Structural And Performance Study Of The Vehicle Exhaust Muffler

Vehicle noise not only has certain effect on human health,social and economic development,but also affects the driving safety.Exhaust noise should be effectively controlled as one of the most important noise sources of the whole vehicle.The easiest and most effective way to control exhaust noise is to install an exhaust muffler.However,the muffler needs to consider the aerodynamic performance while considering the acoustic performance,otherwise it will affect the power of the automobile engine and reduce fuel economy.Therefore,the development and design of muffler with good performance has critical practical and social significance.The automobile exhaust muffler is composed of a basic muffler unit such as expansion,resonance,and dissipative muffler.GT-Power software was used to calculate and analyze the pressure loss of the basic muffler unit.The influence of the length of the insertion tube on the pressure loss of the insertion tube muffler unit,the influence of the perforation diameter and the perforation rate on the pressure loss of the perforated plate muffler unit,and the influence of the cavity arrangement on the pressure loss of the resonant muffler were studied.The results show that the pressure loss of the insertion tube muffler unit decreases with the increase of the insertion length of the inlet and outlet tubes.The pressure loss of the perforated plate muffler unit decreases with the increase of the perforation aperture.The pressure loss of the perforated plate muffler unit decreases significantly with the increase of the perforation rate.Structural factors have little effect on the pressure loss of the multi-cavity resonant muffler.GT-Power and Virtual.Lab software were used to analyze the transmission loss of the basic muffler unit.The influence of the length of the single-expansion insertion tube and the length of the double-expansion insertion tube on the transmission loss of the insertion tube muffler unit was analyzed.The study found that the pass frequency can be effectively eliminated by adjusting the length of the insertion tube.The influence of perforation diameter and perforation rate on the transmission loss of perforated plate muffler unit was analyzed.The study found that the acoustic performance is improved as the perforation rate is reduced.The effect of different cavity arrangement on the transmission loss of resonant muffler is studied.It is found that the series resonant muffler produces the same number of resonant peaks as the number of resonant cavities.By increasing the spacers in the resonant cavity,acoustic energy attenuation at more frequencies can be achieved.The parallel resonant muffler can generate multiple resonant peaks,and the muffler has better noise cancellation effect in a wider frequency band.The series-parallel resonant muffler not only has multiple resonant peaks,but also achieves wide-band noise attenuation.The muffler transmission loss test bench was built to study the test measurement method of the muffler transmission loss.The transmission loss of the resonant muffler was measured on impedance tube by using two load methods.By comparing with the test results,GT-Power software has been verified for simulation accuracy in the low frequency range,which provides a basis for the design and development of the muffler.