Prediction of the transmission loss in a flexible chamber

Abstract

Acoustic components have been extensively studied supposing perfectly rigid behavior. Although some works have been performed for the radiated sound in the case of a flexible element, an important lack of information exists concerning transmission loss analysis. The current investigation proposes the study for a generic flexible expansion chamber. The analysis has been performed using two different methods: a resolution in the time domain, using a Finite Volume discretization for the fluid domain and a Finite Element discretization for the solid domain, and an approach in the frequency domain, using a Finite Element discretization for both fluid and solid. After studying the rigid case in order to tune up the simulation, the study of the flexible case shows a good agreement among both methods. The comparison of rigid and flexible expansion chambers shows the importance of accounting for these phenomena when the frequency content of the acoustic signal excites the natural modes of the structure.

Prediction of the non-linear aeroelastic behavior of a cantilever flat plate and equivalent 2D model

“…The three-dimensional case uses the Finite Volume Method for solving the URANS equations named in the previous subsection for the uid ow and the elastic solid equations for the plate [46], [47]. To simulate the motion of the solid, an overset region is set around it, in order to ensure maintenance of the overall quality of the mesh.…”

Enhancement of Low-Frequency Noise for Muffler by Optimizing the Space between Three 1-Degrees of Freedom Helmholtz Resonator

“…[17] The quantification of transmission loss using a Helmholtz resonator shows good agreement with the numerical results. [18] To reduce the narrow-band low-frequency noise, the Helmholtz resonator which consists of a chamber connected to the main duct through a neck was initially employed. After that, some researchers [19][20] used Helmholtz resonators as reactive-type attenuators to lessen hydraulic fluid pulsation.…”

Enhancing Sound Transmission Loss in Hybrid Mufflers with Change in Pipe Perforation and Using Absorptive Material

“…There are two primary types of noise that an internal combustion engine produces when it flows through an exhaust system: low-frequency noise (below 800-1000 Hz), sometimes known as "breathing noise," and highfrequency noise (above 800-1000 Hz), sometimes known as "flow noise" (Emoto et al, 2023). Absorptive, reactive, and combination mufflers are the three types of mufflers (Torregrosa et al, 2018). The objective behind absorbtive mufflers is to absorb the sound of exhaust gases.…”