Effects of Chamber Perforations, Inlet and Outlet Pipe Diameter Variations on Transmission Loss Characteristics of a Muffler Using Comsol Multiphysics

Abstract

Confronted with noise disturbance during transmission of vehicle exhaust air, several mufflers have been designed to control the noise and improve the transmission characteristics. In order to optimize the noise control and attenuation quality, the internal geometry, inlet and outlet pipe diameters of a designed muffler were varied and the performance evaluated using finite element method (FEM). Furthermore, 2mm diameter equal circular perforations were introduced in the resonator chamber to verify the effect on the transmission loss characteristics. The results show that the performance of the muffler with inlet pipe diameter variation is significantly better (68dB) than the standard muffler (55dB) in controlling and reducing acoustic wave propagation within the same frequency range of (200~580Hz). The performance improved further to 70 dB by the introduction of circular perforations in resonator chamber. However, with the variation in the outlet diameter increase the performance of the muffler was 55dB but within a higher frequency range of 220~680Hz which is not reliable for acoustic wave propagation control. The average transmission loss performance of the designed mufflers were 48.62, 47.77, 39.01 and 37.77dB for the resonator chamber perforation, inlet pipe diameter increase, outlet pipe diameter increase and standard muffler respectively. Therefore, the designed muffler with resonator chamber perforations is the best for optimal acoustic wave control.

Study of acoustic and aerodynamic performance of reactive silencer with different configurations: Theoretical, modeling and experimental

“…The acoustic analysis in the frequency domain is governed by Helmholtz equation, equation number 8, which is expressed as follows (Eq. (8) ) [ [28] , [29] , [30] ]. where p is the sound pressure, ω is angular frequency, ρ material density and c is the sound speed.…”

“… All solid surfaces that include the outer walls of the expansion chamber, silencer inlet and outlet tubes, baffle and extended tubes were considered as sound hard boundary and soundproof [ 30 ]. A combination of input and output flat waves was considered for the input surface of the silencer (Eq.…”

“…All solid surfaces that include the outer walls of the expansion chamber, silencer inlet and outlet tubes, baffle and extended tubes were considered as sound hard boundary and soundproof [ 30 ].…”

Detection of hazardous greenhouse gases and chemicals with topological edge state using periodically arranged cross-sections

“…The proposed model possesses two adjacent 1D-PnCs. Each 1D-PnC consists of ternary periodic muffler tubes [28] with different cross-sections, as depicted in figure 1. The geometrical parameters of the first PnC (PnC1) are d 1 (thickness of the first layer), d 2 (thickness of the second layer), d 3 (thickness of the third layer), N (number of periods), S 1 (cross-section of the first layer), S 2 (cross-section of the second layer), and S 3 (cross-section of the third layer).…”

Simulation study of gas sensor using periodic phononic crystal tubes to detect hazardous greenhouse gases

“…1 . The unit cell consists of two cavity muffler tubes 28 with different thicknesses and cross-sections. This unit cell is repeated for N finite periods to make a PnC crystal.…”