回流式自激振荡射流喷嘴内部流动特性分析

Numerical Simulation on Internal Flow Field of a Self-excited Oscillation Pulsed Jet Nozzle with Back-flow

为解决风琴管喷嘴、赫姆霍兹喷嘴和空化喷嘴较难适用于如钻井液输送等较低频率的场合的问题,基于附壁效应和回流反馈作用设计了一种新型的回流式自激振荡喷嘴,应用FLUENT软件对喷嘴的内部流动特性进行了数值模拟,揭示了射流自激脉动机理,得到了回流式自激振荡喷嘴脉动流场和频率特性。结果表明,基本型喷嘴出口速度脉动范围22~39 m/s,脉冲频率67.1 Hz,脉动稳定、频率较低;在出入口压差一定情况下,脉动频率受围压影响小,并随振荡腔长度增加而降低,变型设计容易,为新型自激振荡脉冲射流喷嘴的开发提供了参考。

In order to solve problem that the organ pipe nozzle,Helmholtz nozzle and cavitation nozzle are little suitable for the low frequency occasions such as drilling fluid transportation,a self-excited oscillation pulsed jet nozzle was developed based on the wall attachment effect and the back-flow feedback principle in this paper.The internal flow field of the nozzle was simulated with FLUENT software,the mechanism of self-excited pulsating jet was revealed,and the pulsating frequency characteristic of the self-excited oscillating nozzle was obtained.The simulation results show that the pulsating range of outlet velocity of the basic nozzle is 22-39 m/s and the pulsating frequency is 67.1 Hz.The pulsation is stable and the frequency is relatively low.Under a certain pressure difference,the pulsating frequency changes little with the confining pressure varying and decreases with the oscillating cavity length increasing.Variant design is easy for this kind of nozzle.These research results are helpful for the development of a new self-excited oscillating pulsed jet nozzle.