Rotational flow occurs in nature as well as in many industrial fields (e.g power plants, chemical plants, oil and gas industries, etc) and often involving multi-phase. A detailed understanding of the flow characteristics is required for the design and optimization of industrial devices and processes as well as for safety considerations of multi-phase flow systems. Computational Fluid Dynamics (CFD) can be used to provide such detailed information.
In the case of gas-liquid rotating flows, there are situations in which different morphologies of gas are present simultaneously. As an addition the transition can also be occurred between the gas structures. To accommodate such flows, an innovative concept nameled GENTOP (Generalize Two Phase Flow) combining two modelling frames, iMUSIG and AIAD, has been developed in HZDR.
Here the use of GENTOP Concept is demonstrated for simulating two different flow situations. The first case is the investigation of gas-liquid flow around a swirl generating device. The swirl element is used to generate centrifugal force for separation process. The streamlines of liquid and dispersed gas velocities presented in Fig. 1 describe the change of the flow situation from straight flow into swirling flow downstream the element. That change leads to the accumulation of gas phase in the center of the pipe (see Fig. 2). The simulation demonstrates that GENTOP Concept can be used to simulate different gas morphologies presents in this inline separator and the transition between them due to the presence of the swirl element.
The second case demonstrates how GENTOP Concept can be used to simulate bubble entrainment driven by free-surface vortex. Here the transition occurs from continuous gas into dispersed gas structures. Fig.3 shows contour of the fraction of potentially continuous gas and dispersed gas in the central longitudinal planes of the test section. By using the entrainment model integrated in the GENTOP Concept, the bubble entrainment can be well considered in the simulation. Those aforementioned simulations prove that GENTOP Concept has a good potential to be used for complex rotational multi-phase flows.