The Vibro-acoustic Characteristics Of Circular Cylindrical Shells Immersed In Viscous Fluids

The research of the thesis is a part of the project “Characteristics of VibrationalPower Flow in Submerged Coupled Cylindrical shell”, which is supported by the NationalNatural Science Foundation of China (Contract No.40976058). The work is around thevibration-acoustic characteristics of infinite cylindrical shell submerged in viscous fluid.The vibration-acoustic equation of coupled cylindrical submerged in viscous fluid isestablished. The effect of the viscosity of the fluid on dispersion characteristics ofcylindrical shell in free vibration, input power flow and radiated sound power of thecylindrical shell loaded with a cosine harmonic circumferential line force is mainlydiscussed theoretically.First, the research status of this study content related fields is comprehensivereviewed and commented. The analysis methods and research results of vibrational powerflow of cylindrical shell-fluid coupled system is mainly introduced. The processingmethod of the viscous fluid in related issues.The wave equation in the viscous flow field is obtained by combine the smallamplitude wave equation of state and Linearization equations of continuity and N-S. Thevelocity field of viscous fluid is resolved as the superposition of a scalar and a vector. Theexpressions of velocity and stress are obtained by the solution of the wave equation incylindrical coordinates. Then, the vibration-acoustic equation of coupled cylindricalsubmerged in viscous fluid is derived using the boundary conditions and the Flüggeequations.Dispersion characteristic equation of the coupled system in free vibration is derived.The propagating wave is the main object of study when considering vibrational powerflow propagation in a cylindrical shell. The dispersion characteristic curve of cylindricalshell in viscous fluid is obtained by the method of root search along the real axis. Theeffect of the viscosity of the fluid on dispersion characteristics is analyzed by contrast withthe results in the ideal flow field. The effect of the degree of viscosity on dispersioncharacteristics is studied by comparing the dispersion curves under different viscous flowfield.The input power flow curves of infinite cylindrical shell submerged in viscous fluidis calculated by Gaussian integration method when the cylindrical shell is loaded a circumferential line force. The similarities and differences between the results immersedin a viscous fluid or the ideal fluid is compared. The effect of the degree of viscosity oninput power flow is analyzed by changing the viscous fluids.At last, The radiated sound power of the cylindrical shell loaded with acircumferential line force in the viscous fluid is calculated. The effect of viscosity on theradiated sound power is obtained by comparing with the result when the cylindrical shellis submerged in ideal fluid. The effect of the degree of viscosity on the radiated soundpower is studied by comparing the results when the cylindrical shell immersed in differentviscous fluids.