In order to simulate the complicated unsteady flow in Pelton bucket, it is necessary to apply the animated cartoon approach. In this paper, a free jet and the inner surface of a bucket is described by boundary fitted ...In order to simulate the complicated unsteady flow in Pelton bucket, it is necessary to apply the animated cartoon approach. In this paper, a free jet and the inner surface of a bucket is described by boundary fitted grid (BFG) with non-orthogonal curvilinear coordinates. The water flow is discretized in space and time for CFD (computational fluid dynamics). The moving grids of water film are successfully projected onto the bucket’s inner surface by a projection algorithm. The visualization result of the jet landing on bucket’s surface and the unsteady flow in the rotating buckets in 3D verifies the effectiveness of the proposed method.展开更多
When water seeps upwards through a saturated soil layer,the soil layer may become instability and water films occur and develop.Water film serves as a natural sliding surface because of its very small friction.Accordi...When water seeps upwards through a saturated soil layer,the soil layer may become instability and water films occur and develop.Water film serves as a natural sliding surface because of its very small friction.Accordingly,debris flow may happen.To investigate this phenomenon,a pseudothree-phase media is presented first.Then discontinuity method is used to analyze the expansion velocity of water film.Finally,perturbation method is used to analyze the case that a water flow is forced to seep upwards through the soil layer while the movement of the skeleton may be neglected relative to that of water.The theoretical evolutions of pore pressure gradient,effective stress,water velocity,the porosity and the eroded fine grains are obtained.It can be seen clearly that with the erosion and redeposited of fine grains,permeability at some positions in the soil layer becomes smaller and smaller and,the pore pressure gradient becomes bigger and bigger,while the effective stress becomes smaller and smaller.When the effective stress equals zero,e.f.liquefaction,the water film occurs.It is shown also that once a water film occurs,it will be expanded in a speed of U(t)(1-ε).展开更多
The liquid phase turbulent structure of an air-water bubbly horizontal flow in a circular pipe has been investigated experimentally. Three-dimensional measurements were implemented with two "X" type probes o...The liquid phase turbulent structure of an air-water bubbly horizontal flow in a circular pipe has been investigated experimentally. Three-dimensional measurements were implemented with two "X" type probes oriented in different planes, and local liquid-phase velocities and turbulent stresses were simultaneously obtained. Systematic measurements were conducted covering a range of local void fraction from 0 to 11.7%. The important experiment results and parametric trends are summarized and discussed.展开更多
Water quality within water distribution system may vary with both location and time. Water quality models are used to predict the spatial and temporal variation of water quality throughout water system. A model of res...Water quality within water distribution system may vary with both location and time. Water quality models are used to predict the spatial and temporal variation of water quality throughout water system. A model of residual chlorine decay in water pipe has been developed, given the consumption of chlorine in reactions with chemicals in bulk water, bio films on pipe wall, in corrosion process, and the mass transport of chlorine from bulk water to pipe wall. Analytical methods of the flow path from water sources to the observed point and the water age of every observed node were proposed. Model is used to predict the decay of residual chlorine in an actual distribution system. Good agreement between calculated and measured values was obtained.展开更多
Subject code:E02 With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhou Jun(周军)from Wuhan National Laboratory for Optoelectronics,Huazhong U...Subject code:E02 With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhou Jun(周军)from Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Prof.Guo Wanlin(郭万林)from Nanjing University展开更多
A numerical method for the analysis of the electrothermal deicing system for an airfoil is developed taking into account mass and heat exchange at the moving boundary that separates the water film created due to dropl...A numerical method for the analysis of the electrothermal deicing system for an airfoil is developed taking into account mass and heat exchange at the moving boundary that separates the water film created due to droplet impingement and the ice accretion region.The method relies on a Eulerian approach(used to capture droplet dynamics)and an unsteady heat transfer model(specifically conceived for a multilayer electrothermal problem on the basis of the enthalpy theory and a phase-change correction approach).Through application of the continuous boundary condition for temperature and heat flux at the coupled movingboundary,several simulations of ice accretion,melting and shedding,runback water flow and refreezing phenomena during the electrothermal deicing process are conducted.Finally,the results are verified via comparison with experimental data.A rich set of data concerning the dynamic evolution of the distribution of surface temperature,water film height and ice shape is presented and critically discussed.展开更多
文摘In order to simulate the complicated unsteady flow in Pelton bucket, it is necessary to apply the animated cartoon approach. In this paper, a free jet and the inner surface of a bucket is described by boundary fitted grid (BFG) with non-orthogonal curvilinear coordinates. The water flow is discretized in space and time for CFD (computational fluid dynamics). The moving grids of water film are successfully projected onto the bucket’s inner surface by a projection algorithm. The visualization result of the jet landing on bucket’s surface and the unsteady flow in the rotating buckets in 3D verifies the effectiveness of the proposed method.
