非定常IV型激波－激波干扰数值模拟研究

对IV型激波-激波干扰非定常流动进行了数值模拟，采用有限体积法，结合空间半隐的二阶OC-TVD格式与时间二阶显式Runge-Kutta法求解三维全N-S方程，并且使用了Baldwin-Lomax代数湍流模型．得到了周期性流场变化结果，其中包括周期变化的双涡结构．壁面压强峰值的大小和位置均呈周期性振动，壁面压力系数和Stanton数的时均分布与定常实验结果符合得较好．并从一周期内流场结构的扰动传播出发，分析了结构变化的相位，说明了IV型激波一激波干扰内在的非定常性机理与影响因素。

NUMERICAL INVESTIGATION OF AN UNSTEADY TYPE IV SHOCK-SHOCK INTERACTION

Self-sustained unsteady turbulent flow resulting from a IV typed shock-shock interaction is simulated numerically. Full N-S equations implemented with the algebraic Baldwin-Lomax model are solved by using finite volume method, second-order Harten-TVD spatial scheme and second-order Runge-Kutta method. Regular oscillatoins and a periodic structure of dual eddies are observed, which do not exist in steady cases. The peak pressure also oscillates regularly in its value and position, but their variation are very small. Time-averaged wall pressure coefficient and Stanton number distributions appear in good agreement with steady experimental results. From variations of three representative lines in the flow field, the inherent unsteady mechanism and influence factors are then analyzed by studying disturbances propagating in one cycle, and the phases of the structure variation. The disturbances propagate through subsonic areas, shocks and shear layers. Because of different structures having different phases, the disturbances finally result a regular periodic flow field. It shows that the phase difference between two shear layers near the wall, and the length difference between shear layers abuting against the supersonic jet are two facts that influence the flow field significantly.