The transition from froth to spray regime on sieve trays was experimentally studied in an air/water simulator with 300mm diameter. It has been found that the regime transition occurs as the clear liquid height is equa...The transition from froth to spray regime on sieve trays was experimentally studied in an air/water simulator with 300mm diameter. It has been found that the regime transition occurs as the clear liquid height is equal to the residual pressure drop on the trays. A convenient and accurate technique was proposed for determination of the regime transition point. Based on analysis of the transition process at a sieve hole, a new formula which can be used to correlate the experimental results was provided.展开更多
Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characte...Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f o and superficial gas velocity U sg under fixed flowrate of oil-water mixture Q mix . The dynamics of oil-in-water type slug flow becomes more complex with the increase of U sg under fixed flowrate of oil-water mixture. The change of f o leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.展开更多
Modern public buildings, such as multiplex cinemas and theaters, along with application of state of the art sound effects bring high acoustic insulation demands. Cinemas are often a part of building complexes such as ...Modern public buildings, such as multiplex cinemas and theaters, along with application of state of the art sound effects bring high acoustic insulation demands. Cinemas are often a part of building complexes such as shopping malls with subjects that produce serious level of noise and vibrations. Apart to regular use of polyurethane in thermal insulation purposes, it is widely used in field of acoustic insulation. Usage of polyurethane foam pads, with specific dynamic characteristics, as a base for structure supports gives a wide range of possibilities in controlling the amount of structural noise and vibrations transferred to the structure. Structure itself and acoustical pads becomes an integral system that behaves together and need to be analyzed as a whole in extensive design. Dynamic characteristics of acoustic pads depend on stress level and in same time they represent elastic supports to the structure and therefore analyzes and design is an iterative process. In other way, introduce of non-conventional material in bearing structure brings some issues, such as transfer of shear forces, that has to be governed by proper structural detailing. There are several possibilities of application in bearing structures, such as above and below steel structure. This paper gives an overall view on polyurethane as material, construction and design principles and example of usage of acoustic pads in steel structure of＂Ster＂ cineplex in Belgrade.展开更多
The injection of a high pressure gas into a stagnant liquid pool is the characteristic phenomenon during the expansion phase of a hypothetical core disruptive accident in liquid metal cooled fast reactors. In order to...The injection of a high pressure gas into a stagnant liquid pool is the characteristic phenomenon during the expansion phase of a hypothetical core disruptive accident in liquid metal cooled fast reactors. In order to investigate lots of mechanisms involved in this phase of the accident＇s evolution, an experimental campaign called S GI was performed in 1994 in Forschungszentrum Karlsruhe, now KIT. This campaign consists of nine experiments which have been dedicated to assess the effects of different pressure injection, the nozzle＇s size and the presence of inner confinement in the formation of the rising bubble. Three of these experiments, which were focused on the pressure effects, have now been simulated with SIMMER III code and with FLUENT 6.3, a commercial CFD code. Both codes, despite their different features, have showed a good agreement with the experimental results. In particular, time trend evolutions of pressures and bubble volumes have been well reproduced by simulation. Furthermore, both codes agree on the shape of the bubble, even though they have evidenced same discrepancies with the experimental shape.展开更多
The false vacuum decay in field theory from a coherently oscillating initial state is studied for φ6 potential. An oscillating bubble solution is obtained. The instantaneous bubble nucleation rate is calculated.
Three-dimensional （3D） copper foams have been formed by electrodeposition at different nitrogen pressures and examined by scanning electron microscopy. The results indicate that an increase in system pressure leads ...Three-dimensional （3D） copper foams have been formed by electrodeposition at different nitrogen pressures and examined by scanning electron microscopy. The results indicate that an increase in system pressure leads to a decrease of the pore size of the copper foam due to the suppressed coalescence of hydrogen bubbles, while the thickness of the copper foam increases with decreasing pressure. Also, the walls around the pores on the copper foam consist of copper dendrites, and the copper dendrites are made up of copper grains with sizes less than 1 l.tm. The average sizes of the copper grains decrease with increasing system pressure. It has been demonstrated that copper foams with controllable 3D structure formed by electrodeposition at different pressures are comparable to those obtained by electrodeposition at normal pressure in the presence of specific additives.展开更多
基金Supported by the National Natural Science Foundation of China(No.29170288)
文摘The transition from froth to spray regime on sieve trays was experimentally studied in an air/water simulator with 300mm diameter. It has been found that the regime transition occurs as the clear liquid height is equal to the residual pressure drop on the trays. A convenient and accurate technique was proposed for determination of the regime transition point. Based on analysis of the transition process at a sieve hole, a new formula which can be used to correlate the experimental results was provided.
