关键词: 混药器, 射流, 空化, 植保机械, CFD

Abstract: 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.

Key words: mixer, jet, cavitation, plant protection machine, CFD