Numerical Analysis Of Underwater Suspended Pipe With Axial Crack Flaw

In water, pipeline is possibility washed out to be suspended span. Because pipeline's suspended span does not have the soil support, it is easy to vibrate under the vortex's function. When existed axial crack flaw in pipe, coupled with fatigue failure caused by the vortex, its bearing pressure ability will drop. In the service the pipeline will lead to a sudden failure. It will affect the normal production , bring the environmental pollution and causing huge losses to the national economy.In this paper, numerical simulation of water flow around a suspended pipe is done. The suspended pipe with axial crack flaw has many kinds of load joint action. Using the results, pipe's defects stress analysis, internal pressure analysis and fatigue life are studied. This paper main research content includes:1,Flow characteristic and theory around pipeIn a certain velocity, relief frequency eddy behind the suspended pipe could be close to the natural frequency channels. Thus similar resonance effect vertical to the flow appears. It leads the vibration along the flow direction and drag increase. Two directions of vibration could be produce great alternating stress, which causes the pipeline to have the fatigue failure.2,Numerical analysis of water flow around pipe under high reynold numberAccording to hydromechanics and computation hydromechanics theory, numerical analysis of flow around a pipe under high reynold number is studied. Lift and drag coefficients are monitored, and eddy contours of the distribution, pressure distribution, shear stress distribution are analyzed.3,Numerical analysis of viscous flow around a suspended pipe resonant transversely in a uniform streamThe fatigue failure of transverse vortex-induced vibration is far greater than the downstream. Therefore, in order to avoid the transverse vortex-induced vibration, lift coefficient, drag coefficient, vortex contours of the distribution and power spectrum of lift coefficient under the different frequency ratios are calculated. When"frequency-locking phenomenon"occurrences, control of suspended pipe's vacant length is calculated.4,Numerical simulation of pipe with axial crack flaw underwaterComputation model of suspended pipe is established. The suspended pipe with axial crack flaw has many kinds of joint loads and different support conditions. Pipe's defects stress analysis and fatigue life is analyzed.