基金Supported by the National Natural Science Foundation of China (50974095, 41174109)Gao Zhongke (高忠科) was also supported by the National Natural Science Foundation of China (61104148)+2 种基金the National Science and Technology Major Projects (2011ZX05020-006)Specialized Research Fund for the Doctoral Program of Higher Education of China(20110032120088)the Independent Innovation Foundation of Tianjin University
文摘Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f o and superficial gas velocity U sg under fixed flowrate of oil-water mixture Q mix . The dynamics of oil-in-water type slug flow becomes more complex with the increase of U sg under fixed flowrate of oil-water mixture. The change of f o leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.
文摘Modern public buildings, such as multiplex cinemas and theaters, along with application of state of the art sound effects bring high acoustic insulation demands. Cinemas are often a part of building complexes such as shopping malls with subjects that produce serious level of noise and vibrations. Apart to regular use of polyurethane in thermal insulation purposes, it is widely used in field of acoustic insulation. Usage of polyurethane foam pads, with specific dynamic characteristics, as a base for structure supports gives a wide range of possibilities in controlling the amount of structural noise and vibrations transferred to the structure. Structure itself and acoustical pads becomes an integral system that behaves together and need to be analyzed as a whole in extensive design. Dynamic characteristics of acoustic pads depend on stress level and in same time they represent elastic supports to the structure and therefore analyzes and design is an iterative process. In other way, introduce of non-conventional material in bearing structure brings some issues, such as transfer of shear forces, that has to be governed by proper structural detailing. There are several possibilities of application in bearing structures, such as above and below steel structure. This paper gives an overall view on polyurethane as material, construction and design principles and example of usage of acoustic pads in steel structure of＂Ster＂ cineplex in Belgrade.
文摘The injection of a high pressure gas into a stagnant liquid pool is the characteristic phenomenon during the expansion phase of a hypothetical core disruptive accident in liquid metal cooled fast reactors. In order to investigate lots of mechanisms involved in this phase of the accident＇s evolution, an experimental campaign called S GI was performed in 1994 in Forschungszentrum Karlsruhe, now KIT. This campaign consists of nine experiments which have been dedicated to assess the effects of different pressure injection, the nozzle＇s size and the presence of inner confinement in the formation of the rising bubble. Three of these experiments, which were focused on the pressure effects, have now been simulated with SIMMER III code and with FLUENT 6.3, a commercial CFD code. Both codes, despite their different features, have showed a good agreement with the experimental results. In particular, time trend evolutions of pressures and bubble volumes have been well reproduced by simulation. Furthermore, both codes agree on the shape of the bubble, even though they have evidenced same discrepancies with the experimental shape.
文摘The false vacuum decay in field theory from a coherently oscillating initial state is studied for φ6 potential. An oscillating bubble solution is obtained. The instantaneous bubble nucleation rate is calculated.
基金supported by the National Natural Science Foundation of China (20776004)the Program for New Century Excellent Talents in University (NCET-08-0710)
文摘Three-dimensional （3D） copper foams have been formed by electrodeposition at different nitrogen pressures and examined by scanning electron microscopy. The results indicate that an increase in system pressure leads to a decrease of the pore size of the copper foam due to the suppressed coalescence of hydrogen bubbles, while the thickness of the copper foam increases with decreasing pressure. Also, the walls around the pores on the copper foam consist of copper dendrites, and the copper dendrites are made up of copper grains with sizes less than 1 l.tm. The average sizes of the copper grains decrease with increasing system pressure. It has been demonstrated that copper foams with controllable 3D structure formed by electrodeposition at different pressures are comparable to those obtained by electrodeposition at normal pressure in the presence of specific additives.
