Abstract:In first stage, a machine learning (ML) was performed to predict in-cylinder pressure using both fuzzy logic (FL) and artificial neural networks (ANN) depending on the results of experimental studies in a spark ignition (SI) engine. In the ML phase, the experimental in-cylinder pressure data of SI engine was used. SI engine was operated at stoichiometric air–fuel mixture (φ = 1.0) at 1200, 1400, and 1600 rpm engine speeds. Six different ignition timings, ranging from 15 to 45 °CA, were used for each engine spe… Show more
“…Furthermore, to further investigate the accuracy of the developed CFD model, the root mean square ( R 2 ) was used, which is defined by Eq. (40) 48 , 49 . Figure 5 shows the results of comparison between numerical results and experimental data.…”
In this study, the effects of several structural and operational parameters affecting the separation efficiency of supersonic separators were investigated by numerical methods. Different turbulence models were used and their accuracies were evaluated. Based on the error analysis, the V2-f turbulence model was more accurate for describing the high swirling turbulent flow than other investigated turbulence models. Therefore, the V2-f turbulence model and particle tracing model were selected to optimize the structure of the convergence part, the diffuser, the drainage port, and the swirler. The cooling performance of three line-type in the convergent section were calculated. The simulation results demonstrated that the convergent section designed by the Witoszynski curve had higher cooling depth compared to the Bi-cubic and Quintic curves. Furthermore, the expansion angle of 2° resulted in the highest stability of fluid flow and therefore was selected in the design of the diffuser. The effect of incorporating the swirler and its structure on the separation performance of supersonic separator was also studied. Three different swirler types, including axial, wall-mounted, and helical, were investigated. It was observed that installing the swirler significantly improved the separation efficiency of the supersonic separator. In addition, the simulation results demonstrated that the separation efficiency was higher for the axial swirler compared to the wall-mounted and helical swirlers. Therefore, for the improved nozzle, the swirling flow was generated by the axial swirler. The optimized axial swirler was constructed from 12 arced vanes each of which had a swirl angle of 40°. For the optimized structure, the effects of operating parameters such as inlet temperature, pressure recovery ratio, density, and droplet size was also investigated. It was concluded that increasing the droplet size and density significantly improved the separation efficiency of the supersonic separator. For hydrocarbon droplets, the separation efficiency improved from 4.6 to 76.7% upon increasing the droplet size from 0.1 to 2 µm.
“…Furthermore, to further investigate the accuracy of the developed CFD model, the root mean square ( R 2 ) was used, which is defined by Eq. (40) 48 , 49 . Figure 5 shows the results of comparison between numerical results and experimental data.…”
In this study, the effects of several structural and operational parameters affecting the separation efficiency of supersonic separators were investigated by numerical methods. Different turbulence models were used and their accuracies were evaluated. Based on the error analysis, the V2-f turbulence model was more accurate for describing the high swirling turbulent flow than other investigated turbulence models. Therefore, the V2-f turbulence model and particle tracing model were selected to optimize the structure of the convergence part, the diffuser, the drainage port, and the swirler. The cooling performance of three line-type in the convergent section were calculated. The simulation results demonstrated that the convergent section designed by the Witoszynski curve had higher cooling depth compared to the Bi-cubic and Quintic curves. Furthermore, the expansion angle of 2° resulted in the highest stability of fluid flow and therefore was selected in the design of the diffuser. The effect of incorporating the swirler and its structure on the separation performance of supersonic separator was also studied. Three different swirler types, including axial, wall-mounted, and helical, were investigated. It was observed that installing the swirler significantly improved the separation efficiency of the supersonic separator. In addition, the simulation results demonstrated that the separation efficiency was higher for the axial swirler compared to the wall-mounted and helical swirlers. Therefore, for the improved nozzle, the swirling flow was generated by the axial swirler. The optimized axial swirler was constructed from 12 arced vanes each of which had a swirl angle of 40°. For the optimized structure, the effects of operating parameters such as inlet temperature, pressure recovery ratio, density, and droplet size was also investigated. It was concluded that increasing the droplet size and density significantly improved the separation efficiency of the supersonic separator. For hydrocarbon droplets, the separation efficiency improved from 4.6 to 76.7% upon increasing the droplet size from 0.1 to 2 µm.
“…To compare the numerical and experimental results, the root-mean-square (R 2 ) is employed to determine the error between them [43][44][45], which is defined in Eq. (7).…”
The supersonic separation offers an opportunity for natural gas processing.The problem is that the phase change of water vapour in the supersonic flow is not fully understood in the presence of shock waves in a supersonic separator. This study aims to evaluate the performance of the supersonic separation with the phase change process and shock waves. The condensing flow model is developed to accurately predict the energy conversion within the supersonic separator. The computational results show that the single-phase flow model over-estimates the vapour expansions by 12.43% higher Mach number than the condensing flow model. The liquid fraction of 8.2% is predicted by the condensing flow model during the phase change process in supersonic separators.The supersonic separator is optimised via combining the diverging part of the supersonic nozzle and constant cyclonic separation tube as a long diverging part of the newly designed nozzle. The optimised supersonic separator reduces the energy loss by eliminating the oblique and expansion waves in the newly designed nozzle, which 2 improves the energy efficiency for natural gas processing.
“…The root-mean-square (R 2 ), which is defined in Eq. ( 7), is used to compare the numerical and experimental errors [44][45][46]. Figure 4 shows the computed and experimental pressure and droplet radius, as well as the relative errors.…”
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