超声速后台阶流动/射流相互作用的数值模拟

Numerical Simulation of Supersonic Flow/Jet Interaction at the Double Backward-Facing Step

采用高精度格式求解二维Navier-Stokes方程研究超声速射流与同向超声速后台阶流动相互作用的流场基本结构及规律,分别应用5阶WENO格式、6阶中心差分格式离散对流项和黏性项,时间推进采用3阶Runge-Kutta格式,并应用消息传递接口(message passing interface, MPI)非阻塞式通信实现并行化.分别研究了超声速后台阶流动、超声速射流的基本结构特征,以此讨论和分析超声速后台阶流动/射流相互作用的特征,以及不同来流条件对波系结构、涡结构、剪切层、膨胀扇等的影响,尤其是来流剪切层和射流剪切层的相互作用,形成复杂的波系结构及相互干扰的流动现象.

In order to study the interaction between jet and supersonic flow,high accurate scheme was adopted to solve 2D Navier-Stokes equations studying the basic structure and law of interactions between jet and supersonic flow.The 5^th order WENO scheme and the 6^th order central difference scheme were used to discretize the convection term and viscous term respectively.Furthermore,the time marching scheme was adopted in the 3^rd order Runge-Kutta scheme,and the parallel computation was performed by using MPI non-blocking communication.Double backwards-facing step was presented in this paper.Supersonic flow(no jet),basic structure of jet and supersonic flow/jet interaction under different pressure ratios were studied respectively.It is found that jet structures with height above 20 km are highly under expanded jet.The interaction between supersonic slow and jet has obvious heating the wall of steps,which is about 400 K higher than that of the only flow.The complicated supersonic flow/jet interaction makes the flow field instability in advance,which forms the complex wave structure,shock wave/Kelvin-Helmholtz vortex interaction and other flow physics phenomenons.