Analysis For The Influence Of Machining Error On Centrifugal Impeller Aerodynamic Performance

Centrifugal compressors are widely used in the national economy departments. Along with the continuous expansion of industrial production, centrifugal compressor is developing toward high parameters, high performance, high reliability, low energy consumption. This thesis, in which the research focused on the influence rules of blade’s machining error on centrifugal impeller aerodynamic performance is mainly supported by the National Basic Research Program of China (973 Program) named Key Scientific Problems of Super Large-sized and Low Energy Consumption Development of Complex Air Separation Equipment(No.2011CB706505) and the National Natural Science Project named Theory and Method for Tolerance Design Based on Concurrent Function-structure Decomposition (No. 51175466). The main content of this thesis is as follows:In chapter one:The background and significance of the research is expatiated and centrifugal impeller research status at home and abroad is introduced in detail. Research demand and progress of Turbomachinery aerodynamic performance and internal flow field is analyzed. Finally, the research content and general framework of the thesis is given.In chapter two:The theory of centrifugal impeller flow field numerical calculation method is discussed. Firstly, Navier-Stokes controlled equations of the impeller internal flow field and Spalart Allmaras turbulence model are introduced. Then the discrete method of control equation both in space and time are analyzed. Finally, multiple grid technology and implicit residual smoothing method are introduced for accelerating the calculation convergence.In chapter three:Describing and generation method of impeller machining error has been studied. CFD analysis model of the impeller which contains surface profile error is constructed. Impeller grid mesh and grid quality evaluation standard and the setting of boundary conditions are introduced. Finally this thesis introduces the calculation process parameter settings and the numerical calculation process.In chapter four:The flow field simulation about impellers which contain one of local equal thickness type, local variable thickness type and global types of surface profile error is taken under different working conditions. The influence of different types of surface profile error on efficiency and compression ratio and internal flow of the impellers is discussed.In chapter five:Roughness friction efficiency loss model is established, and Newton iteration method is used for solving Colebrook-White formula. The effect of roughness on the impeller efficiency loss is analyzed. And the law of impeller efficiency loss under different reference roughness is presented by figures.In chapter six:The conclusions of the thesis were made, and some further researches are also suggested.