Theoretical and experimental research of two-and multiphase flow in channels, closed conduits and reactors, including a description of the solid-particle motions, is the basis of many industrial processes and engineering disciplines, such as mixing and handling of multiphase mixtures or systems or hydraulic transport of slurries.
In the Institute of Hydrodynamics CAS, v. v. i., the research on two-phase flows is focused on the study of fine-grained, coarse-grained and complex slurries. In particular, on the effect of pipe size and inclination, and the physical parameters of the suspension to the energy losses, concentration distribution and velocity of both phases in a flowing mixture, the study of particle motion in the flow with fixed or movable bed in order to optimize the flow, determine the effect of particle size distribution, mechanical treatment and the physical-chemical environment of the suspension on the mutual dependence of the pressure gradient, velocity and concentration. Further mathematical modeling and numerical simulation of particle and cloud of particles motion in different flow conditions, calibration and verification of flow models based on the results of experimental research.
Pipeline transport is mainly used for transporting of large quantities of bulk materials in the energy, mining and construction industries (minerals, ores, concentrates, sand and gravel) or for the transport of wastes (municipal, industrial and construction waste, tailings). To assess pipeline transport it is important effect of physical parameters of both carried and carrier phases to the optimum flow rate and the dependence of energy losses during transport to the velocity and concentration of entrained phase, inclination, diameter and roughness of the pipe and the flow pattern.
- Flow of fine-grained (homogeneous, non-settling) slurries (e.g. Kaolin, clay, fly ash) in pipe. Laminar, turbulent and transitional flow regime. Rheological models. The effect of concentration on flow behaviour. Effect of mechanical treatment, shear stress, chemical additives of flow behaviour.
- Flow of coarse-grained (heterogeneous, settling) slurries (e.g. sand, glass beads, bottom ash, gravel) in pipe. Effect of concentration and particle size distribution on flow behaviour in horizontal, inclined and vertical pipe sections. Local concentration, chord-averaged concentration profiles, and concentration maps measurement. Flow models. Investigations of concentration distribution, particle and carrier liquid velocity, pressure gradient, deposition limit velocity, slip velocity.
- Flow of complex slurries (solid materials including fine and coarse particles) in pipe. Effect of concentration and particle size distribution on the flow behaviour in horizontal, inclined and vertical pipe sections. Investigations of concentration distribution, pressure gradient, deposition limit velocity. Effect of fine/coarse particles addition on slurry flow behaviour of coarse/fine-grained slurries.
- Stratified flows, i.e. flows with stationary and sliding beds, slurry inner structure, transport layer behaviour, roughness and erosion of bed layer, flow conditions at layer interfaces. Predictive models for the friction loss and distribution of solids concentration.
- Hydraulic capsule flow in pipeline. Effect of density, length and diameter ratio, capsule shape and rigidity, pipe inclination and additives on velocity ratio and pressure drops correlation.