusion terms of turbulence equations, full discretization and part discretization by neglecting cross-derivative terms were used respectively. Through comparisons of turbulence viscosity contour, aerodynamic force and moment, it indicates that neglecting cross-derivative terms exerts little impact of less than 1% on the results when the grid orthogonality is not too bad, and thus the calculation quantity of turbulence equations can be reduced obviously.