多种约束流道环境下的软性磨粒流流场特性

Flow field characteristics of soft abrasive flow in multiform restraint flow passages

为了解决软性磨粒流加工中工件表面特定加工区域材料去除的难题,提出了一种通过改变约束模块结构控制约束流道内流场的方法。基于标准k-ε湍流模型和Mixture两相流模型,建立了面向液-固两相软性磨粒流湍流流型分析的动力学模型。以波浪形和矩形2种约束流道为具体模拟仿真对象,研究软性磨粒流流经2种约束流道过程中压力、速度等工艺参数。研究结果表明:简单流道内的湍流动能小于复杂流道内的湍动能,因此在流道内加入约束模块可提高湍流的紊乱程度;流道加工表面的静压力、动压力在波浪形约束模块作用下比在矩形约束模块的作用下流道性能有所提高,同时在波浪形流道内可根据约束形状形成明显的压力差值;加入不同形状的约束模块改变流道横截面积,可以改变加工表面压力、速度、磨粒入射角等工艺参数,并且能够获得更加明显的小涡流以提高加工精度。数值模拟结果为软性磨粒流加工工艺参数的选择提供了依据并部分通过试验得到验证。

In order to solve the problem of material removal in some specific regions of workpiece in softness abrasive flow machining,a method based on designing different restraint component structure to control flow field in constrained flow passage was proposed.A dynamic model of solid-liquid two-phase abrasive flow oriented to SAFM was established for physical parameters analysis by using standard k-ε model and Mixture model.Taking undulation and rectangle flow passages to be specific subject to emulate,some processing parameters were investigated,such as velocity and pressure.The results show that the value of turbulence kinetic energy in complex flow passage is larger than simple flow passage,so complex restraint components drive turbulence more random.Compared with rectangle flow passage,static pressure and dynamic pressure in the workpiece surface of undulation flow passage get increased and form differential pressure obviously according to the shape of restraint component.Processing parameters such as pressure,velocity,abrasive,incident angle,etc.can be changed by different restraint component and different cross-sectional area in flow passage,and small eddy can be produced to enhance machining precision.The processing parameters can be selected on the basis of numerical simulation results which were partly proved by experiment.