收缩喷嘴内部流道型线对射流流场的影响

为研究收缩喷嘴内部流道形成对射流流场的气体动特性参数的影响，根据可压缩流体轴对称N-S方程，采用非结构网格和二阶精度的有限体积法，对不同内部流道形线的喷嘴自由射流进行数值模拟。亚声速射流采用RNGk-ε湍流模型，超声速射流采用S-A湍流模型，计算结果与实验较吻合。在亚声速流动中，收缩喷嘴的收缩角大小会影响其对射流的阻滞效果，内部流道形线设计为维多辛斯基曲线可以获得更好的流场动特性参数，有利于提高喷嘴的工作效率。在超声速流动中，喷嘴流道型线对出口膨胀波的角度与强弱影响较大，要根据射流的有效作用区域选择合适的喷嘴，才能使能量的损失最小。若要获得较佳的外部流场参数，优化喷嘴内部流道设计十分重要。

Effect of Nozzle Exit Shape on Aerodynamic Characteristic of Free Jet

Results of a numerical study of the effect of nozzle exit shape on round turbulent free jet are presented. Three nozzle types with the same exit area were used: two sharp-edged nczzles and a smoothly contoured nozzle. Two flow configurations: a subsonic jet case and a supersonic jet case are computed using different turbulent model (RNG k-ε model and S-A m odd) .The result indicates that the nozzle interior shape has important effect on aerodynamic characteristic of free jet. Using seeond-order-accurate finite-volume schemes, sufficiently fine unstructured grid and non-reflecting boundary condition ensures numerical credibihty of the solutions. The results demonstrate favorable agreement with experimental data.