圆转矩形喷管出口宽高比对射流雷诺剪应力的影响

采用热线风速仪，利用单斜丝，对宽高比W／H分别为1，4，8，12，16的5个圆转矩形收敛喷管和一个轴对称喷管的射流对称面上雷诺剪应力分布特性进行了实验研究。研究发现：在喷口下游不同截面上，射流宽、窄对称面上的雷诺剪应力沿径向均先缓慢增大，到达射流边界后迅速减小，射流边界逐渐沿径向外移。矩形喷管射流相比轴对称射流具有较强的旋流，雷诺剪应力较大，且随着宽高比增大，旋流强度增大，剪应力也逐渐提高，导致了射流与外流掺混增强。宽高比大于8以后，增大幅度逐渐减小。射流宽、窄对称面上的分布规律相同。

Reynolds shear stress characteristics of jets from circular-rectangular transition nozzles with different aspect ratios

The flow field and Reynolds shear stress characteristics of the jets from 5 circular- rectangular transition nozzles and one axisymmetric nozzle were investigated with inclined hot wire. The distributions of Reynolds shear stress in the wide and narrow symmetrical planes were measured on different downstream sections. Results show that in the radial direction, Reynolds shear stress increases slowly till the interface between jet and ambient gas, then decreases fast. Rectangular nozzles can induce stronger swirl flow than axisymmetric one and larger Reynolds shear stress, which increases with increasing aspect ratio. The Reynolds shear stress increment gradually decreases when the ratio exceeds 8. The distributions are the same in both wide and narrow symmetrical planes.