大涡模拟Smagorinsky模型用于磨粒流精密加工喷嘴的质量控制研究

为研究固液两相磨粒流加工喷嘴小孔过程中的流场分布、涡旋形成规律及涡旋的存在对磨粒流加工的影响机制，采用Smagorinsky亚格子模型对磨粒流加工喷嘴小孔的流道进行大涡数值模拟，并使用磨粒流对变直径喷嘴工件进行加工试验。数值模拟发现磨粒流流体中磨粒与壁面的碰撞与剪切作用随流体的速度增大而增大，同一截面的速度存在速度差，其中还伴随涡旋的存在；通过试验研究发现：经固液两相磨粒流加工后的喷嘴小孔表面质量得到明显提高，喷嘴经过四次不同入口速度的磨粒流加工后大孔处表面粗糙度Ra由1.24 μm降至0.542 μm，小孔处表面粗糙度Ra由1.21 μm降至0.437 μm。结论显示固液两相磨粒流加工技术可有效提高被加工喷嘴工件的内表面质量，加工时同一截面的速度存在速度差，速度差的存在利于涡旋的形成，涡旋的存在利于提高磨粒流加工过程的剪切作用，有助于获得高质量的喷嘴小孔内通道表面。

Research on Quality Control of Abrasive Flow Precision Machining Nozzles Based on Large Eddy Simulation Smagorinsky Model

In order to study the influence mechanism of the flow field distribution, formation of eddies and existence of eddies on the nozzle holes by solid-liquid two-phase abrasive flow machining, the abrasive flow machining was used to polish variable diameter nozzle and the process was calculated with the Smagorinsky sub-grid model of the large eddy simulation. The numerical simulations show that the collision and shear actions between the abrasive particles and the wall increase with the increase of fluid velocity, and the velocity of the same section has a varied velocities, which are accompanied by the existence of eddies. According to the experimental results, the surface quality of the nozzle holes after the solid-liquid two-phase abrasive flow machining is improved significantly. The value of surface roughness Ra at the large holes decreases from 1.24 μm to 0.542 μm and at the small hole decreases from 1.21 μm to 0.437 μm. The conclusions show that the solid-liquid two-phase abrasive flow machining technology may effectively improve the inner surface quality of the machined nozzle holes. There is a velocity difference in the same cross section during machining, the existence of the velocity difference is conducive to the formation of eddies. The presence of eddies is helpful to improve the shearing effect of the abrasive flow machining processes and is beneficial to obtain a high-quality surface of the nozzle holes.