磨料射流与电火花复合加工技术喷嘴内流场速度分布研究

Study on Velocity Distribution of Flow Field in Nozzles for the Composite Machining Technology of Abrasive Jet and EDM

摘要: 磨料射流与电火花复合加工技术是一种用来提高工件加工质量和加工效率的新型加工技术，射流流体在喷嘴内流场和喷嘴出口处的速度分布对工件加工过程会产生重要影响。通过建立喷嘴内流场的有限元模型和改变喷嘴入口尺寸和入口速度，本文研究了喷嘴工作液入口尺寸、磨料入口尺寸、喷嘴出口尺寸、工作液入口速度、磨料入口速度对喷嘴内部流场和喷嘴出口处速度分布的影响，结果表明：随着工作液入口尺寸和磨料入口尺寸的增加，喷嘴出口处速度值都会增加，但速度分布均匀性却相应变差；喷嘴出口尺寸的增加，会导致喷嘴出口处速度值的降低，但速度分布均匀性变化不大；低速时，磨料入口速度增加对喷嘴内部流场的速度分布状况影响不大，而高速时影响较大；对于不同的工作液入口速度，喷嘴内部流场的速度分布大致一致，速度较大部分主要分布在工作液入口与喷嘴出口连线下部区域。本文的研究结果可用于优化喷嘴的内部几何结构。

Abstract: The composite machining technology (CMT) of abrasive jet (AJ) and electrical discharge machining (EDM) is used to improve the machining quality and efficiency of the workpiece, and the velocity distributions of flow felid of jet fluid in the nozzle and at nozzle exit have important influences on machining process of the workpiece. By establishing the finite element model of the flow field in the nozzle and changing the inlet diameter and inlet velocity of the nozzle, effects of inlet diameter for working fluid, inlet diameter for abrasive, outlet diameter for nozzle, inlet velocity for working fluid, inlet velocity for abrasive, on the velocity distributions of flow fields in nozzle and at nozzle exit, are studied. The results show that the velocities at the nozzle exit increase with the increase of inlet diameters for working fluid and abrasive, however, the distributions of velocity uniformity are worse in these cases; the velocities decrease with the increases of the outlet diameter for the nozzle, and the distributions of velocity uniformity are not much changed; the velocity distributions of flow field in nozzle change a little with the increases of inlet velocity for abrasive at low speeds, however, influences are greater at the high speed cases; for different inlet velocities of working fluid, the velocity distributions of flow field in nozzle have almost the same trend, and the velocities with great values locate mainly below the line between the working fluid inlet and the nozzle outlet. The results in this paper can be used to optimize the internal geometry of the nozzle.