Scaling effects in vertical bubbly pipe flow

On the basis of detailed experimental data obtained for stationary bubbly flow in vertical pipes with an inner diameter of 51.2 mm and 194.1 mm, analytical investigations on scaling effects were made. Because of the interaction between the phases the scaling behavior is very complex in case of two phase flow. Similarity can only be achieved regarding selected parameters. Thus the modeling of scaling effects has to be based on local models for the phase interaction. A simplified model, introduced earlier, is used for the validation of such models by consideration of scaling effects. Because of the strong influence of the bubble size distribution on the flow, the model considers a number of bubble classes. Models for the non-drag forces acting on bubbles were validated for the small pipe and afterwards used for the prediction of radial gas volume profiles in the large pipe. The comparison with measured profiles shows that there is a generality of these models. Even more complex is the situation regarding the development of the flow along the pipe. Here bubble coalescence and break-up are important. There is still a need for an improvement of these models.