Study On Vibration And Noise And Its Characteristics Of Pipeline Systems Considering Fluid-Structure Interaction

As we all know, liquid-filled pipeline systems exist in many fields, just like marineengineering, biological engineering, electrical industry, petroleum energy industry, nuclearindustry, warships, aircraft device and daily life. Because of the existence of excitation insideand outside as pumps, valves, vibration of basement and cracking of pipelines and so on,vibration and noise of pipelines is induced, and propagating in pipelines. It becomes veryserious in pipeline system of warships. For one thing, the vibration and noise of pipelinesystems can make the pipeline and precision apparatus destroyed, which will affect the run ofpipeline and power system; for another thing, the vibration and noise of pipeline systems canradiate through hull and the process when exchange of inside and outside fluid happens, and itwill affect the conceal of the warship and bring in menace to security.At first, neglecting friction between pipeline and fluid, the model of two most commonpipeline section elements is established, namely, straight and curved pipeline, and the axismotion, flexural motion and torsion motion are included. For straight pipeline, Poissoncoupling is considered, and for curved pipeline, Poisson coupling as well as Bourdoncoupling is considered. Then, the time-domain equations describing vibration of pipelinesconsidering fluid-structure interaction are transformed into frequency domain by Laplacetransformation, and for straight pipeline, twelve fourth order ordinary differential equationsand two second order ordinary differential equations are deduced from the frequency-domainequations; for curved pipeline, using the reference of the method of professor Zhang solvingfour-equation model of axis motion, the analytical solution of curved pipeline is also obtained.In order to get the final solution of pipelines, boundary conditions of pipeline is required.Here, the boundary conditions are simplified to springs along six freedoms. Using the method,all the pipelines with classical constraints can be easily calculated by simply setting thestiffness of the restraining springs from zero to infinite, for example fixed supported, simplysupported, freely supported and elastically supported pipelines.The transfer matrix models of pipeline components, as straight and curved pipeline,L-shaped pipeline, branch pipeline (one branch point and multi-branch point inclueded) andtaper pipeline are established. Here, the joint condition between pipeline sections can bearbitrary. Through balance of displacement and force of branch point, the transfer matrixmodel for branch pipeline with one branch point is also obtained. Combined with boundaryconditions, the solution equation for it is got. Base on these, through complex matrixtransformation, the transfer matrix model for branch pipeline with more branch points isobtained. The solution equation is also gained with boundary condition. For taper pipeline, by divided into N sections, and any section equivalent with straight pipeline, the transfer matrixmodel of taper pipeline is set up.There exist many flanges, clamps, valves and pumps in pipeline systems, which canaffect the dynamic behavior of pipeline systems. Flanges and clamps, can be simplified intoconvergence mass component, and with theory of mechanics, the transfer matrix of them aregained. But valves and pumps, not only they can increase an added mass on pipelines, butalso they are the excitation of the pipelines. So, using four-channel method and theory ofmechanics, the transfer matrix model of valves and pumps are set up.Based on the results above, with the point transfer matrix and field transfer matrix ofpipeline components and accessories with arbitrary support, the transfer matrix for arbitrarypipeline systems is set up. The solution equation is also obtained combined with boundarycondition, which can be used for any pipeline systems.A testing bed for measuring pipelines is designed and built. By the measurement ofcharacteristic parameters of the response of straight pipeline, Y-shaped pipeline andcross-shaped pipeline under excitation, the correctness of the model and method is validated.And the characteristic of the vibration and noise of pipeline considering fluid-structureinteraction is also analyzed through the measurement data.In the end, the classic pipeline components are calculated and analyzed with differentstructural parameters and types of support. And the characteristic and law of vibration ofpipelines considering fluid-structure interaction is analyzed, which can be used to guide thecontrol of vibration and noise of pipeline and design of low-noise pipeline components.