基于Fluent外混式气动雾化喷嘴改进与仿真研究

Improvement and simulation of external mixing pneumatic atomizing nozzle based on Fluent

为了有效降低喷嘴气体能量的损耗,需要对气动雾化装置整体结构进行雾化速度和压力流场的仿真分析,通过改进局部设计来减少非必要的能量损失,以此来提高气体能量利用率,提升喷嘴雾化性能。为此,对外混式气动雾化装置的内外流场进行了数值研究。首先,对该气动雾化装置内部气相通道进行了数值模拟,找到了原设计中最大能量损失的原因;然后,根据流场的压力和速度分布规律,对壶体与喷嘴连接处的气相通道进行了局部结构改进,分析了装置改进前后内外流场的压力与速度变化情况;最后,通过模拟喷雾过程,对比了不同气压下原喷嘴和改进后的喷嘴内外流场的雾化特性,对喷嘴局部结构改进的合理性与改进后气动雾化装置性能的优越性进行了验证。研究结果表明:通过掏空雾化喷嘴主体和改变雾化喷嘴进气口形状的方式,可以有效改善气相通道的节流情况,减少气体能量的损失,缩短改进后的喷嘴气相通道内部高速气体路径,并且增加喷嘴气相出口附近的流场速度,最大增幅为11.49%;改进后的喷嘴雾化性能得到了提升,当气压在0.3 MPa附近时,其雾化效果最佳。

In order to effectively reduce the loss of gas energy of the nozzle,it is necessary to carry out the simulation analysis of the atomization speed and pressure flow field of the overall structure of the pneumatic atomization device,and reduce unnecessary energy loss by improving the local design,so as to improve the utilization rate of gas energy and improve the nozzle atomization performance.Therefore,a numerical study of the internal and external flow fields of the externally-mixed pneumatic atomization device was carried out.Firstly,numerical simulations of the internal gas-phase channel of the device were carried out,and the reasons of the maximum energy loss in the original design were found.Then,according to the pressure and velocity distribution of the flow field,the local structure of the gas-phase channel at the connection between the pot and the nozzle was optimized,and the pressure and velocity changes of the internal and external flow field before and after the optimization of the device were analyzed.Finally,the atomization characteristics of the internal and external flow fields of the original nozzle and the optimized nozzle were compared by simulating the spraying process at different air pressures,and the rationality of the nozzle local structure improvement and the superiority of the performance of the improved pneumatic atomization device were verified.The research results show that,hollowing out the atomizing nozzle body and changing the shape of the atomizing nozzle inlet can effectively improve the throttling of the gas-phase channel and reduce gas energy loss.The improved nozzle gas phase channel inside the high-speed gas path is shortened,and the flow field velocity near the nozzle gas-phase outlet increase,the maximum increase is 11.49%.The improved nozzle atomization performance is improved.When the air pressure near 0.3 MPa,the atomization effect is the best.