基金supported by the National Basic Research Program of China (973 program) "Activity characteristics and formation rules of secondary mountain hazard of earthquake" (Grant No.2008CB425802)Key Program of Chinese Academy of Sciences (No.KZCX2-YW-302-02)
文摘When water seeps upwards through a saturated soil layer,the soil layer may become instability and water films occur and develop.Water film serves as a natural sliding surface because of its very small friction.Accordingly,debris flow may happen.To investigate this phenomenon,a pseudothree-phase media is presented first.Then discontinuity method is used to analyze the expansion velocity of water film.Finally,perturbation method is used to analyze the case that a water flow is forced to seep upwards through the soil layer while the movement of the skeleton may be neglected relative to that of water.The theoretical evolutions of pore pressure gradient,effective stress,water velocity,the porosity and the eroded fine grains are obtained.It can be seen clearly that with the erosion and redeposited of fine grains,permeability at some positions in the soil layer becomes smaller and smaller and,the pore pressure gradient becomes bigger and bigger,while the effective stress becomes smaller and smaller.When the effective stress equals zero,e.f.liquefaction,the water film occurs.It is shown also that once a water film occurs,it will be expanded in a speed of U(t)(1-ε).
基金Supported by the National Natural Science Foundation of China(Grant No.59995460)
文摘The liquid phase turbulent structure of an air-water bubbly horizontal flow in a circular pipe has been investigated experimentally. Three-dimensional measurements were implemented with two "X" type probes oriented in different planes, and local liquid-phase velocities and turbulent stresses were simultaneously obtained. Systematic measurements were conducted covering a range of local void fraction from 0 to 11.7%. The important experiment results and parametric trends are summarized and discussed.
基金TheNationalNaturalScienceFoundationofChina (No .5 96 780 18)
文摘Water quality within water distribution system may vary with both location and time. Water quality models are used to predict the spatial and temporal variation of water quality throughout water system. A model of residual chlorine decay in water pipe has been developed, given the consumption of chlorine in reactions with chemicals in bulk water, bio films on pipe wall, in corrosion process, and the mass transport of chlorine from bulk water to pipe wall. Analytical methods of the flow path from water sources to the observed point and the water age of every observed node were proposed. Model is used to predict the decay of residual chlorine in an actual distribution system. Good agreement between calculated and measured values was obtained.
文摘Subject code:E02 With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhou Jun(周军)from Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Prof.Guo Wanlin(郭万林)from Nanjing University
基金supported by Rotor Aerodynamics Key Laboratory[Grant Number RAL20180401].
文摘A numerical method for the analysis of the electrothermal deicing system for an airfoil is developed taking into account mass and heat exchange at the moving boundary that separates the water film created due to droplet impingement and the ice accretion region.The method relies on a Eulerian approach(used to capture droplet dynamics)and an unsteady heat transfer model(specifically conceived for a multilayer electrothermal problem on the basis of the enthalpy theory and a phase-change correction approach).Through application of the continuous boundary condition for temperature and heat flux at the coupled movingboundary,several simulations of ice accretion,melting and shedding,runback water flow and refreezing phenomena during the electrothermal deicing process are conducted.Finally,the results are verified via comparison with experimental data.A rich set of data concerning the dynamic evolution of the distribution of surface temperature,water film height and ice shape is presented and critically discussed.
