The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull for...The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions （12 kn and 16 kn）. The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization.展开更多
The worldwide proven recoverable reserves of conventional oil are less than the amount of the heavy oil.Owing to weakly consolidated formation,sand production is an important problem encountered during oil production ...The worldwide proven recoverable reserves of conventional oil are less than the amount of the heavy oil.Owing to weakly consolidated formation,sand production is an important problem encountered during oil production in heavy oil reservoirs,for which frac-pack technique is one of the most common treatments.Hence,how to obtain the optimal fracture geometry is the key to increasing well production and preventing sand.Due to the faultiness that current optimization of the fracture geometry only depends on well productivity,fracture-flow fraction was used to describe the contribution of the fracture collecting and conducting fluids from the reservoir.The higher the fracture-flow fraction,the more likely bilinear flow pattern occurs,thus leading to smaller flow resistance and better results in oil productivity and sand prevention.A reservoir numerical simulation model was established to simulate the long-term production dynamic of a fractured well in rectangular drainage areas.In order to reach the aim of increasing productivity meanwhile preventing sand,a new method based on Unified Fracture Design was developed to optimize the fracture geometry.For a specific reservoir and a certain amount of proppant injected to the target layer,there exits an optimal dimensionless fracture conductivity which corresponds to the maximum fracture-flow fraction,accordingly we can get the optimal fracture geometry.The formulas of the optimal fracture geometry were presented on square drainage area conditions,which are very convenient to apply.Equivalent Proppant Number was used to eliminate the impact of aspect ratios of rectangular drainage area,then,the same method to optimize the fracture geometry as mentioned for square drainage areas could be adopted too.展开更多
Improving the carrying ability of oil film between slipper and swash plate and reducing the partial abrasion of slipper are important to improve the service life and reliability of axial piston pump.In this paper,a nu...Improving the carrying ability of oil film between slipper and swash plate and reducing the partial abrasion of slipper are important to improve the service life and reliability of axial piston pump.In this paper,a numerical simulation model was developed for slipper/swash-plate friction pair based on the elastohydrodynamic theory.The dynamic micro-motion and pressure distribution of slipper were analyzed and it was pointed out that the tilt of slipper was the main reason for its partial abrasion.The simulations about the slippers with different slopes on the outer edge of the sealing belt showed that the partial abrasion could reduce the carrying ability and increase the leakage of the slipper/swash-plate pair.The proper slope on the inner edge helped to improve the carrying ability and reduce the leakage of slipper.The experimental tests were in accord with the simulation results to a great extent,showing that the simulation model had a high accuracy and could be applied to the design and optimization of slipper,and that the slipper with optimal inner slope provided an encouraging method to improve the efficiency and reliability of axial piston pump.展开更多
The effects of the number of significant figures （NSF） in the interpolation polynomial coefficients （IPCs） of the weighted sum of gray gases model （WSGM） on results of numerical investigations and WSGM optimizat...The effects of the number of significant figures （NSF） in the interpolation polynomial coefficients （IPCs） of the weighted sum of gray gases model （WSGM） on results of numerical investigations and WSGM optimization were investigated. The investigation was conducted using numerical simulations of the processes inside a pulverized coal-fired furnace. The radiative properties of the gas phase were determined using the simple gray gas model （SG）, two-term WSGM （W2）, and three-term WSGM （W3）. Ten sets of the IPCs with the same NSF were formcd for every weighting coefficient in both W2 and W3. The average and maximal relative difference values of the flame temperatures, wall temperatures, and wall heat fluxes were determined. The investigation showed that the results of numerical investigations were affected by the NSF unless it exceeded certain value. The increase in the NSF did not necessarily lead to WSGM optimization. The combination of the NSF （CNSF） was the necessary requirement for WSGM optimization.展开更多
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant Nos.l1072154, 51379125）, the National Key Basic Research Development Plan （973 Plan） Project of China （Grant No.2013CB036103）, the High Technology of Marine Research Project of the Ministry of Industry and Information Technology of China and the Program for Professor of Special Appointment （Eastern Scholar） at Shanghai Institutions of Higher Learning （Grant No. 2013022）.
