Research On Key Technology Of Reverse Engineering For Axial Flow Fan Blade With Feature And Constraint

Axial flow fan has the advantages of simple structure,low noise,and large flow,and it is widely used in metallurgy,chemical industry,food,subway construction and other fields.The blade is the core component to ensure the axial flow fan aerodynamic performance and work efficiency,the surface geometry of complex,how to design the blade with excellent performance has become a hotspot and difficulty.The development process of the traditional wind turbine blade aerodynamics and geometric design,test and modify,structure calculation and analysis and other aspects,the long development cycle,high cost,difficult to meet the modern market demand for rapid product development.Study on the use of some of the excellent performance of the axial flow fan blade product reverse design and optimization,and can greatly shorten the new product development time and reduce the cost.The axial flow fan in reverse,a type of wind turbine blade material for research on Key Techniques of reverse axial flow fan blade in this paper,including the axial flow fan blade surface digitizing measurement data,the original point cloud data preprocessing,feature constraint based on the technology of surface reconstruction.The axial flow fan in the digitalization process,using the portable 3D laser measuring instrument Handyscan 3D by adding the auxiliary plane of the axial flow fan blade surface data acquisition,research a set of meet the axial acquisition methods of data flow fan blade surface.The data preprocessing step,according to the "point cloud noise removal,point cloud data preprocessing,data reduction,data segmentation repair" process has been developed for the axial flow fan blade,simplify the preprocessing step,improves the efficiency of pretreatment.Study on the reconstruction of the blade of axial flow fan,according to the characteristics and constraints of the two aspects of surface reconstruction.Focus on the section line of the original point cloud data surface reconstruction technology based on the blade section data,piecewise fitting establish the constraint relationship between each section curve of blade section line reconstruction,ensure the aerodynamic performance of the blades of gas.According to the analysis of the numerical stability of constrained curve fitting in reverse engineering,the curve fitting using least square method,as a constraint expression parameters constrained curve fitting curve,the establishment of mathematical model,and the fitting function Hessian matrix condition number of numerical analysis.Results show that with the number of conditions of Hessian matrix geometric center of fitting the data change increases rapidly and lead to the result cannot converge.In order to understand the original product from the true sense of the original design features,explore the axial flow fan blade,based on laser scanner point cloud data is proposed.Using three order spline fitting blade and arc to get the axial flow fan blade body parameters and restore the original design intent design parameters.According to the research work of this thesis,based on a type of axial flow fan blade 3D reverse engineering examples,summed up a set of high accuracy,high efficiency characteristics and constraints of the axial flow fan blade based on Reverse Engineering technology.At the same time,using the feature constraint reconstruction technology for repairing blade in the actual operation,and provides a more accurate repair plan.