液滴发生器工作过程的动力学特性

Dynamic Characteristics of Droplet Generator Operation Process

关键词:  液滴发生器  压力分布特性  分布参数模型  动态特性

Key words:  Droplet generator  Pressure distribution characteristics  Distribution parameter model  Dynamic characteristics

摘要:

为了研究喷孔位置对液滴发生器均匀液滴生成稳定性的影响，发展了液滴发生器工作过程的动力学特性计算模型，给出了基于声学理论的集液腔压力响应空间分布函数。考虑到部分小孔径、大长径比直流喷嘴的工作特点，在传统集中参数模型的基础上，建立了分布参数模型。随后，分析了Rayleigh模式下射流表面波色散关系的影响因素。结果表明，在特定的激励频率区间内，喷注面会产生近似圆环形状的波节结构，并随着频率的改变沿径向移动，因此液滴发生器的喷孔位置设计应当考虑喷注面的压力分布特性。与集中参数模型类似，喷嘴分布参数模型计算出的脉动流量也是随着激励频率的提高而减小，但滞后相位角保持约90°不变。分布参数与集中参数模型的适用界限要根据射流表面波的色散关系以及喷嘴长径比共同确定。

Abstract:

In order to study the effects of injection position on mono-dispersed droplet generation stability，a dynamic model for droplet generator operation process was developed. Pressure response distribution function in the fluid cavity was proposed according to acoustic theory. Considering the characteristics of jet injector with small diameter and large length to diameter ratio，the distribution parameter model was presented based on the conventional lumped parameter model. Then，the factors influencing on the dispersion relation of jet surface wave in Rayleigh regime were analyzed. Results show that a near-circular nodal line is generated on the injection plate in a certain range of excitation frequency，and it moves along the radial direction while oscillation frequency changes. So characteristics of pressure distribution on the injection plate should be taken into consideration during injector position design of droplet generator. Flow oscillation calculated by the distribution parameter model decreases with the increase of excitation frequency，which is similar to the lumped parameter model results. But the lagging phase angle keeps about 90°. The applicable boundaries between two injector models are jointly determinated by the length to diameter ratio of jet injector as well as the dispersion relation of surface wave.