Research On Numerical Simulation Of Aerodynamic Performance Of Exhaust Gas Turbocharger Compressor

With the change of times,the development of science and technology and the change of environment,people pay more and more attention to environmental protection.As the power core of construction machinery,diesel engine has put forward higher requirements for its exhaust emission.Exhaust gas turbocharger plays an important role in energy saving and emission reduction of engine.Its important component is centrifugal compressor,which can make the fuel in the engine fully burn through pressurized air,and produce less air pollution exhaust gas,so as to achieve the purpose of energy saving and emission reduction.The core of centrifugal compressor is impeller,and the pressurized air is realized by its high-speed rotation,so the design of high-efficiency small centrifugal compressor has become a hot research object.In this dissertation,the aerodynamic performance of exhaust gas turbocharger centrifugal compressor is studied by numerical simulation,which can be used for reference in the design and development of centrifugal compressor in the future.Through reading a large number of literature,it is concluded that a large number of scholars have done a lot of research on the impeller and diffuser of exhaust gas turbocharger centrifugal compressor,so this dissertation takes the impeller and diffuser as the research object to carry out the numerical simulation research.In this dissertation,turbocharged diesel engine is taken as an example to match and design the structure of its turbocharger centrifugal compressor,and then the modeling of the compressor passage and the pre-processing of numerical calculation are carried out.Multiple modeling software are used to model,so the modeling should be strictly in accordance with the size,so that the model can be completely displayed in CFD,and there is no superposition or gap at the junction of the model,ICEM CFD software is used for mesh generation,and CFX software is used for numerical simulation.In the process of simulation calculation,it is found that the efficiency and pressure ratio of compressor will change with the change of impeller height,so this dissertation has carried out in-depth research.It is found that under the design flow,when the impeller height is 24 mm,the efficiency is the highest,and the pressure ratio is close to the design pressure ratio.When the impeller height is increased or decreased,the efficiency and pressure ratio are decreased,which indicates that there is an optimal height to make the efficiency and pressure ratio of centrifugal compressor reach the optimal value.Finally,the diffuser was studied.By studying the influence of different upper surface structures of the diffuser on the performance of centrifugal compressor,it was found that the diffuser with first contraction and then diffusion or first diffusion and then contraction had poor performance,while the semi contraction and full contraction diffuser had better performance,and the diffuser with first contraction and then parallel had the best performance,It can restrain the diffusion of upstream vortex and improve the efficiency of compressor.