| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 297511 | Nuclear Engineering and Design | 2011 | 11 Pages |
The current paper presents the prediction results of a bubbly flow under plunging jet conditions using multiphase mono- and poly-dispersed approaches. The models consider interfacial momentum transfer terms arising from drag, lift, and turbulent dispersion force for the different bubble sizes. The turbulence is modeled by an extended k–ɛ model which accounts for bubble induced turbulence. Furthermore in case of a poly-dispersed air–water flow the bubble size distribution, bubble break-up and coalescence processes as well as different gas velocities in dependency on the bubble diameter are taken into account using the Inhomogeneous MUSIG model. This model is a generalized inhomogeneous multiple size group model based on the Eulerian modeling framework which was developed in the framework of a cooperative work between ANSYS-CFX and Forschungszentrum Dresden-Rossendorf (FZD). The latter is now implemented into the CFD code CFX.According to the correlation on the lateral lift force obtained by Tomiyama (1998); this force changes its sign in dependence on the bubble size. Consequently the entrained small bubbles are trapped below the jet. They can escape from the bubble plume only by turbulent fluctuations or by coalescence. If the size of the bubbles generated by coalescence exceeds the size at which the lift force changes its sign these large bubbles go out from the plume and rise to the surface.A turbulent model based on an additional source term for turbulence kinetic energy and turbulence eddy dissipation equation is compared to the common concept for modeling the turbulence quantities proposed by Sato et al. (1981). It has been found that the large bubble distribution is slightly affected by the turbulence modeling which affects particularly the bubble coalescence and break-up process.
► We model a bubbly flow under a plunging jet conditions using multiphase mono- and poly-dispersed approaches. ► We examine the interfacial momentum transfer terms arising from drag, lift, and turbulent dispersion force for the different bubble sizes. ► The models are analysed and compared to each other using some experimental observation. ► It has been found that the large bubble distribution is slightly affected by the turbulence modeling which affects the bubble coalescence and break-up process. ► We can point out an important need for experimental data, particularly the void fraction distribution along the plume to check the accuracy of the models.
