Study On The Performance Of Silencing And Improved Design Of Intake Silencer Used In Marine Diesel Engines

To effectively improve the power of diesel engines,most marine diesel engines are equipped with a supercharger.But bring benefits at the same time,also produce the high frequency noise,which is relatively large noise.High-frequency noise is too harsh to human,the human body and mind will have a great impact.In the face of military demand.Too much noise will have greatly affect to ship's hidden.At present the research in the field of diesel exhaust noise have made satisfactory achievement,however the research of intake and noise reduction is lacked.Therefore,it is necessary to analysis the intake silencer of marine diesel engine.In this paper,by numerical simulation and experimental test to verification the method,which use the acoustic finite element software Virtual.Lab to calculate the the acoustic performance of the muffler is right and feasible.The influence of the distance between sound-absorbing plates,the diameter of sound-absorbing plates and the perforated plate on both sides of silencer on the transmission loss were analyzed.Besides,design of orthogonal test method to improve the acoustic attenuation performance of intake silencers for marine.Research work and achievement of this paper are as follows:1.The acoustic finite element model including air and sound absorbing material based on acoustic finite element method by Virtual.Lab.A method of calculating the performance of muffler was summarized,by numerical simulation to calculate the transmission loss of muffler.2.The transmission loss experiment was carried out in the semi-anechoic chamber to verify the correctness of the finite element model of the intake silencer of marine diesel engine.Built a performance test platform of muffler acoustic performance in semi-anechoic chamber.By comparing the experimental results with the results of the numerical calculation of the muffler,the feasibility and rationality of the method are proved.3.The influence of the distance between sound-absorbing plates,the diameter of sound-absorbing plates and the perforated plate on both sides of silencer on the transmission loss were analyzed.The results show that the transmission loss of the silencers increases by about 2.5 dB with the each 2 mm reduction in the distance between the sound absorbing plates.In most frequency range,the transmission loss of the silencer is increased by 1 to 2dB with the sound-absorbing material for each additional 40 mm diameter.The acoustic attenuation performance of the improved silencer increases by about 8dB form 800~1600Hz.4.On the basis of the influence of the structure parameters of the performance on the transmission loss of muffler.The effects of the distance between the sound absorbing plates,the diameter parameters and the perforation of the perforated plates on the performance improvement of the muffler were comprehensively analyzed.Orthogonal test method was used to select the best improved design scheme.The improved silencer design has been improved over the entire frequency range.The acoustic attenuation performance of the improved silencer increases by about 4dB and 12 dB,which form 100~800Hz and 1000~6300Hz.which is conducive to suppress the inlet noise of the turbocharger.And provide a basis for improving the design of the muffler.