The transportation of high viscous oil surrounded by a water layer is one of the energy efficient technologies. In this study, the VOF, standard k−ε, and CSS models are performed to simulate the oil−water core annular flow across a Π bend, and the tendency of phase contour and phase fraction simulated appears reasonably consistent with the photo from experiments and the empirical correlation. The effects of input water fraction, the flow direction, the oil property, and the geometric parameters (include aspect ratio, diameter ratio, fillet radius, and roughness) on hydrodynamic performance and fouling characteristics are analyzed, and the results could provide a reference for designing the pipeline and optimizing operation conditions and the Π bend structures.
The oil‐water core annular flow through a U‐bend is simulated by computational fluid dynamics based on the Eulerian model. More flow parameters and the effect of annulus thickness on core annular flow are discussed. Conformity between the simulated and experimental data is observed. The development of oil‐water core annular flow in the U‐bend is analyzed, and the distributions of pressure and velocity are discussed. Results of the Eulerian model and volume‐of‐fluid (VOF) model are compared and the influence of oil properties on total pressure gradient is investigated. The suitable range of annulus thickness is identified. The results provide suitable operation conditions for designing the U‐bend pipefitting.
Control for the HEV propulsion system based on dynamic processes is proposed. Parameters of the controller are optimized in order to optimize the dynamic characteristics. For the purpose of solving the problem that the energy consumption will increase while the dynamic characteristics are optimized, fuzzy control is put forward for the HEV. The dynamic characteristic is than improved, and the output required from the engine and motor will not go beyond their ability, which allows the optimized target of the control strategy to be implemented.
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