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Effects of an internal flow on the vibration of thin cylindrical shells
 Date Issued:
 1990
 Summary:
 The response and the dynamic stability of thin cylindrical shells excited by a point force with an internal heavy medium (water) moving with a constant mean flow velocity are investigated. Two sets of analysis are discussed, one for infinitely long shells and one for shells of finite length. The infinite condition applies to shells which are sufficiently long to be considered infinite. In this case, the solution is obtained by means of a spatial Fourier transform in the axial direction and a modal decomposition in the circumferential direction. Using this solution, input and transfer accelerances are determined. The results of this part of this analysis show that input accelerances are globally preserved as the mean flow velocity changes. For the transfer accelerances, broadband peaks appear which are caused by the phase matching between propagating waves of different mode numbers. These broadband peaks are shifted and modified by the mean flow velocity. For shells of finite length, simply supported boundary conditions are assumed. In this case, the response is obtained by using a normal mode expansion of the in vacuo shell and the KirchhofHelmholtz equation derived for a fluid moving at constant flow velocity and bounded by a perfectly rigid cylinder. For finite shells, the main effect of the flow on the response is to decrease the natural frequencies of the shell. The extent of the change in frequency depends on the circumferential and axial mode numbers. Experimental results are also presented for a pipe shell of radius 0.025m and wall thickness 1.5mm. These results are compared with the analytical results for similar shell and flow condition and the agreement is very good. Using the analysis developed for the response, results are presented on the instabilities that can be induced by the flow. It is found that these instabilities are not restricted to finite pipes, but can also exist for cylindrical shells of infinite extent.
Title:  Effects of an internal flow on the vibration of thin cylindrical shells. 
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Name(s): 
Leyrat, Gilles F. Florida Atlantic University, Degree grantor Cuschieri, Joseph M., Thesis advisor College of Engineering and Computer Science Department of Ocean and Mechanical Engineering 

Type of Resource:  text  
Genre:  Electronic Thesis Or Dissertation  
Issuance:  monographic  
Date Issued:  1990  
Publisher:  Florida Atlantic University  
Place of Publication:  Boca Raton, Fla.  
Physical Form:  application/pdf  
Extent:  245 p.  
Language(s):  English  
Summary:  The response and the dynamic stability of thin cylindrical shells excited by a point force with an internal heavy medium (water) moving with a constant mean flow velocity are investigated. Two sets of analysis are discussed, one for infinitely long shells and one for shells of finite length. The infinite condition applies to shells which are sufficiently long to be considered infinite. In this case, the solution is obtained by means of a spatial Fourier transform in the axial direction and a modal decomposition in the circumferential direction. Using this solution, input and transfer accelerances are determined. The results of this part of this analysis show that input accelerances are globally preserved as the mean flow velocity changes. For the transfer accelerances, broadband peaks appear which are caused by the phase matching between propagating waves of different mode numbers. These broadband peaks are shifted and modified by the mean flow velocity. For shells of finite length, simply supported boundary conditions are assumed. In this case, the response is obtained by using a normal mode expansion of the in vacuo shell and the KirchhofHelmholtz equation derived for a fluid moving at constant flow velocity and bounded by a perfectly rigid cylinder. For finite shells, the main effect of the flow on the response is to decrease the natural frequencies of the shell. The extent of the change in frequency depends on the circumferential and axial mode numbers. Experimental results are also presented for a pipe shell of radius 0.025m and wall thickness 1.5mm. These results are compared with the analytical results for similar shell and flow condition and the agreement is very good. Using the analysis developed for the response, results are presented on the instabilities that can be induced by the flow. It is found that these instabilities are not restricted to finite pipes, but can also exist for cylindrical shells of infinite extent.  
Identifier:  12249 (digitool), FADT12249 (IID), fau:9155 (fedora)  
Collection:  FAU Electronic Theses and Dissertations Collection  
Note(s): 
College of Engineering and Computer Science Thesis (Ph.D.)Florida Atlantic University, 1990. 

Subject(s):  Shells (Engineering)Vibration  
Held by:  Florida Atlantic University Libraries  
Persistent Link to This Record:  http://purl.flvc.org/fcla/dt/12249  
Sublocation:  Digital Library  
Use and Reproduction:  Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for nonprofit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.  
Use and Reproduction:  http://rightsstatements.org/vocab/InC/1.0/  
Host Institution:  FAU  
Is Part of Series:  Florida Atlantic University Digital Library Collections. 