一种农用气液两相喷头的设计与喷雾特性仿真

Design and simulation of an agricultural twin fluid nozzle

基于文丘里原理设计了一款农用气液两相喷头,并采用k-ε湍流模型,利用FLUENT和CFX求解器对喷头内部气流场进行了计算流体力学(CFD)仿真和试验验证。结果表明:喷头出口平面中心区域的气流速度达到亚音速和超音速,喷头出口的气流速度随着两相压力的增加而增加;当气相入口压力一定时,液相入口压力的增大可使喷头下方两侧气流朝喷头轴向集中,喷口中心区域气流速度的实测值与仿真值的相对偏差≤10%,仿真结果真实可靠。雾滴粒径测试结果表明:在0.05MPa的恒定水压下,雾滴粒径随着气压的增高而降低;在常用工作气压下,距喷头喷射距离1.6m处,粒径65μm以下的雾滴比例≥85%,雾滴体积中径(D50)<50μm。所设计的喷头雾化性能优异,可获得烟雾级雾滴,适用于在设施农业中进行整棚弥散性喷雾防治病虫害。

An agricultural twin fluid nozzle was designed based on the Venturi principle.FLUENT and CFX solvers were used to perform computational fluid dynamics(CFD)simulation and experimental verification on the airflow field inside the nozzle was done as well.Results showed that the air velocity at the nozzle outlet in center area of the nozzle outlet reached subsonic and supersonic speeds.With the increase of the two-phase pressure,the air velocity increased accordingly.When the air pressure was constant,the air flow would concentrate towards the axial direction with the increase of water pressure.The relative deviation between the measured value and simulated value was not more than 10%,indicating the simulation results were reliable.The results of droplet particle size measurement showed that the particle size range of the droplets decreased with the increase of the air pressure at a constant water pressure of 0.05 MPa.Under the common working pressure,the ratio of droplets below 65μm was not less than 85%at the distance of 1.6 m from the nozzle,and the volume median diameter(D 50)was less than 50μm.The twin fluid nozzle has an excellent atomization performance and can obtain droplets at smoke-level,which is suitable for diffused spray prevention of the pests and diseases in the entire greenhouse.