Two Dimensional Numerical S Of Flow Over The Pipeline With Fins And VIV Of The Pipeline With Fins

With an increasing human demand for marine energy, the submarine pipelines have got unprecedented development in the exploration of offshore fields, and the research on submarine pipeline has also made great progress. During the decades, domestic and foreign scholars have done a lot of research on the bare pipeline, however, only a little study about the effective measures to suppress response amplitude of submarine pipeline in an unfavorable marine environment. The spoiler attachments are usually applied in practice; however, suppression mechanism of spoilers is not completely understood. It is necessary and urgent to carry out the study about the flow around the pipeline with the spoilers and the vortex-induced vibration of the pipeline with the spoilers.Two-dimensional incompressible flow around submarine pipeline with spoilers was investigated numerically. The Reynolds-averaged Navier-Stokes equations were solved by using finite volume method with the RNG k-s turbulence model. The effect of the different gap ratio and the different height for the cylinders with four kinds of spoilers were compared and analyzed respectively by the vortex model, lift coefficients, drag coefficients and St. The numerical results indicate that the separation point can be controlled by the four kinds of spoilers effectively. At the same height of spoilers, the effect of controlling vortex for different spoilers is concerned with the gap ratio. The effectiveness of the A30and A00spoilers in suppressing vortex shedding is predominantly affected when the gap ratio is0.3. The spoiler has a better result and force condition when the gap ratio is smaller; especially the A60spoiler is most effective. And the lift coefficient and drag coefficient of pipelines increase as the increasing height ratio in the same gap ratio.To found the effect of the spoiler on the pipeline vibration, two-dimensional fluid-structure numerical investigation of pipeline had been conducted by applying the standard k-e turbulence model and mass-spring system simplification. A hybrid grid method, Arbitrary Lagrangian Eulerian (ALE) method and leader-follower method were used together in these numerical simulations, availably keeping good quality of the fluid domain mesh for large displacements of fluid-structure interface.Firstly, the "beat","phase switch" and "locked-in" phenomena were successfully captured by simulating the vortex induced vibration of bare pipeline, and the results agreed well with available experimental and numerical results of previous scholars, then the accuracy of the model was proved. Secondly, the vortex induced vibration for A60pipeline was numerically simulated. Vortex shedding mode, vibration response, vibration frequency, and force were analyzed for A60pipeline, and compared with bare pipeline. Lastly, the vibration response and lift coefficients were compared for the pipeline with A60spoiler at two different heights (0.2D and0.3D).The numerical results show that the A60spoiler can affects the vortex shedding and synchronization by reducing the lateral spacing of the initial large eddy. Meanwhile, the vibration amplitude and the resonance region of the pipeline with A60spoiler are smaller than the bare one throughout the reduced velocity range. Compared with the0.2D height of the A60spoiler, the0.3D height of the A60spoiler had no more effect on suppressing vibration.