Hyper-gravity experiment enable the acceleration of the long-term transport of contaminants through fractured geological barriers.However,the hyper-gravity effect of the solute transport in fractures are not well unde...Hyper-gravity experiment enable the acceleration of the long-term transport of contaminants through fractured geological barriers.However,the hyper-gravity effect of the solute transport in fractures are not well understood.In this study,the sealed control apparatus and the 3D printed fracture models were used to carry out 1 g and N g hyper-gravity experiments.The results show that the breakthrough curves for the 1 g and N g experiments were almost the same.The differences in the flow velocity and the fitted hydrodynamic dispersion coefficient were 0.97–3.12%and 9.09–20.4%,indicating that the internal fractures of the 3D printed fracture models remained stable under hyper-gravity,and the differences in the flow and solute transport characteristics were acceptable.A method for evaluating the long-term barrier performance of low-permeability fractured rocks was proposed based on the hyper-gravity experiment.The solute transport processes in the 1 g prototype,1 g scaled model,and N g scaled model were simulated by the OpenGeoSys(OGS)software.The results show that the N g scaled model can reproduce the flow and solute transport processes in the 1 g prototype without considering the micro-scale heterogeneity if the Reynolds number(Re)critical Reynolds number(Recr)and the Peclet number(Pe)the critical Peclet number(Pecr).This insight is valuable for carrying out hyper-gravity experiments to evaluate the long-term barrier performance of low-permeability fractured porous rock.展开更多
Droplet-based high heat flux dissipation technique under multi-gravitational environments has gained increasing research attention due to the increased requirements of heat dissipation in advanced air-/space-borne ele...Droplet-based high heat flux dissipation technique under multi-gravitational environments has gained increasing research attention due to the increased requirements of heat dissipation in advanced air-/space-borne electronics.In this paper,a threedimensional model was developed to investigate the impact of continuous droplets on liquid film under various Weber numbers and gravity loads.In other words,the effects of Weber number and gravity load on the flow and heat transfer characteristics were investigated.The results demonstrated that the dissipated heat flux was positively correlated with both Weber number and gravity load.A large Weber number indicated larger kinetic energy of a droplet,leading to a greater disturbance on the impacted film area.When the Weber number was doubled,the average wall heat flux could be enhanced by 36.3%.In addition,the heat flux could be boosted by 5.4%when the gravity load ranged from 0 to 1g.Moreover,a weightless condition suppressed the vapor escape rates on the heating wall where the volume fraction of the vapor on the wall could increase by 20%under 0g,leading to deteriorated heat transfer performance.The novelty in this paper lies in the accurate three-dimensional modeling of an aerospaceoriented droplet impacting two-phase heat transfer and fluid dynamics,associating macro-scale thermal performance to microscale thermophysics mechanisms.The findings of this study could guide the development of aerospace-borne spray cooling facilities for advanced aerospace thermal management.展开更多
基金supported by the Basic Science Center Program for Multiphase Evolution in Hypergravity of the National Natural Science Foundation of China(No.51988101)the National Key Research and Development Project China(No.2018YFC1802300)+1 种基金the National Natural Science Foundation of China(No.42007262)the National Natural Science Foundation of China(No.42277128).
文摘Hyper-gravity experiment enable the acceleration of the long-term transport of contaminants through fractured geological barriers.However,the hyper-gravity effect of the solute transport in fractures are not well understood.In this study,the sealed control apparatus and the 3D printed fracture models were used to carry out 1 g and N g hyper-gravity experiments.The results show that the breakthrough curves for the 1 g and N g experiments were almost the same.The differences in the flow velocity and the fitted hydrodynamic dispersion coefficient were 0.97–3.12%and 9.09–20.4%,indicating that the internal fractures of the 3D printed fracture models remained stable under hyper-gravity,and the differences in the flow and solute transport characteristics were acceptable.A method for evaluating the long-term barrier performance of low-permeability fractured rocks was proposed based on the hyper-gravity experiment.The solute transport processes in the 1 g prototype,1 g scaled model,and N g scaled model were simulated by the OpenGeoSys(OGS)software.The results show that the N g scaled model can reproduce the flow and solute transport processes in the 1 g prototype without considering the micro-scale heterogeneity if the Reynolds number(Re)critical Reynolds number(Recr)and the Peclet number(Pe)the critical Peclet number(Pecr).This insight is valuable for carrying out hyper-gravity experiments to evaluate the long-term barrier performance of low-permeability fractured porous rock.
基金supported by the National Natural Science Foundation of China (Grant Nos.52106114,51725602,and 52036006)。
文摘Droplet-based high heat flux dissipation technique under multi-gravitational environments has gained increasing research attention due to the increased requirements of heat dissipation in advanced air-/space-borne electronics.In this paper,a threedimensional model was developed to investigate the impact of continuous droplets on liquid film under various Weber numbers and gravity loads.In other words,the effects of Weber number and gravity load on the flow and heat transfer characteristics were investigated.The results demonstrated that the dissipated heat flux was positively correlated with both Weber number and gravity load.A large Weber number indicated larger kinetic energy of a droplet,leading to a greater disturbance on the impacted film area.When the Weber number was doubled,the average wall heat flux could be enhanced by 36.3%.In addition,the heat flux could be boosted by 5.4%when the gravity load ranged from 0 to 1g.Moreover,a weightless condition suppressed the vapor escape rates on the heating wall where the volume fraction of the vapor on the wall could increase by 20%under 0g,leading to deteriorated heat transfer performance.The novelty in this paper lies in the accurate three-dimensional modeling of an aerospaceoriented droplet impacting two-phase heat transfer and fluid dynamics,associating macro-scale thermal performance to microscale thermophysics mechanisms.The findings of this study could guide the development of aerospace-borne spray cooling facilities for advanced aerospace thermal management.
