Research On Simulation And Experiment For Acoustic Performance Of Waterpipe Silencer

The transmission loss is an important evaluation index for evaluating the acoustic performance of the muffler in theoretical research,which is only related to the parameters of the muffler itself.For the air filling pipe muffler,the transmission loss is usually measured by two-load method in combination with decomposition method.For the water filling pipe muffler,thick-walled tube is usually used to ensure the plane wave propagation conditions of the sound tube measuring section;However,the thick-walled tube is very heavy and complicated in processing.If use the vertical thick-walled tube,it is difficult to build and requires a complicated auxiliary system.If use the horizontal thick-walled tube in the laboratory,the test cost is low,but the air will remains in the measurement section and the muffler to be tested.This part of air may affect the muffler performance and measurement results.Firstly,in this paper,the acoustic performance of kinds of water mufflers are simulated and the basic acoustic performance of water muffler is obtained.The effect of the perforation structure of the perforated tube muffler and the flexible structure inside the airbag muffler on the transmission loss are analyzed.Then,the influence of the air layer on the transmission loss of muffler was studied.Studies have shown that for the water muffler in the laboratory,the remaining gas in the tube have a greater impact on the acoustic performanceThis paper proposes a vertical thin-walled test bench.The test bench can reduce the influence of the internal air layer by this kind of deployment,and improve the accuracy of measuring the transmission loss of the water muffler by the two-load method.But in the test of the transmission loss of the water muffler of the thin-walled tube,the acoustic-solid coupling affects the accuracy of the transmission loss value.So this paper studies the influencing factors and laws of the thin-walled tube through simulation calculation.These factors include piping materials,piping support,hydrophone installation method,point location,and so on.These simulation results were used as design guidelines for the vertical thin-walled test bench.Finally,this paper designs a vertical thin-walled test bench and studies related experiment.The experimental research includes the measurement and analysis of the wavefront and sound velocity inside the straight pipe and the test bench.The test analysis results and the simulation results have a high consistency.Different liquid level height can build different load conditions.The transmission loss of the muffler under different hydrophone spacing is measured by two-load method,and the optimal hydrophone spacing given by the simulation results is verified.The experimental results show that the transmission loss experimental system of thin-walled tube muffler has high consistency in measuring the transmission loss of seawater muffler in the frequency range of 800Hz?1200Hz,and the system can be used as a substitute for thick-walled tube in the design stage of seawater muffler.