An extended numerical model for bubbly oil/gas flows, using a more complete formulation than previously reported, is applied to five situations of industrial interest. Pressure waves propagating due to pressure differences caused by the sudden blocking of a pipeline carrying bubbly fluid, the bursting of a valve separating two regions of different pressures, and the opening and closing of a valve in a pipeline are simulated. In addition, the movement of an end plug to a bubbly flow pipeline when it fails is also modelled. In each case it is found that over-pressures, relative to the applied pressure difference, occur in the propagating pressure waves. The magnitude of the over-pressure increases with the applied pressure difference and appears close to, but not at, the boundary where the pressure difference is first applied. However, gradual application of the pressure difference reduces the maximum over-pressure. In the case of the sudden blockage of a pipeline, the over-pressure also varies with the initial flow velocity and has a greater magnitude than the predicted pressure rise calculated using only the fluid compressibility. Therefore, standard estimates for pressure rises in compressible fluids may be inappropriate for use in designing pipelines carrying bubbly fluids. Finally, the end plug simulations show that the plug accelerates quickly after the initial failure but then levels off, and that the final velocity of the end plug can be readily calculated using the numerical model. (C) 2000 Elsevier Science Lad. All rights reserved.
|Number of pages||22|
|Journal||International Journal of Engineering Science|
|Publication status||Published - 2000|
- shock waves
- bubbly fluids
- numerical simulation
- oil/gas industry