不同雾化方式喷雾场的数值分析与试验验证

Numerical analysis and test verification of spray field of different atomization nozzle modes

为了研究植保雾化喷头的雾化效果,基于CFD中拉格朗日粒子跟踪气液两相流模型,分别结合压力雾化和空气雾化模型对不同风速下的雾滴粒径、运动速度、质量浓度分布规律进行了对比计算.计算结果表明:压力雾化模型中,雾滴粒径小于100μm的占比小于2%,粒径175μm的细雾滴占比约为25%,近喷雾口处雾滴速度更高,约是空气雾化模型的5倍;雾滴质量浓度分布更均匀;当风速达到4 m/s时,细雾滴分布比例增加,雾滴会出现二次破碎.空气雾化模型,中等雾滴粒径分布在400~600μm,占比约为20%,雾滴速度衰减慢,喷雾口附近雾滴不易逆风运动;雾滴沉积范围小,喷幅较窄,大部分雾滴沉降在以喷头为中心的1.5 m范围内.此外,完成了低速风洞试验,收集雾滴沉积并进行卡方检验,结果表明2个雾化模型对于喷雾场中液滴沉积值均可信,但压力雾化模型计算值与试验值偏离度较小.

To study the atomization effect of plant protection spray nozzle,based on the Lagrangian particle tracking gas-liquid two-phase flow model in CFD,and combined with the Pressure-swirl-atomize,and the Air-blast atomizer,respectively,the distribution of droplet size,movement velocity and mass concentration distribution under different wind speeds were calculated and compared.The calculation results show that in the pressure atomization model,the particle size of fog drops less than 100μm accounts for less than 2%,and the particle size of fine fog drops 175μm accounts for about 25%.The droplet velocity near the spray nozzle is higher,which is about 5 times that of the air atomization model.The droplet mass concentration distribution is more uniform.When the wind speed reaches 4 m/s,the distribution ratio of fine fog drops increases,and secondary fragmentation occurs,the droplets will burst again.In the air atomization model,the particle size of medium droplets is 400-600μm,and the proportion accounts for about 20%.The droplet velocity decays slowly,and the droplet is not easy to move against wind near the spray nozzle.The deposition range of fog droplets is small and the spray amplitude is narrow.Most of the fog droplets settle in the 1.5 m range centered on the nozzle.Furthermore,the low-speed wind tunnel test is completed to collect the droplet deposition and the chi-square test are both carried out.The test results show that the two atomization models are both reliable for droplet deposition in the spray field,but the deviation between the calculated value of the Pressure-swirl-atomize and the test value is smaller.