直接注入式在线混药系统静态混药器设计与试验

Design and Experiment of Static Mixer for Direct Injection Inline Mixing System

摘要:

在线混药技术可以有效解决传统预混药方式存在的威胁操作人员健康、污染环境及药液浪费等问题。设计了一种应用于在线混药系统的静态混药器。为验证其工作性能，应用CFD流体仿真软件对在线混合流场的混合规律进行研究，采用单因素试验、Plackett-Burman试验和Box-Behnken中心组合试验，以静态混药器压降及混合均匀性系数作为评价指标，基于响应面法分析倾斜扰流板倾角、中心通孔孔径、混药单元间距、过流小孔孔径对评价指标的影响。通过遗传算法进行较低压降和较高混药均匀性系数的多目标优化，得出最佳结构参数为：倾斜扰流板倾角55.38°，混药单元间距22.64 mm，过流小孔孔径1.64 mm。搭建在线混药器试验台架，开展药液注入电动调节阀开度为33%、药泵保持工作、水泵切换不同工作挡位条件下的压降及混药均匀性台架试验，结果表明在雷诺数5 984~13 286范围内，压降呈上升趋势，压降比小于等于106.7；均匀性变异系数呈波动下降趋势，均匀性变异系数小于等于0.008 5，说明所设计静态混药器工作性能较好。

Abstract:

In-line pesticide mixing technology offers an effective solution to challenges such as health threats to operators, environmental pollution, and the wastage of pesticide solutions associated with traditional premix methods. Focusing on the design of a static mixer intended for use in an in-line pesticide mixing system, to verify optimal performance, the mixing characteristics of the in-line flow field were investigated through computational fluid dynamics (CFD) simulations. Single-factor test, Plackett-Burman test, and Box-Behnken center combination test were employed to evaluate the static mixer pressure drop and mixing uniformity. The impacts of parameters such as tilt spoiler angle, center through-hole diameter, mixing unit spacing, and flow-through hole diameter on the evaluation indexes were analyzed by using the response surface method. On this basis, multi-objective optimization, targeting low-pressure drop and high mixing uniformity was conducted through a genetic algorithm. The optimal structural parameters were determined as follows: spoiler inclination of 55.38°, mixing unit spacing of 22.64 mm, and pore size of 1.64 mm. Bench tests for pressure drop and mixing uniformity were conducted under specific conditions: electric control valve opening for liquid pesticide injection at 33%, continuous operation of the pesticide pump, and variable working gears for the water pump. The results indicated an increasing trend in pressure drop within the Reynolds number range of 5 984~13 286 and the pressure drop factor was less than 106.7. The coefficient of variation for mixing uniformity exhibited a decreasing trend, and it was less than 0.008 5, indicating the reliable performance of the static mixer. The research results can provide reference for the development and structure optimization of static mixer in China.