Prediction of the vibro-acoustic transmission loss of planar hose-pipe systems

Abstract

Vibro-acoustic energy travels through hose walls as longitudinal waves and flexural waves, apart from the sound waves through the fluid medium inside. Longitudinal waves in the hose wall are coupled to the sound waves inside by means of the hose-wall Poisson's ratio. Both in turn get coupled to bending or flexural waves because of the energy transfer or interaction at the bends. For any of these three types of waves incident on one end of a hose, waves of all the three types may be transmitted on the other end because of their dynamical coupling with one another. Therefore, in the present paper, expressions have been derived for the 3ϫ3 transmission loss matrix for a two-dimensional or planar piping system in terms of elements of the overall 8ϫ8 transfer matrix of the system. These expressions have then been used in a comprehensive computer program to evaluate the vibro-acoustic performance of hoses, with particular application to the automotive climate control systems with gaseous as well as liquid media. Finally, parametric studies have been made that have led to some general design guidelines.

Wavelet analysis of sound signal in fluid-filled viscoelastic pipes

“…The complex wave speed (complex valued and frequency dependent) is used in the standard impedance or transfer matrix method to analyze the oscillatory flow. A similar method has been proposed by Munjal and Thawani (1997) who applied the concept of transmission loss instead of the concept of wall impedance. An extended method, which uses the static mechanical properties and frequency-dependent mechanical properties of the pipe wall, has been proposed by Yu and Kojima (1998).…”

Analysis of wave propagation in fluid-filled viscoelastic pipes

“…A similar method applies the concept of transmission loss instead of the concept of wall impedance [3]. The Poisson-coupled vibrations in an elastic pipe and the fluid in the pipe could potentially yield transfer matrix relations relating the amplitude quantities of motion transmitted through a length of pipe [4].…”

Prediction of the transmission loss in a flexible chamber

“…Nevertheless, there exists an important lack of information about the influence of structural phenomena on the transmission properties, being of vital importance the quantification of the transmission loss and/or transfer matrix coefficients. For example, Munjal and Thawani [18] analytically showed how transmission loss should increase when decreasing the rigidity of the wall material. Cummings [19] developed a theoretical model describing acoustic attenuation in a flexible walled duct passing through a reverberant space.…”