دراسة تجريبية وعددية لجريان ثنائي الطور في قناة توسعية مستطيله مضلعة

Rp_EXPERIMENTAL AND NUMERICAL STUDY OF TWO- PHASE FLOW IN THE RIBBED DIVERGENT RECTANGULAR DUCTS pdf

Two-phase flow in the ribbed divergent\convergent rectangular duct for two cases: upward vertical and inclined were studied in this thesis. The materials used for two-phase, water and air were used. Experimental and numerical studies have been performed to test the influence of increased air and water discharges on the pressure profile and difference pressure through the divergent\convergent section, As the effect of increasing the divergent/ convergent angle on the pressure difference across the divergent/convergent section was studied.
The characterizations of flow patterns are achieved via visual observation. A pressure sensor with interphase and video camera recording were used to study flow regimes through the test channel. Water inlet discharges used were between (5-20 L/min), and air discharges were between (5.833-16.666 L/min). Two test channels with divergent\convergent angles (10 and 15 degrees) were used.
An experimental rig was constructed with dimensions were (2 * 6) cm of the cross-section area before the divergent\convergent section with length were 50 cm long, while the section area was (2 * 8) cm after the divergent\convergent section with length were 50 cm too.
Computational fluid dynamics for a three-dimensional model was simulated with ANSYS fluent 18 depending on the boundary condition obtained experimentally and governed by equations of Eulerian multiphase flow model.
A agree was observed between the experimental and numerical values of pressure with maximum deviation was 9 %, as a similarity was observed in the flow behavior between experimental and numerical work.
The results indicated that the pressure along the test channel raises as water and air discharge rise. for vertical test channel with divergent section (10 degree) , as the water discharge increased from (5 L/min to 20 L/min) at the same location of the pressure transducer and constant air discharge (35 cm and 5.833 L/min), respectively, the value of pressure increase from (14.6 kpa to 16.7 kpa ).
For the divergent section, It was observed that as the divergence opening angle increases, the pressure recovery decreases. While in the case of the convergence section, the pressure drop increases with the increase of the convergence angle.
It was observed that the dominant flow pattern within the range of discharges used was a slug flow pattern. The values of air and water discharges were represented on the Hewitt and Roberts flow maps (1969) for vertical flow, as the Barnea flow map (1980) was used for inclined flow. A good agreement was observed between the type of flow that appeared in the experiments and the flow maps.
A numerical study only was conducted to study the effect of the ribs on flow behavior and pressure recovery, It was noted that the value of the recovery of the pressure across the divergence section of the absence of ribs is higher than the case of presence ribs by 8.333%.