Acoustic Transmission Through a "3-D" Orthotropic Multi-Layered Infinite Cylindrical Shell, Part II: Validation and Numerical Exploitation for Large Structures

Blaise, A.; Lesueur, C.

doi:10.1006/jsvi.1994.1148

Cited by 33 publications

(20 citation statements)

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“…In order to validate reliability of the presented work, the results are compared with those of Blaise and Lesueur (1994b), which considered the 3D wave propagation into a thin cylindrical shell ignoring the internal and external airflow (Figure 4). The comparison has been performed in a frequency band between 100 to 5000 Hz.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…Then, by the displacements and stresses fields, it was possible to get the sound transmission loss of the double-wall thick cylinder. Due to lack of studies in the field of thick-walled shell, the theoretical model and the numerical code have been validated by the means of models of thin shells (Koval, 1976; Blaise and Lesueur, 1994; Daneshjou et al., 2010) which provide excellent agreement with each other.…”

Section: Discussionmentioning

confidence: 99%

“…The other two terms involving the wave number components can be rewritten using equation (2) that is shown below (Ghinet et al., 2006; Liu and He, 2016b): where Ω and kor are auxiliary angle and the radial component of the wavenumber, respectively, which can be presented as: Substituting equation (3) into equation (1) and then simplifying the harmonic incident wave in the cylindrical coordinates on the external space can be obtained as follows (Ghinet et al., 2006; Liu and He, 2016b): where εn is Neumann factor given by:

where J n is Bessel function of the first kind of integer order n . The waves reflected from the cylindrical shell can be represented as (Blaise and Lesueur, 1994, 1992): where Hn 2 is Hankel function of the second kinds of order n , and Pr o is unknown amplitude of the diffracted wave. The wave equations in the external space can be demonstrated as (Howe, 1998): ∇2 is Laplacian operator in the cylindrical coordinate system, whereas boldVboldo(0,0,Vo…”

Section: Theory and Formulationmentioning

confidence: 99%

“…For a resonant air-gap, the incident (PI G) and reflected (PR G) pressures are given by equations (10) and (11) as (Blaise and Lesueur, 1992, 1994; Liu and He, 2016a): …”

Section: Theory and Formulationmentioning

confidence: 99%

“…The TL of the shell is obtained from the ratio of incident sound power WI(ψ,γ) to transmitted sound power WT(ψ,γ) through unit length of the cylinder (Blaise and Lesueur, 1994; Fahy, 2002; Liu and He, 2016b). where, WT(ψ,γ) is the n-th terms of the transmitted sound powers corresponding to the n-th mode: …”

Section: Definition Of Sound Transmission Lossmentioning

confidence: 99%

See 4 more Smart Citations

Investigation on sound transmission through thick-wall cylindrical shells using 3D- theory of elasticity in the presence of external and mean air-gap flow

Daneshjou

Talebitooti

Tarkashvand

2016

Journal of Vibration and Control

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This paper studies the effects of an external mean flow and an internal air-gap mean flow on sound transmission through a double-wall thick cylindrical shell. Due to the major influence of some effective terms such as membrane, bending, transverse shearing and rotational inertia on thick-walled shell, three-dimensional theory of elasticity is used to obtain the governing equations of motion. Therefore, Newton’s second law is utilized to develop the equilibrium equations for an infinitesimal element in cylindrical coordinates. Then, the equations of motion related to the circular hollow cylinders are solved using Helmholtz potentials for arbitrary values of physical and geometrical parameters. In addition, by coupling of both inner and outer shells, a modal transfer matrix is created. This modal matrix stands for the global dynamic equilibrium of the double-wall cylinder. Moreover, the sound transmission Loss of the double-wall cylinder excited by an acoustic oblique plane wave with two angles of incident (i.e. elevation and azimuth angles) is predicted. Due to lack of studies in the field of sound transmission through the thick-walled shell, the results obtained in this study are compared with those from other researchers for a thin cylindrical shell. These results indicate an excellent agreement in comparison with each other. Furthermore, the results reveal that with thickening of the shell, critical and coincidence frequencies are getting closer to ring frequency. Moreover, the effects of external and air-gap flows on TL behave in similar way whereas the Mach number is positive. In addition, an improvement of transmission loss can be found whereas the Mach number is negative; particularly this enhancement is more specified for the external flow. Finally, the results indicate that where both external and air-gap fluids simultaneously flow in opposite directions [Formula: see text] the TL is significantly enhanced. However, for the case where these two fluids flow in the same direction [Formula: see text] the TL is decreased.

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Section: Numerical Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Theory and Formulationmentioning

confidence: 99%

“…For a resonant air-gap, the incident (PI G) and reflected (PR G) pressures are given by equations (10) and (11) as (Blaise and Lesueur, 1992, 1994; Liu and He, 2016a): …”

Section: Theory and Formulationmentioning

confidence: 99%