用离散涡方法模拟喷嘴出口射流流场的数值模型

根据流体力学原理，用离散涡方法建立了在复平面上模拟喷嘴出口流场的一套完整模型。在此基础上，用ＦＯＲＴＲＡＮ语言编写了计算机程序，模拟了喷嘴出口流场的速度分布，利用涡元矢量图对计算结果进行了分析，得出了射流在喷嘴出口分离流动及流场中旋涡形成及发展的规律。射流在有锐缘的地方会发生流动分离，形成的剪切边界层逐渐卷起，形成旋涡结构。在喷嘴出口与哨嘴出口处形成的旋涡结构，在势流流场和其它涡元的作用下逐渐向下游运动，并向两边扩散。由于粘性扩散及计算误差的影响，在远喷距处会出现涡旋结构变形

NUMERICAL MODEL FOR SIMULATING FLOW FIELD OF NOZZLE EXIT BY USING DESECRATE VORTEX METHOD

On the basis of fluid mechanics, a comprehensive model for simulating flow field at nozzle exit is developed by using desecrate vortex method. Based on that, a software is made in FORTRAN, by which the velocity distribution in flow field of nozzle exit can be simulated. The result of simulation is analyzed via vector figures of vortex elements, and the principles of jet separating flow and vortices forming and developing at nozzle exit are obtained. The flow can be separated at the acute edges, and the shearing boundary layer rolls up and gradually form vortex. Vortices of nozzle exit and whistle exit move gradually towards the downstream and spread outside under the action of potential flow field and other vortices. The shape of vortex changed in the downstream because of the viscous dissipation and calculation error.