Surface quality control technology of abrasive flow polishing S-shaped elbow

The quality of the inner surface of the elbow used by common types of engines has a serious impact on its performance. In order to improve the machining accuracy of the inner surface and enhance the uniformity of the whole structure, large eddy simulation is carried out for the flow channel in an S-shaped elbow with the abrasive flow by using KET subgrid model. The distribution of flow field, vortex formation law, and the influence of the vortex in the process of polishing surface quality are analyzed, and the processing experiment is carried out. The numerical simulation result shows the inlet pressure determines the inlet velocity of abrasive particle flow. Higher inlet pressure will significantly increase the shear force, improve the uniformity of turbulence kinetic energy distribution on the elbow wall, and increase the number of abrasive flow vortices. The experiment result shows the changes in inlet pressure and abrasive particle size have a significant effect of the polishing effect on S-shaped elbow. The combination of coarse abrasive and high inlet pressure will produce an over-polishing phenomenon, the inner surface roughness of the elbow can be reduced to 76 nm, and the optimal process parameters determined by the experimental research can achieve the uniform polishing of the S-shaped elbow by the abrasive flow machining technology.