[en] The proceedings include the comparison of experimental results with predictions obtained by several groups involved in the numerical treatment of particulate two-phase flows. The numerical predictions were based on three sets of experimental data taken from the literature and measured at the Lehrstuhl fuer Stroemungsmechanik of Erlangen University. The aim of the workshops is to improve the numerical prediction procedures and the modelling of two-phase flow, mainly concerning the interaction of the dispersed phase with a turbulent flow field. To a great extent this could be accomplished during the last workshops. However, there are still problems to be solved for improving the modelling of two-phase flows and to make the numerical codes more efficient in order to allow the calculation of more complex flow fields within a reasonable computation time. (orig./GL)

[en] In the following, we want to present a project at KfK, which is concerned with experimental research on the mechanics of phase transport and resulting spatial phase distributions in bubbly two-phase flow in order to understand basic physical bubble transport phenomena. Within this project, adiabatic air-water bubble flows in vertical tubular channels are investigated. For upward and downward directed bubble flows, local flow properties are investigated experimentally. On the base of the experimental data, models are developed for the numerical simulation of bubble transport and distribution processes in vertical channels. Hereby, the turbulence structure in the continuous phase as well as the interfacial interaction forces (e.g. transverse lift forces) seem to be of special significance. (orig./GL)

[en] The mathematical model used in these two-phase flow predictions consists of an Eularian fluid flow model and a Lagrangian particle flow model. It can handle turbulent particulate flows with or without swirl in plane or axisymmetric geometries. (orig./GL)

[en] Double pulse holography is a very valuable means of measuring the transport processes in disperse phases. This paper initially describes the basic process of holographic imaging and evaluation of the data of the disperse phase in two-phase pipe flows. With the aid of a few examples, the variety of different results are to be portrayed. (orig.)

[en] The vertical motion of a rigid sphere in a quiescent viscous fluid towards a horizontal plane wall is analized by a simplified equation of motion, which takes into account as the only wall correction that to the Stokes drag force. The phase space analysis for this equation is sketched; it has been motivated by measurements performed at the LSTM-Erlangen. A more detailed exposition is given in the Erlangen report LSTM 222/T/87. (orig.)

[en] The particle dispersion of a particle material having a large standard deviation in the size distribution was experimentally studied by the application of a phase-Doppler system. The flow configuration considered was a vertical plane confined turbulent jet flow. In this flow field the gas and particle velocity and number density was measured in several planes above the inlet using a phase-Doppler system. This measuring technique additionally enables particle size measurements so that the particle size and their velocity may be correlated. The mean velocity of these different sized particles was found to be about the same. The turbulent fluctuations however, showed a relative wide spectrum, where the larger particles had the lower turbulence intensity. Furthermore the spatial change of the particle size distribution throughout the flow field would be obtained and discussed. (orig.)

[en] There is still a lack in the knowledge about many physical processes in two-phase flows and therefore their mathematical description for the modelling of two-phase flows by computer simulations still needs some improvement. One required information is the physical procedure of the momentum transfer between the phases themselves, such as particle-particle or particle-fluid interactions, and between the phases and the flow boundaries, such as particle-wall or fluid-wall interactions. The interaction between the two phases can be either a 'long-range' interference or a direct contact between both. For the particle-fluid two-phase flow system the interaction can be devided in particle-fluid, particle-particle and particle-boundary interactions. In this investigation the attention is drawn to the special case of a particle-wall interaction and its 'long-range' interference effect between the wall and a small particle which approaches the wall in normal direction. (orig./GL)

[en] To avoid turbulence predictions discrepancies to be echoed in the particle dispersion processes, some of the test cases have been carried out with given experimental data, for turbulence quantities. That leads us to validate the particle dispersion modules only. (orig.)

[en] Additional problems for the treatment of heavy particle dispersion arise from the effect of crossing trajectories. This effect is caused by an external potential force field acting on the particle and producing the drift velocity between the particle and the fluid. As a result particle crosses the fluid turbulence eddies and loses velocity correlation more rapidly than a fluid point. The heavy particle integral time scale and consequently the dispersion coefficient decreases. Similar effect arises in nonhomogeneous flows when particle migrates from regions of different velocities, but in that case the problem is even more complex because of the different particle velocity fluctuations in two regions. The aim of this study was to demonstrate these effects in experimentally investigated dispersion situations of Snyder and Lumley (1971), Wells and Stock (1983) and Arnason (1982) by means of a comparison with a recently developed Lagrangian Stochastic-Deterministic (LSD) model (see Milojevic, 1986). The LSD model is stochastic in the sense that the 'instantaneous' fluid velocity field is generated from known turbulence energy and time scales of large eddies by using a random sampling. (orig./GL)

[en] A modified version of a numerical scheme which is suitable to predict parabolic dispersed two-phase flow, is presented. The original version of this scheme was used to predict the test cases discussed during the 3rd workshop on TPF predictions in Belgrade, 1986. In this paper, two particle dispersion models are included which use the Lagrangian approach predicting test case 1 and 3 of the 4th workshop. For the prediction of test case 1 the Lagrangian Stochastic Deterministic model (LSD) is used providing acceptable good results of mean and turbulent quantities for both solid and gas phases; however, the computed void fraction distribution is not in agreement with the measurements at locations away from the inlet, especially near the walls. Test case 3 is predicted using both the LSD and the Stochastic Separated Flow (SSF) models. It was found that the effects of turbulence modulation are large when the LSD model is used, whereas the particles have a negligible influence on the continuous phase if the SSF model is utilized for the computations. Predictions of gas phase properties based on both models agree well with measurements; however, the agreement between calculated and measured solid phase properties is less satisfactory. (orig.)