基于计算流体动力学的风送式喷雾机风送系统流场模拟及结构优化

Field simulation and structure optimization of the air conveying system in air assisted sprayer based on computer fluid dynamics

为缩短研发周期,减少成本,通过计算流体动力学(computer fluid dynamics,CFD)技术对风送式喷雾机的风送系统进行设计和优化,从最大限度地减小气流能量的损失和涡流、提高流场分布均匀性的原则出发,设计了最佳的风箱结构和具体参数。为实现根据树冠形状调整风送系统高度和倾角以适应不同生长时期不同类型的果园,通过CFD模拟计算和试验,探究了风送式喷雾机的气流速度和安装角度对气流速度场的影响规律,并模拟分析了喷雾机流场分布规律。在获取了风送距离与风送速度的关系(随着风送距离的增加,风速逐渐减小,减小的幅度也逐渐减小)后,建立了喷雾高度与喷头倾角的线性关系模型。结果显示:当喷头倾角大于85°或小于40°时,喷头倾角变化对于气流场的改变影响不大;当喷头倾角为40°～85°时,随着喷头倾角的增加,喷雾高度也相应地增加。本研究为实现仿形喷雾的自动化提供了理论依据。

To shorten research and development cycle and reduce cost,an air conveying system in the air assisted sprayer was designed and optimized by computer fluid dynamics(CFD)technology.Based on the principle of minimizing the energy loss and vortex of airflow and maximizing the uniformity of flow distribution,we determined the optimal structure and specific parameters of the bellows.In addition,to adapt to different growth periods and different types of orchards by adjusting the height and inclination of the system according to the canopy shape,we explored the influence of air velocity and installation angle on air-flow field using CFD simulation calculation and test,and simulated the distribution of flow field in the sprayer.Then we established the linear model between spray height and nozzle inclination after obtaining the relationship between airflow distance and airflow velocity(as the wind transmission distance increased,the wind speed gradually decreased,and the decreasing amplitude also decreased).The results showed that when the nozzle inclination was greater than 85°or less than 40°,there was little effect on the change of airflow field;when the nozzle inclination was 40°-85°,the spraying height was basically linear with the nozzle inclination with the increase of nozzle inclination.This study provides a theoretical basis for the automation of simulation spray.