小型撞击流反应器内流动特征、混合机理及强化手段研究

发布时间：2018-12-16 08:58

【摘要】：撞击流技术作为强化混合的重要手段,已在煤气化、聚合注射成型、细胞破碎等领域得到成功应用。掌握撞击流流动特征及混合机理,对撞击流反应器的研发、设计及运行参数的优化有重要指导意义。本文以撞击流反应器为研究对象,采用粒子图像测速仪(Particle Image Velocimetry,PIV)等实验仪器及图像处理方法对小型撞击流反应器内流动特征及混合特征进行了冷态实验研究,考察了激励对流动及混合的影响。主要内容如下：1.采用粒子图像测速仪和高速摄像仪研究了喷嘴射流Reynolds数在100～2000范围内撞击流反应器内流动特性。结果表明：随着Reynolds数增大,撞击流反应器内依次出现分离流、偏斜振荡、轴向振荡及旋涡脱落模式。其中,当Re≈300时,反应器内流动模式由偏斜振荡转化为轴向振荡。偏斜振荡是由射流不稳定性与撞击不稳定性共同作用引起,并由撞击面与反应器内壁的相互作用维持；而射流入口扰动和反应器受限边界条件是产生轴向振荡的主要原因。2.利用粒子图像测速仪、高速摄像仪及热线风速仪研究了激励作用下撞击流反应器内撞击面的振荡特性。结果表明,激励作用能够诱导撞击面周期性的振荡,撞击面振荡频率与激励频率基本相等,振幅随着激励频率的增加而减小。当Re≤100时,激励作用能够诱导撞击面产生不同尺度的旋涡,旋涡的尺度随激励频率的增加而减小。3.运用平面激光诱导荧光技术考察了激励作用对撞击流反应器内混合效果的影响。结果表明,当撞击流反应器内处于分离流模式时,两股流体间的混合效果较差；当流动模式转变为自持振荡时,两股流体间的混合效果显著提升,说明Reynolds数是影响流体混合的关键因素。当流动模式为分离流时,激励作用能够较好地改善流体的混合效果；当流动模式处于自持振荡时,激励对流体的混合效果影响较小。
[Abstract]:Impinging flow technology, as an important means of enhancing mixing, has been successfully applied in the fields of coal gasification, polymer injection molding, cell breakage and so on. Mastering the characteristics of impinging flow and mixing mechanism is of great significance to the research and development of impinging flow reactor, design and optimization of operation parameters. In this paper, the cold flow characteristics and mixing characteristics in a small impinging flow reactor are studied by using particle image velocimetry (Particle Image Velocimetry,PIV) and image processing methods. The effects of excitation on flow and mixing are investigated. The main contents are as follows: 1. Particle image velocimeter and high speed camera were used to study the flow characteristics of jet Reynolds number in impinging flow reactor in the range of 100,2000. The results show that the separation flow, skew oscillation, axial oscillation and vortex shedding mode appear successively in the impinging flow reactor with the increase of Reynolds number. When Re 鈮，

本文编号：2382098