Abstract: Effects of initial surface roughness, inlet flow velocity and hole diameter on flow field pressure, local pressure difference and shear force of cylinder inner wall were simulated by numerical method. Formation processes of flow field velocity and shear force at the cylinder entrance were detected, then over-polishing phenomenon accrued at the entrance of cylinder inner surfaces was deduced according to the abrasive forces action. Effects of all parameters on wall effect during abrasive flow machining was revealed by abrasive flow machining experiments and simulation. Theoretical analysis and experimental results show that, increasing diameter of round hole or reducing inlet flow rate may improve pressure uniformity of abrasive flow field effectively, initial surface roughness has a weak effect on flow field pressure value and the local pressure difference. Sharp transition of wall surface velocity at the entrance causes a sudden change of shear force, then leads to over-polishing phenomenon of abrasive flow machining. Initial surface roughness Ra=0.296 μm is conducive to weakening wall effect of abrasive flow machining and Ra=4.273 μm is conducive to increasing material removal rate.

Key words:  , flow field pressure, shear force, wall effect, over-polishing phenomenon

摘要： 数值模拟了圆柱内表面的初始粗糙度、入口流速和内孔直径对壁面流场压力、局部压差及剪切力的影响规律，分析了入口处流场速度和剪切力的形成过程，从磨粒切削作用角度剖析了圆柱内表面入口处过抛现象的形成原因，结合磨粒流加工试验揭示了各参数对壁面效应的影响规律。理论分析和试验结果表明：增大圆孔直径或减小入口流速能有效改善磨粒流流场压力的均匀性，初始表面粗糙度对流场压力数值及其局部压差有微弱影响；入口处圆孔壁面速度突变引起剪切力突变，从而导致磨粒流加工过抛现象；初始表面粗糙度Ra=0.296 μm时有利于减弱磨粒流加工的壁面效应，而Ra=4.273 μm时有利于提高材料去除速率。

关键词: 流场压力, 剪切力, 壁面效应, 过抛现象