The dynamical behavior of two tethered rigid spheres in a supersonic flow is numerically investigated. The tethered lengths and radius ratios of the two spheres are different. The two spheres, which are centroid axial...The dynamical behavior of two tethered rigid spheres in a supersonic flow is numerically investigated. The tethered lengths and radius ratios of the two spheres are different. The two spheres, which are centroid axially aligned initially, are held stationary first, then released, and subsequently let fly freely in a supersonic flow. The mean qualities of the system and the qualities of the bigger sphere are considered and compared with the situations without the tether. In the separation process, six types of motion caused by the spheres, tether, and fluid interaction are found. The results show that the mean x-velocity of the system changes in a different manner for different radius ratios, and the x-velocity of the bigger sphere is uniformly reduced but through different mechanisms.展开更多
The numerical simulation model is proposed according to the characteristics of the biomass briquette fuels, which involves two main areas of interest: the solid combustion model in the bed and the out-of-bed gas combu...The numerical simulation model is proposed according to the characteristics of the biomass briquette fuels, which involves two main areas of interest: the solid combustion model in the bed and the out-of-bed gas combustion model. The contents and characteristics of 3 kinds of biomass and coals were experimentally tested. The biomass fuels compared with the coal fuel have the following characteristics: 1) Higher volatile content, lower fixed carbon content and calorific value;2) Lower carbon content, higher oxygen content;3) Lower ignition temperature, faster burning velocity. The discredited equations were established by the finite element analysis method, which analyzed the fuel endothermic process on the grate, while the out-of-bed gas combustion process was simulated by CFD. These two processes are strongly coupled. The results of the numerical simulation contain the steady state temperature distribution, oxygen distribution, carbon dioxide distribution and so on, which are used to judge burning effect and provide the correct furnace transformation method.展开更多
基金supported by the National Natural Science Foundation of China(No.11372068)the National Key Basic Research and Development Program of China(973 Program)(No.2014CB-744104)
文摘The dynamical behavior of two tethered rigid spheres in a supersonic flow is numerically investigated. The tethered lengths and radius ratios of the two spheres are different. The two spheres, which are centroid axially aligned initially, are held stationary first, then released, and subsequently let fly freely in a supersonic flow. The mean qualities of the system and the qualities of the bigger sphere are considered and compared with the situations without the tether. In the separation process, six types of motion caused by the spheres, tether, and fluid interaction are found. The results show that the mean x-velocity of the system changes in a different manner for different radius ratios, and the x-velocity of the bigger sphere is uniformly reduced but through different mechanisms.
文摘The numerical simulation model is proposed according to the characteristics of the biomass briquette fuels, which involves two main areas of interest: the solid combustion model in the bed and the out-of-bed gas combustion model. The contents and characteristics of 3 kinds of biomass and coals were experimentally tested. The biomass fuels compared with the coal fuel have the following characteristics: 1) Higher volatile content, lower fixed carbon content and calorific value;2) Lower carbon content, higher oxygen content;3) Lower ignition temperature, faster burning velocity. The discredited equations were established by the finite element analysis method, which analyzed the fuel endothermic process on the grate, while the out-of-bed gas combustion process was simulated by CFD. These two processes are strongly coupled. The results of the numerical simulation contain the steady state temperature distribution, oxygen distribution, carbon dioxide distribution and so on, which are used to judge burning effect and provide the correct furnace transformation method.
