Abstract:

Impinging stream technology has recently been used to enhance mixing process in the preparation of ultrafine powders due to its good mixing properties. The stability of the impact surface affects the mixing effect in the reactor, so the research on the stability of the impact surface was reviewed. Different structural forms of impinging stream reactors include plane impinging stream, axisymmetric impinging stream and micro impinging stream, etc. A brief description of the experimental research methods of impinging stream stability, the deflection period of the impinging surface of the plane impinging stream reactor and the start and stop conditions of the deflection oscillation of the plane impinging stream were analyzed. It was concluded that the oscillations of the stagnation points of the axisymmetric impinging stream and the plane impinging stream promoted mixing, and the offset oscillation period was indefinite. The offset amplitude of the axisymmetric impinging plane was related to the nozzle distance and Reynolds number. The deflection oscillation period of the plane impinging stream was inversely proportional to the inlet flow velocity. The structural parameters of the reactor were one of the factors affecting the stability of the impinging stream. According to the promotion effect of the axisymmetric impinging stream offset oscillation on mixing, a new set of preset flow waveform double-group impinging stream reactor was proposed. The unique structure of the new impinging stream reactor overcomes the single shortcoming of the material reaction channel, controls its inlet flow through preset waveforms, increases the offset amplitude of the impinging surface, eliminates random vibration of the impinging surface, expands the flow trajectory, and enlarges mixing area. The experimental device and method were designed to discuss the impact of the stability of the impinging surface of the dynamic flow impinging reactor on mixing effect. Finally, the research prospects of the mixing performance of axisymmetric impinging stream reactors were prospected.

Key words: confined impinging stream reactor, impact surface stability, deflection oscillation, offset oscillation, mixing

摘要：

撞击流技术因其良好的混合特性近些年用于强化制备超细粉体反应中的混合过程。撞击面的稳定影响反应器内的混合效果，所以本文对撞击面稳定性的研究进行了综述。撞击流反应器不同结构形式包括平面撞击流、轴对称撞击流和微型撞击流等。文中简述了撞击流稳定性的实验研究手段，分析轴对称撞击流反应器的径向偏转振荡的起止条件和不同喷嘴间距下的轴向偏移振荡规律，并且分析平面撞击流反应器的撞击面偏转周期以及偏转振荡的起止条件。得出轴对称撞击流与平面撞击流撞击面驻点的振荡对混合都有促进作用，并且偏移振荡周期不定，轴对称撞击面偏移振幅与喷嘴间距和雷诺数相关。平面撞击流的偏转振荡周期与进口流速成反比，反应器结构参数是撞击流稳定性的影响因素之一。根据轴对称撞击流偏移振荡对混合的促进作用，本文提出一种新型的预设流量波形双组撞击流反应器。新型撞击流反应器的独特结构克服了物料反应通道单一缺点，通过预设波形控制其进口流量，增大其撞击面偏移振幅，消除撞击面无序振荡，使流动轨迹扩展，扩大混合区域，并设计实验装置与方法讨论动态流量撞击流反应器撞击面稳定性对混合效果的影响。最后，本文对轴对称撞击流反应器的混合性能研究前景进行展望。

关键词: 受限撞击流反应器, 撞击面稳定性, 偏转振荡, 偏移振荡, 混合