文摘The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions （12 kn and 16 kn）. The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization.
基金supported by the National Science and Technology Major Projects of China (Grant No. 2008ZX05024-03-003-004)
文摘The worldwide proven recoverable reserves of conventional oil are less than the amount of the heavy oil.Owing to weakly consolidated formation,sand production is an important problem encountered during oil production in heavy oil reservoirs,for which frac-pack technique is one of the most common treatments.Hence,how to obtain the optimal fracture geometry is the key to increasing well production and preventing sand.Due to the faultiness that current optimization of the fracture geometry only depends on well productivity,fracture-flow fraction was used to describe the contribution of the fracture collecting and conducting fluids from the reservoir.The higher the fracture-flow fraction,the more likely bilinear flow pattern occurs,thus leading to smaller flow resistance and better results in oil productivity and sand prevention.A reservoir numerical simulation model was established to simulate the long-term production dynamic of a fractured well in rectangular drainage areas.In order to reach the aim of increasing productivity meanwhile preventing sand,a new method based on Unified Fracture Design was developed to optimize the fracture geometry.For a specific reservoir and a certain amount of proppant injected to the target layer,there exits an optimal dimensionless fracture conductivity which corresponds to the maximum fracture-flow fraction,accordingly we can get the optimal fracture geometry.The formulas of the optimal fracture geometry were presented on square drainage area conditions,which are very convenient to apply.Equivalent Proppant Number was used to eliminate the impact of aspect ratios of rectangular drainage area,then,the same method to optimize the fracture geometry as mentioned for square drainage areas could be adopted too.
基金supported by the National Natural Science Foundation of China (Grant No. 51075360)the National Key Technology R&D Program of the Twelfth Five-year Plan of China (Grant No. 2011BAF09B03)the Fundamental Research Funds for the Central Universities
文摘Improving the carrying ability of oil film between slipper and swash plate and reducing the partial abrasion of slipper are important to improve the service life and reliability of axial piston pump.In this paper,a numerical simulation model was developed for slipper/swash-plate friction pair based on the elastohydrodynamic theory.The dynamic micro-motion and pressure distribution of slipper were analyzed and it was pointed out that the tilt of slipper was the main reason for its partial abrasion.The simulations about the slippers with different slopes on the outer edge of the sealing belt showed that the partial abrasion could reduce the carrying ability and increase the leakage of the slipper/swash-plate pair.The proper slope on the inner edge helped to improve the carrying ability and reduce the leakage of slipper.The experimental tests were in accord with the simulation results to a great extent,showing that the simulation model had a high accuracy and could be applied to the design and optimization of slipper,and that the slipper with optimal inner slope provided an encouraging method to improve the efficiency and reliability of axial piston pump.
基金supported by the Ministry of Education,Science and Technological Development of the Republic of Serbia(project No.TR-33018)
文摘The effects of the number of significant figures （NSF） in the interpolation polynomial coefficients （IPCs） of the weighted sum of gray gases model （WSGM） on results of numerical investigations and WSGM optimization were investigated. The investigation was conducted using numerical simulations of the processes inside a pulverized coal-fired furnace. The radiative properties of the gas phase were determined using the simple gray gas model （SG）, two-term WSGM （W2）, and three-term WSGM （W3）. Ten sets of the IPCs with the same NSF were formcd for every weighting coefficient in both W2 and W3. The average and maximal relative difference values of the flame temperatures, wall temperatures, and wall heat fluxes were determined. The investigation showed that the results of numerical investigations were affected by the NSF unless it exceeded certain value. The increase in the NSF did not necessarily lead to WSGM optimization. The combination of the NSF （CNSF） was the necessary requirement for WSGM optimization.
