液体张力对风场中雾滴特性影响的试验研究

Experimental Research on the Effect of Liquid Tension on the Characteristics of Droplets in Wind Field

为研究液体表面张力对远射程风送式喷雾机外部流场中雾滴特性与分布的影响,使用ANSYS ICEM软件建立了远射程风送式喷雾机出风口及外部流场的三维模型,采用CFD数值模拟探究液体表面张力分别为60.3、54.5、44.6、38.4、31.8mN/m时流场中雾滴粒径、密度、速度和沉积分布情况。结果表明:喷雾压力为1.8MPa时,各采样面上雾滴体积中值粒径随着喷雾距离的增加而变小,降低液体表面张力可以细化流场中雾滴粒径。不同液体表面张力下,喷筒出风口轴心范围0~1m区间内雾滴密度在流场中是最大的;当液体表面张力从60.3mN/m下降至31.8mN/m时,雾滴密度>0.07kg/m^3所占面积沿喷筒出口轴线方向逐渐增加。雾滴平均速度随喷雾距离的增加而减小,液体表面张力对距离喷筒出口1~6m区域内雾滴平均速度影响最大,表现在液体表面张力越大雾滴平均速度越小。相同采样点上,雾滴沉积量随液体表面张力降低而减少。将雾滴沉积量的数值试验结果与田间试验结果进行χ~2检验,证明了所采用的模型仿真结果可信。

In order to study the effect of surface tension of liquid on the characteristics and distribution of droplets in the external flow field of the long-range air-blast sprayer,a three-dimensional model of the outlet and external flow field of the long-range air-blast sprayer was established by using ANSYS ICEM software,Using CFD numerical simulation to explore the droplet’s diameter,density,velocity and deposition distribution in the flow field,when the surface tension of liquid was 60.3,54.5,44.6,38.4,31.8 mN/m.The results demonstrated that when the spray pressure is 1.8 MPa,the volume median diameter on each sampling surface becomes smaller with the increasing distance of the spray;decreasing the surface tension of liquid is able to refine the droplet’s diameter in the flow field.Despite the surface tension of liquid,the droplet density reaches the highest when the outlet’s axis range falls between 0 to 1 meters.When the surface tension of the liquid drops from 60.3 mN/m to 31.8 mN/m,the area of the droplet density which is greater than 0.07 kg/m^3 gradually increases along with the axis of the spray’s outlet.The average velocity of the droplets decreases as the increase of the spraying distance.The surface tension of the liquid has the greatest influence on the average velocity of the droplets in the region of 1 to 6 meters from the spray’s outlet,illustrated by the negative correlation between the surface tension of the liquid and the average velocity of the droplets.At the same sampling point,the deposition of the droplets decreases when the surface tension of the liquid becomes smaller.The numerical test results of the deposition of the droplets and the field test results were tested by theχ~2-test,the model simulation results used in this paper were credible.