Study On Prediction And Experimental Measurement Of Flow Noise In Pipes With Varying Cross-sectional Area

In the modern life, area-varying pipe is widely used. The gas flow in pipe may produce vibration and flow noise. At present, the study for interior flow noise characteristics in the area-varying pipes is still limited, and the method to reduce the flow noise in the area-varying pipes is important. Therefore, the present thesis will study experimental measurement of flow genenrated noise in the area-varying pipes and discuss the effects of flow velocity and the connecting structures of the area-varying pipes on the flow noise in the area-varying pipes, which may be used to guid the design of area-varying pipes.The large eddy simulation method based on the time-domain computation is used in this paper. The basic principle, computational method and data processing of the large eddy simulation method are introduced, and then the method in applied to predict the flow generated noise in the area-varying pipes. By comparing the numerical predictions and the experimental results, the validity of the method is verified. In addition, the advantages and shortcomings of the large eddy simulation method are analyzed and summarized. A test-bed for flow generated noise in area-varying pipes is designed and constructed. The positions of the microphones were arranged reasonably, so that the flow generated noise in area-varying pipes at different velocities could be measured on the test-bed.The flow generated noise in the area-varying pipes at different velocities is predicted by using the large eddy simulation method and measured with the test-bed, then the effects of different connecting structures on the flow noise in the area-varying pipes are investigated numerically. Some conclusions are drawn according to the results, which may be used to provide the guidance for area-varying pipe designs.