الفهرس | Only 14 pages are availabe for public view |
Abstract The study presents in details, experimental and numerical studies on emulsion (oil-in-water) flow in rectangular cross-sectional area S-shaped diffusers. The experimental setup was designed and constructed in the fluid mechanics laboratory of the faculty of engineering, Menoufia University to obtain the experimental data since the measurements have been performed on twelve S-shaped diffusers. Different parameters including area ratio, curvature ratio, turning angle (45◦/45◦, 60◦/60◦, and 90◦/90◦), flow path (45◦/45◦, 60◦/30◦, and 30◦/60◦), inflow Reynolds number, holdup (0.03, 0.06, 0.10, 0.15, and 0.25) and emulsion stability have been considered. The static pressure distributions along the outer and inner walls of the S-diffuser including upstream and downstream tangents were measured. Based on these measurements, the energy-loss coefficient of all models could be extracted. The diffusers performance has been plotted versus inflow Reynolds number at different geometrical and inflow parameters. The studies were carried out using two types of oil-in-water (o/w) emulsions; stable o/w emulsion by using an emulsifier named by Sodium Dodecyl Sulfate (SDS) and unstable o/w emulsion without any additives at different holdup values. The experimental data for different S-diffuser configurations have been used for assessing credibility of the numerical code using ANSYS R-15.0 software Fluid Flow Fluent (FFF) - 3D with different solution methods. Computations with different turbulence closures have been carried out for prediction of the performance of S-shaped diffusers at different inflow and geometrical conditions in case of water as well as emulsion flows. With emulsion flow, besides the standard k-ε model, the mixture model was used The study presents in details, experimental and numerical studies on emulsion (oil-in-water) flow in rectangular cross-sectional area S-shaped diffusers. The experimental setup was designed and constructed in the fluid mechanics laboratory of the faculty of engineering, Menoufia University to obtain the experimental data since the measurements have been performed on twelve S-shaped diffusers. Different parameters including area ratio, curvature ratio, turning angle (45◦/45◦, 60◦/60◦, and 90◦/90◦), flow path (45◦/45◦, 60◦/30◦, and 30◦/60◦), inflow Reynolds number, holdup (0.03, 0.06, 0.10, 0.15, and 0.25) and emulsion stability have been considered. The static pressure distributions along the outer and inner walls of the S-diffuser including upstream and downstream tangents were measured. Based on these measurements, the energy-loss coefficient of all models could be extracted. The diffusers performance has been plotted versus inflow Reynolds number at different geometrical and inflow parameters. The studies were carried out using two types of oil-in-water (o/w) emulsions; stable o/w emulsion by using an emulsifier named by Sodium Dodecyl Sulfate (SDS) and unstable o/w emulsion without any additives at different holdup values. The experimental data for different S-diffuser configurations have been used for assessing credibility of the numerical code using ANSYS R-15.0 software Fluid Flow Fluent (FFF) - 3D with different solution methods. Computations with different turbulence closures have been carried out for prediction of the performance of S-shaped diffusers at different inflow and geometrical conditions in case of water as well as emulsion flows. With emulsion flow, besides the standard k-ε model, the mixture model was used as a solution multi-phase model using fine grid to obtain a more accurate flow prediction. The continuous phase (water) has been simulated using standard k-ε model by solving Reynolds-Averaged Navier-Stokes equations (RANS), while the dispersed phase (oil) has been simulated using mixture multi-phase model by solving oil liquid particle equations using 4th order Runge-Kutta method. Comparisons between present CFD code predictions and available experimental results from literature as well as the present experimental data showed good matching and better agreement. The results showed that the S-shaped diffuser energy-loss coefficient is strongly affected by the geometrical and inflow parameters. Increasing area ratio, curvature ratio, and inflow Reynolds number leads to improving diffuser performance. Whereas, decreasing the emulsion holdup (Φ) leads to decreasing diffuser performance. The turning angle plays an important role in improving the S-shaped diffuser performance. S-shaped diffuser energy-loss coefficient of water flow is lower than that of emulsion flow. Also the S-shaped diffuser energy-loss coefficient of stable o/w emulsion flow is higher than that of unstable, one. A general new correlation of energy-loss coefficient including geometrical and flow parameters for the validated studied cases of S-diffusers is extracted from the measurements. |