Research On Impeller Modeling And Processing Method Based On Mixed Dimension

In small gas turbines and supercharging systems,impellers can improve fuel efficiency and reduce energy consumption,and increase engine output.For impellers with complex shapes,working in a high-temperature,high-speed,and high-pressure environment to compress or transfer fluid,the surface quality has an important impact on the conversion of efficiency.This paper takes the turbocharger impeller as the research object.Firstly,the three-dimensional modeling of impeller based on NURBS curve and surface is studied.According to the data of known value points,the calculation of node vector and control point is realized,the root line and tip line of the blade are fitted with NURBS curve,and the flow channel and hub surface of the impeller are fitted with NURBS curved surface.The three-dimensional modeling of the impeller based on NURBS curve and surface is obtained.It provides macroscopic geometric dimensions for the mixed dimensional modeling of the impeller.Secondly,the mixed-dimensional modeling of impeller with multi-scale correction is studied.W-M fractal function is used to simulate the micro-topography of the impeller surface.The micro-morphology generated by the W-M fractal function is superimposed on the three-dimensional modeling of the impeller to realize the mixed dimensional(3D-fractal dimension)modeling of the impeller.According to the theory of multi-scale analysis of surface topography,discrete wavelet is used to extract multi-scale surfaces of mixed dimensions,andthe decomposed roughness,waviness and shape errors are corrected according to the parameter requirements at each scale.Mixed dimensional modeling of an impeller based on multi-scale correction is obtained.Thirdly,the influence of processing parameters on surface topography is studied.The geometric simulation model of ball end milling and side milling was established,and the simulation of ball end milling of flow channel surface and side milling of blade surface was realized according to the cutting point of impeller finishing machining.The influence rules of feed rate of each tooth,cutting row distance and initial cutting angle on micro morphology were analyzed,which can provide a theoretical basis for the parameter selection of impeller finishing.Finally,the efficient machining path planning method of impeller is studied.The tool paths of sequential grooving,inverted V-shaped grooving,streamline channel finishing and five-axis side milling blade finishing were designed.The machine tool motion simulation of impeller machining was realized in VERICUT.This research provides references for multi-scale forward modeling,efficient and high-quality processing methods of turbocharger impellers.