The velocity slip of gas flow in a micron channel has been widely recognized.For pressure driven liquid flow in a macro pipe,theminute velocity slip at the wall boundary is usually neglected.With a decreasing scale in...The velocity slip of gas flow in a micron channel has been widely recognized.For pressure driven liquid flow in a macro pipe,theminute velocity slip at the wall boundary is usually neglected.With a decreasing scale in the cross section of the flow passage,the effect of velocity slip on flow and heat transfer behaviors becomes progressively more noticeable.Based on the three Hamaker homogeneous material hypotheses,the method for calculating the acting force between the solid and liquid molecular groups is established.By analyzing the forces exerted on the liquid group near the pipe wall,it is found that the active force arising from the rough solid wall can provide the component force to resist the shearing force and keep the liquid group immobile.Based on this a velocity slip criterion is proposed.Considering the force balance of a slipping liquid group,the frictional force caused by the solid wall can be obtained and then the velocity of the liquid group can be calculated using the derived coefficient of friction.The investigation reveals that,in a micron pipe,a small velocity slip may occur when the flow pressure gradient is relatively large,and will cause errors in the pipe flow estimates.展开更多
The ceramic membrane oxygen generation technology has advantages of high concentration of produced oxygen and potential nuclear and biochemical protection capability. The present paper studies the ceramic membrane tec...The ceramic membrane oxygen generation technology has advantages of high concentration of produced oxygen and potential nuclear and biochemical protection capability. The present paper studies the ceramic membrane technology for onboard oxygen generation. Comparisons are made to have knowledge of the effects of two kinds of ceramic membrane separation technologies on oxygen generation, namely electricity driven ceramic membrane separation oxygen generation technology (EDCMSOGT) and pressure driven ceramic membrane separation oxygen generation technology (PDCMSOGT). Experiments were conducted under different temperatures, pressures of feed air and produced oxygen flow rates. On the basis of these experiments, the flow rate of feed air, electric power provided, oxygen recovery rate and concentration of produced oxygen are compared under each working condition. It is concluded that the EDCMSOGT is the oxygen generation means more suitable for onboard conditions. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd.展开更多
基金supported by the National Natural Science Foundation of China (10872088)the Doctoral Foundation of Ministry of Education of China (20070291004 and 20093221120009)the Academic Discipline Construction Fund of Nanjing University of Technology
文摘The velocity slip of gas flow in a micron channel has been widely recognized.For pressure driven liquid flow in a macro pipe,theminute velocity slip at the wall boundary is usually neglected.With a decreasing scale in the cross section of the flow passage,the effect of velocity slip on flow and heat transfer behaviors becomes progressively more noticeable.Based on the three Hamaker homogeneous material hypotheses,the method for calculating the acting force between the solid and liquid molecular groups is established.By analyzing the forces exerted on the liquid group near the pipe wall,it is found that the active force arising from the rough solid wall can provide the component force to resist the shearing force and keep the liquid group immobile.Based on this a velocity slip criterion is proposed.Considering the force balance of a slipping liquid group,the frictional force caused by the solid wall can be obtained and then the velocity of the liquid group can be calculated using the derived coefficient of friction.The investigation reveals that,in a micron pipe,a small velocity slip may occur when the flow pressure gradient is relatively large,and will cause errors in the pipe flow estimates.
文摘The ceramic membrane oxygen generation technology has advantages of high concentration of produced oxygen and potential nuclear and biochemical protection capability. The present paper studies the ceramic membrane technology for onboard oxygen generation. Comparisons are made to have knowledge of the effects of two kinds of ceramic membrane separation technologies on oxygen generation, namely electricity driven ceramic membrane separation oxygen generation technology (EDCMSOGT) and pressure driven ceramic membrane separation oxygen generation technology (PDCMSOGT). Experiments were conducted under different temperatures, pressures of feed air and produced oxygen flow rates. On the basis of these experiments, the flow rate of feed air, electric power provided, oxygen recovery rate and concentration of produced oxygen are compared under each working condition. It is concluded that the EDCMSOGT is the oxygen generation means more suitable for onboard conditions. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd.
