基于模型与CFD辅助的射流式混药器设计

射流式混药器结构简单，是实现药水分离的最简单有效的关键部件之一。针对混药器内部流体流动过程的复杂性，目前没有通用的理论模型来指导设计计算，没有直观的试验方法观察内部流动的问题。从非弹性介质的动量定理出发，推导出射流式混药器的特性方程，建立面积比、喷嘴与混合室距离的理论计算模型。采用多相流Mixture模型中的Zwart Gerber Belamri空化模型法，模拟分析混药器内部的相变过程。研究结果显示理论模型法、仿真法与试验方法的拟合优度大于0.98，证明研究方法的有效性。射流式混药器在低压力比下会发生空化现象，空化产生的气体使引射流量保持稳定，该特性能够满足稳定的混药比要求。设计面积比为1.31的混药器，混药比为0.049 8，混药比变异系数为123%。引射流体与工作流体在距离喷嘴出口40 mm处，其速度场已趋于一致，即混药器的混药均匀性可以满足实际需求。该研究为射流式混药器研究与应用提供技术支撑。

Design of jet mixer based on theoretical model and CFD assistance

The jet mixer has a simple structure and it is one of the most simple and effective key components to realize the separation of medicine and water. In view of the complex internal fluid flow process of the mixer, there is currently no general theoretical model to guide the design calculation, and there is no intuitive test method to observe the internal flow problem. Based on the momentum theorem of inelastic media, this paper derives the characteristic equation of the jet mixer, and establishes a theoretical model for calculating the area ratio and the distance between the nozzle and the mixing chamber. The Zwart Gerber Belamri cavitation model in the multiphase flow Mixture model is used to simulate and analyze the process of phase change inside the mixer. The research results show that the goodness of fit between the theoretical model method, the simulation method and the test method is greater than 0.98, which proves the effectiveness of the research method. The jet mixer will have cavitation at a low pressure ratio. The gas produced by cavitation keeps the jet flow stable. This feature is conducive to the high requirement of the mixer for the stability of the mixing ratio. The design area ratio of the mixer is 1.31, and the mixing ratio is 0.049 8, and the variation coefficient of the mixing ratio is 123%. The velocity field of the ejector fluid and the working fluid at a distance of 40 mm from the nozzle outlet has tended to be the same, that is, the uniformity of the mixing of the medicine mixer can meet the actual demand. This research provides technical support for the research and application of jet mixer.