应用S-A模型的自由射流和冲击射流数值模拟

Computation of axisymmetric jet flow with Spalart-Allmaras turbulence model

关键词:  自由射流  冲击射流  有限体积法  SA湍流模型  数学仿真

Key words:  Free jet  Impinging jet  Finite volume method  S A model  Mathematical simulati

摘要:

为探索轴对称射流准确的数值模拟方法 ,根据可压缩的轴对称N S方程 ,利用二阶精度的有限体积法对轴对称的自由射流和垂直冲击射流进行数值模拟。结果表明采用Spalart Allmaras湍流模型 ,可很好描述射流流动。收缩喷嘴射流计算应从出口上游的内流开始 ,而不能在出口截面上给定声速条件。计算结果与实验吻合较好 ,所获得的喷嘴内外部流场的流动状况以及冲击射流参数分布 ,可用于优化喷嘴内部结构设计。

Abstract:

A computational study for axisymmetric jet flow with Spalart Allmaras turbulence model was carried out.The second order finite volume method,fine unstructured grids and non reflecting boundary condition were used in solving the compressible N S equations.The numerical results are in good agreement with experimental data.It is demonstrated that the Spalart Allmaras turbulence model is suitable for numerical simulation of the axisymmetric jet flow and the sufficiently fine unstructured grids are helpful in obtaining the flow field details.In addition,it is found that,for under expanded jet flow,computation should be started from the internal upstream of the nozzle exit and its exit boundary conditioned should not be prescribed as sonic profile in this case.It is useful in understanding nozzle internal and external flow field and impinging jet parameter distribution.It is also helpful for optimal design of nozzle internal structure.