Aerodynamic Design Analysis And Study Of Surge Mechanism Of Low Specific Rotational Centrifugal Compressor

Centrifugal compressor plays an important role in the military and civilian fields,is an exhaust gas turbocharger,micro small turbojet and turbofan engine important boosting system,with the advancement of science and technology and the growing demand for supercharging,it is of great significance to develop and design a centrifugal compressor with high total pressure ratio,high absolute efficiency and wide working range.In order to further improve the pneumatic performance of the compressor,it is necessary to systematically study the internal flow field and surge principle of the compressor to provide strong support for the pneumatic performance design of the compressor.According to the design requirements,the geometric model of the low-specific rotational compressor is established,and the flow characteristics and flow laws of the internal flow field of the compressor are analyzed by numerical calculation method,and the principle of surge vibration is studied and the corresponding conclusions are drawn.The main contents of this article are as follows:1.ANSYS-Workbench platform integrates CFTurbo through-flow design module,ICEM meshing module,Turbo Grid meshing module,CFX numerical simulation calculation module,and establishes a low-specific speed centrifugal compressor design and flow analysis platform.Based on the platform,the pneumatic performance of compressors with low specific rotational speed was carried out;2.According to the outlet boundary condition of different mass flow at different speeds,under the speed near the rated speed and rated speed range,the surge critical point and the blockage critical point are continuously approached by fine-tuning the mass flow,and the characteristic parameters of the compressor under different working conditions are obtained through simulation calculation,and the characteristic curve of the compressor is drawn according to the calculation results;3.The distribution characteristics of flow parameters such as static pressure,velocity and relative Mach number in the centrifugal compressor under design conditions are analyzed in detail.The generation of air flow separation and the development law of vortex in the compressor are analyzed.The analysis results show that the low specific speed compressor has good pressurization effect,the flow is stable under rated conditions,and the pressure ratio and speed meet the design requirements;4.The prediction method of compressor surge boundary is discussed,and the reasonable and effective judgment criterion of compressor surge is obtained.The flow characteristics of near surge working point,surge critical point at different speeds,near peak efficiency point,blocking critical point and the surge principle of low specific speed centrifugal compressor are deeply analyzed.Through the aerodynamic design,performance analysis and the study of the surge principle of the centrifugal compressor,it is concluded that the internal flow of the compressor is extremely complex.In the case of constant speed,when the intake volume is reduced to a certain extent,it causes the occurrence of surge phenomenon;the design points of the shape line of the hub rim,the blade shape,the blade inlet angle of attack and the impeller outlet width will cause the occurrence of the compressor surge phenomenon to a certain extent;the stable working range of the low-specific centrifugal compressor is smaller,and the surge phenomenon is more likely to occur;the surge boundary is predicted by numerical calculation methods,which can provide a very valuable reference significance for solving the surge problem in the actual problem.