Exhaust Muffler Design and Analysis Using a Boundary Element Method Based Computer Program

Comparison and application of the experimental methods for multi-layer prediction of acoustical properties of noise control materials in standing wave-duct systems

“…Element amplitudes of the transfer matrix calculated from the four-microphone TLM using the RUB material. For the multi-layered treatments of materials in some applications, such as the automotive liners, their acoustical properties usually cannot be directly measured by a one time test in standing wave-duct, therefore, we have to consider predicting them by TCM or TLM through measuring the transfer matrix of each layer and calculating the total transfer matrix of the multi-layered materials by the equations from (10) to (21). Unfortunately, as mentioned before, the TCM and TLM approaches are not always acceptable for any case.…”

Design of a Hybrid Exhaust Silencing System for a Production Engine

“…Noise attenuation characteristics of dissipative silencers have been explored analytically (Scott, 1946a;Cummings and Chang, 1988;Munjal, 2003) and computationally (Craggs, 1977;Peat and Pathi, 1995;Cheng and Wu, 1999;Selamet et al, 2001) using the acoustic properties of absorbents developed, for example, by Scott (1946b) and Delany and Bazley (1970). The acoustic characteristics of perforates in contact with absorbent have also been investigated by Ingard and Bolt (1951), Munjal and Thawani (1997), and Kirby and Cummings (1998).…”

Muffler characterization with implementation of the finite element method and experimental techniques

“…This value is typically assumed to be 1.40 but does vary slightly with temperature, therefore the temperature effects should not be ignored (6). is the molar gas constant (8.31451 ) and is the mean all the peaks and troughs were almost completely removed and there was a general decrease in TL (17,13,27).…”