The Numerical Simulation Of The Flow Field And Aerodynamic Noise For A Marine Turbocharger Compressor

Centrifugal compressors are widely used for industries of transportation or power stations, they are important parts of the diesel engines used for vehicles and ships, which have been accepted as effective devices to improve the performance and reduce the emissions of diesel engines. The increasingly stringent emission regulations, engine downsizing and heavy exhaust gas recirculation are likely to push the engine operating conditions toward less efficient,it’s imperative to increase the compressor performance. The ever-growing demand for higher engine power output and the increasing speed of compressors, the aerodynamic noise is too prominent to resolve. In order to improve the aerodynamic efficiency, reduce noise level and enhance the amenity of the living environment for crew, the analysis and optimization for compressor performance has extremely important meanings to research on the noise production mechanism and control method. In this paper, the objective of investigation is a turbocharger compressor used for marine engine, the 3D flow field and the aerodynamic noise were simulated based on the analysis of the flow field and noise field of turbocharger compressor in the domestic and abroad. At last, the optimization of the compressor was executed, in conjunction with the existing data, to improve the aerodynamic performance and reduce noise.Firstly, with the aid of CFD software FLUENT and the data of compressor measured on the testing bench, the steady 3D viscous compressible flow field of a turbocharger compressor was studied based on the finite element model, the intenal flow field characteristics were studied under five different operational rotating speeds: 24300r/min,25800r/min, 26880r/min, 28200r/min, 29100r/min. The changing relation of the pressure ratio and the efficiency with the flow rate was analyzed, and the distribution and interaction effect of the velocity and pressure in the rotor region and diffusion region were further studied.Secondly, different methods were used to analyze the aerodynamic noise field for compressor, which are Aero-Acoustic Analogy(AAA) and Broadband Noise Sources Model,the generation mechanism and the distribution characteristics were studied systematically.The Broadband Noise Sources Model was used to simulate the broadband noise source based on the analysis of steady flow field under the five working conditions, to found the generation mechanism and the distribution characteristics. The discrete noise of the differentobservation points in compressor was analyzed by the Aero-Acoustic Analogy(AAA for short), the effect of the speed and the flow rate on the aerodynamic noise was further studied based on the analysis of unsteady flow field, and the results were compared with the experimental formula.Finally, the optimization of the aerodynamic performance and the noise characteristics for compressor is based on the frontal research, which is focused on the structure improvement of vaned diffuser, different analysis Scheme were designed independently. The effects of the radius and the inlet angle of diffuser vane leading edge on the aerodynamic performance and the flow noise were researched.Through the research work in this paper, the flow numerical simulation methods and the aerodynamic noise numerical calculation methods and their applicability were comprehended more deeply. The characteristics of the flow and noise source were analyzed,furthermore, the noise generation mechanisms was also studied, the optimization schemes of the vaned diffuser structure parameters were designed, which might provide one certain reference value for compressor performance improvement and noise control.