基于CFD的超声激振喷嘴雾化特性数值模拟研究

Numerical Simulation on Atomization Characteristics of Ultrasonic Vibration Nozzle Based on CFD

为了进一步提高超声激振喷嘴内部的湍流效果和提高喷嘴雾化效率,通过设置碰撞壁和振荡腔的结构对现有的超声喷嘴进行改进。利用哈特曼流体声波发生器原理,建立超声激振喷嘴雾化模型,利用CFD流体动力学仿真软件模拟喷嘴内部的流场,以喷距和碰撞壁角度两个主要参数对喷嘴出水口速度的影响。结果表明:通过分析喷嘴内部速度和压力流场云图发现喷嘴内部振荡腔和碰撞斜壁的设计会使喷嘴内部产生空化涡旋,空化涡旋内空化气泡的溃灭会增强流体的扰动,增强喷嘴内部流体的湍流的效果,增强喷嘴雾化的效果加强喷嘴内部流体的扰动效果,提高喷嘴的雾化效率;喷嘴射流速度随进口压力的增加表现出明显的增大趋势,射流速度对喷距的增加表现出明显的增加趋势,相比较之下碰撞壁角度对射流速度的影响不明显,经分析确定参数喷距L=1 mm,碰撞壁为60°时超声激振喷嘴雾化效果最好。

The flow field in the ultrasonic vibration nozzle of water jet was empirically approximated,mathematically modeled on the basis of Hartmann fluid acoustic generator principle,theoretically analyzed and numerically simulated with CFD software for design optimization of the ultrasonic vibration nozzle. The impact of the collisionwall angle,jetting distance and water inlet pressure on the jetting velocity was investigated. The simulated results show that the jetting velocity strongly depends on the inlet pressure and jetting distancebut weakly on the collisionwall angle. The ultrasonic vibration nozzle with the optimized structure,a jetting distance of 1. 0mm and a collision wall angle of 60°,has the highest water atomization efficiency. Possible mechanism responsible for the enhancement of atomizationefficiency was also tentatively discussed in a thought-provoking way.