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Modelling of supercritical turbulent flow over an inclined backward-facing step in a open channel
Příhoda, Jaromír ; Zubík, P. ; Šulc, J. ; Sedlář, M.
The contribution deals with the experimental and numerical modelling of supercritical turbulent flow in an open channel with an inclined backward-facing step on its bottom. The step with the height 100 mm and the inclination angle 20 deg was placed in the water channel of the cross-section 200x200 mm. Experiments were carried out by means of the PIV and LDA measuring techniques. Numerical simulations were executed by the commercial software ANSYS CFX 12.0. Numerical results obtained by the two-equation SST model and the EARSM model completed by transport equations for turbulent energy and specific dissipation rate were compared with experimental data. The modelling was concentrated particularly on the flow pattern near the step including the possible flow separation and the corresponding changes of free surface. The agreement of numerical results obtained by means of the EARSM model with experimental data is quite good.
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Experimental and numerical modelling of liquid flow with separation
Zubík, P. ; Šulc, J. ; Příhoda, Jaromír ; Sedlář, M.
The contribution deals with the experimental and numerical modelling of turbulent pressure, subcritical and supercritical flow with massive separation due to sudden expansion of the cross section (flow over an inclined step). Experiments were carried out in the water channel with the cross-section 200x200 mm by means of PIV and LDA measuring methods. Numerical simulation was carried out using the VOF (Volume-of-Fluid) method by means of the commercial software ANSYS CFX-12.0. Numerical results were compared with experimental data.
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Modelling of subcritical free-surface flow over an inclined backward-facing step in a water channel
Příhoda, Jaromír ; Zubík, P. ; Šulc, J. ; Sedlář, M.
The contribution deals with the experimental and numerical modelling of subcritical turbulent flow in an open channel with an inclined backward-facing step. The step with the inclination angle 20 deg was placed in the water channel of the cross-section 200x200 mm. Experiments were carried out by means of the PIV and LDA measuring techniques. Numerical simulations were executed by means of the commercial software ANSYS CFX 12.0. Numerical results obtained for two-equation models and EARSM turbulence model completed by transport equations for turbulent energy and specific dissipation rate were compared with experimental data. The modelling was concentrated particularly on the development of the flow separation and on the corresponding changes of free surface.
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Renewable Source of Energy – Gasification of Biomass with Co-generation of Heat and Electricity
Šulc, J. ; Richter, M. ; Svoboda, Karel ; Vacek, J.
Co-generation processes based on combined production of heat and electricity from biomass will be preferred. Biomass gasification (mainly woody biomass), even in a smaller scale, offers relatively high efficiency of power generation, higher than commonly attained in combustion processes. Gasification of biomass produces raw fuel gas, which can be used, after appropriate cleaning, as a fuel in internal combustion engine or (after compression) gas turbine. The gasifier is based on co-current flow of gas and solid phase, up-flowing biomass (wood pellets) driven by a vertical screw and gasification by air. The gas cleaning is based on separation of dust, oil and water scrubbing for Removal of tar, soot, organics and ammonia. Electricity will be produced from the clean fuel gas by means of a gas engine and power(electricity) generator.
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Modelování nadkritického obtékání prahů na dně otevřeného kanálu
Příhoda, Jaromír ; Šulc, J. ; Zubík, P. ; Sedlář, M.
The contribution deals with the experimental and numerical modelling of turbulent supercritical flow over one or two bed sills of the cross-section 3030 mm placed in an open channel. Experiments were carried out in the water channel with the cross-section 200200 mm by means of PIV and LDA measuring methods. Optical methods were completed by the measurement of pressure distribution on rib surface in the channel centreline. Numerical simulation was carried out using the VOF method by means of the commercial software ANSYS CFX-11.0. Numerical results obtained for various two-equation turbulence models were compared with experimental data. The effect of the sill spacing on the extent of the separation region, the deformation of free surface and on the drag of individual sills was primarily investigated.
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Vyšetřování turbulentního proudění v otevřeném kanálu s příčnými prahy
Příhoda, Jaromír ; Šulc, J. ; Sedlář, M. ; Zubík, P.
The contribution deals with the experimental and numerical modelling of turbulent supercritical flow over one and/or two transversal ribs with the cross-section 30x30 mm placed at the bottom of an open channel. Numerical simulation was carried out using the VOF (Volume-of-Fluid) method by means of the commercial software ANSYS CFX-11.0 for supercritical flow characterised by the Froudé number Fr = 2.2. The effect of the rib spacing on the extent of the separation region, the deformation of free surface and on the drag of individual ribs was primarily investigated. Numerical results were compared with experiments accomplished in the water channel with the cross-section 200x200 mm by means of PIV and LDA measuring methods. Optical methods were completed by the measurement of pressure distribution on rib surface in the channel centreline.
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Experimentální a numerické modelování turbulentního obtékání příčných prahů v otevřeném kanálu
Příhoda, Jaromír ; Šulc, J. ; Sedlář, M. ; Zubík, P.
Modelling of turbulent flow in an open channel with transversal ribs on its bottom was concentrated particularly on the development of flow separation behind ribs and on the corresponding changes of free surface. Further, the pressure drag of individual ribs was investigated including their dependence on the rib spacing, as well as the origin of secondary flow near the side walls of the channel behind ribs. Numerical results obtained by the software ANSYS CFX 11.0 were compared with experiments carried out by means of LDA and PIV techniques in free-surface water channel 200x200 mm with one and/or two transversal ribs 10xl0 mm with various spacing.
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