Research On Sub-structure Characteristics Of Exhaust Muffler On Internal Combustion Engine

The transmission loss and the pressure loss of the muffler are important indicators of the performance of the muffler,These will directly affect the muffler effect of the muffler and the power loss of the internal combustion engine.Using the experimental method to verify the acoustic and fluid mechanics simulation software to calculate the accuracy of the muffler performance,and then use the finite element method to study the influence of the characteristic parameters of the exhaust gas muffler sub-structure on the acoustic performance and hydrodynamic performance of the muffler.This paper researched on simple expansion chamber muffler?two exit biased expansion structures?two cavity expansion structure? insert muffler?generally perforated structure?cross flow perforated structure with the change of characteristic parameters by LMS Virtual Lab and Fluent.The results show that: in acoustics,reasonable choice of silencer expansion ratio can achieve better muffler.The muffling effect of the two-outlet biasing muffler is better when the exit offset distance is about 0.6R.Reasonably matched multi-cavity muffler the length of each cavity can increase the amount of noise in the entire muffler band,eliminate the through frequency.Different perforation insertion lengths can cause different frequencies of the muffler peaks,the greater the perforation rate,the wider the range of the full effective silencer band.The silencer of the cross flow muffler is better than the general piercing muffler in the high frequency range.In fluid mechanics,simple expansion muffler has a critical expansion ratio,at this time the muffler pressure loss reaches its maximum.The pressure loss of the two-outlet bias muffler increases as the offset distance increases.The connection between the two cavities in the connection tube bias,as long as the same cross-sectional area to ensure that the pressure loss will almost no change.When the inlet and outlet are coaxial,the longer the length of the outlet is inserted,the smaller the muffler pressure loss,When the inlet and outlet position is biased,the longer the length of the outlet is inserted,the greater the loss of the muffler pressure.When the distance from the rear wall is less than half of the diameter,the muffler pressure loss is large.The pressure loss of the straight-through perforated tube muffler increases with the increase of the perforation rate,which is not related to other factors.The pressure loss of the cross-flow perforated tube muffler decreases with the increase of the perforation rate and the increase of the perforation diameter.