The effects of tube bank configuration on forces and heat transfer were investigated for both two-dimensional and three-dimensional gas fluidized beds. Effective dynamic forces and heat transfer coefficients were meas...The effects of tube bank configuration on forces and heat transfer were investigated for both two-dimensional and three-dimensional gas fluidized beds. Effective dynamic forces and heat transfer coefficients were measured for several tube bank configurations, and it was found that the average forces are smaller than for a single tube. The heat transfer coefficient can be increased by providing sufficient space for particles to descend around both sides of the tube bank. The results provide useful guidelines for optimizing the configuration of tube banks to achieve high heat transfer coefficients while reducing tube erosion due to dynamic forces.展开更多
An evolving material structure is in a non-equilibrium state, with free energy expressed by the generalized coordinates. A global approach leads to robust computations for the generalized thermodynamic forces. Those f...An evolving material structure is in a non-equilibrium state, with free energy expressed by the generalized coordinates. A global approach leads to robust computations for the generalized thermodynamic forces. Those forces drive various kinetic processes, causing dissipation at spots, along curves, surfaces and interfaces, and within volumetric regions. The actual evolution path, and therefore the final equilibrium state, is determined by the energetics and kinetics. A virtual work principle Links the free energy landscape and the kinetic processes, and assigns a viscous environment to every point on the landscape. The approach leads to a dynamical system that governs the evolution of generalized coordinates. The microstructural evolution is globally characterized by a basin map in the coordinate space; and by a diversity map and a variety map in the parameter space. The control of basin boundaries raises the issue of energetic and kinetic bifurcations. The variation of basin boundaries under different sets of controlling parameters provides an analytical way to plot the diversity maps of structural evolution.展开更多
A topology method is presented in this paper to reveal flow structure occurring inside turbomachinery,in which near wall now structure is revealed by using wall limiting streamlines and space flow feature is revealed ...A topology method is presented in this paper to reveal flow structure occurring inside turbomachinery,in which near wall now structure is revealed by using wall limiting streamlines and space flow feature is revealed by using space streamlines and cross-section streamlines. As an example, a computational three-dimensional viscous flow field inside a transonic turbine cascade is studied. Through the analysis,the form and evolution of vortex system and the whole process of separation occurring within this cascade are revealed. The application of topology method for analyze fiow structure inside turbomachinery is very important for understanding flow features and mechanism of flow loss even for improving the design of turbomachinery and increasing its efficiency.展开更多
A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the ...A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.展开更多
This paper will present the characteristics of flow behavior and thermal field of both free and impingement jet issued from a circular orifice nozzle at Re=8900.The flow behavior of a single round jet and impingement ...This paper will present the characteristics of flow behavior and thermal field of both free and impingement jet issued from a circular orifice nozzle at Re=8900.The flow behavior of a single round jet and impingement jet was observed by smoke flow visualization recorded by a high speed camera using 5000 frame per second.Heat transfer coefficient on the impingement surface was measured by means of infrared camera (TVS-8500,Avio) with a two-dimensional array of Indeum-Antimony (In Sb) sensors varying in the separation distance between the nozzle and the target plate.The heat transfer coefficient changes in time and spatial.Therefore,the root mean square distribution of the heat transfer was obtained from the data.As a result,it was confirmed that the longitudinal vortex was observed outside of the ring vortex,and then the longitudinal vortex was penetrated in the jet flow.Moreover,the high value of root mean square of the heat transfer coefficient has spread radially in stripy manner,which is caused as the results of the longitudinal vortexes flowing in the radial direction on the impingement plate.展开更多
基金the Natural Sciences and Engineering Research Council of Canada
文摘The effects of tube bank configuration on forces and heat transfer were investigated for both two-dimensional and three-dimensional gas fluidized beds. Effective dynamic forces and heat transfer coefficients were measured for several tube bank configurations, and it was found that the average forces are smaller than for a single tube. The heat transfer coefficient can be increased by providing sufficient space for particles to descend around both sides of the tube bank. The results provide useful guidelines for optimizing the configuration of tube banks to achieve high heat transfer coefficients while reducing tube erosion due to dynamic forces.
基金The project supported by the National Science Foundation(USA)through grant MSS-9258115by the National Natural Science Foundation of China
文摘An evolving material structure is in a non-equilibrium state, with free energy expressed by the generalized coordinates. A global approach leads to robust computations for the generalized thermodynamic forces. Those forces drive various kinetic processes, causing dissipation at spots, along curves, surfaces and interfaces, and within volumetric regions. The actual evolution path, and therefore the final equilibrium state, is determined by the energetics and kinetics. A virtual work principle Links the free energy landscape and the kinetic processes, and assigns a viscous environment to every point on the landscape. The approach leads to a dynamical system that governs the evolution of generalized coordinates. The microstructural evolution is globally characterized by a basin map in the coordinate space; and by a diversity map and a variety map in the parameter space. The control of basin boundaries raises the issue of energetic and kinetic bifurcations. The variation of basin boundaries under different sets of controlling parameters provides an analytical way to plot the diversity maps of structural evolution.
文摘A topology method is presented in this paper to reveal flow structure occurring inside turbomachinery,in which near wall now structure is revealed by using wall limiting streamlines and space flow feature is revealed by using space streamlines and cross-section streamlines. As an example, a computational three-dimensional viscous flow field inside a transonic turbine cascade is studied. Through the analysis,the form and evolution of vortex system and the whole process of separation occurring within this cascade are revealed. The application of topology method for analyze fiow structure inside turbomachinery is very important for understanding flow features and mechanism of flow loss even for improving the design of turbomachinery and increasing its efficiency.
文摘A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.
文摘This paper will present the characteristics of flow behavior and thermal field of both free and impingement jet issued from a circular orifice nozzle at Re=8900.The flow behavior of a single round jet and impingement jet was observed by smoke flow visualization recorded by a high speed camera using 5000 frame per second.Heat transfer coefficient on the impingement surface was measured by means of infrared camera (TVS-8500,Avio) with a two-dimensional array of Indeum-Antimony (In Sb) sensors varying in the separation distance between the nozzle and the target plate.The heat transfer coefficient changes in time and spatial.Therefore,the root mean square distribution of the heat transfer was obtained from the data.As a result,it was confirmed that the longitudinal vortex was observed outside of the ring vortex,and then the longitudinal vortex was penetrated in the jet flow.Moreover,the high value of root mean square of the heat transfer coefficient has spread radially in stripy manner,which is caused as the results of the longitudinal vortexes flowing in the radial direction on the impingement plate.
