The high potential of geothermal energy in quantity and availability can be a great option, facing the huge problem of growing energy use linked with the climatic problems. Therefore, it is necessary to reduce costs a...The high potential of geothermal energy in quantity and availability can be a great option, facing the huge problem of growing energy use linked with the climatic problems. Therefore, it is necessary to reduce costs and risks for the use of geothermal energy sources. Because most of the problems have to do with insufficient knowledge about the conditions in the earth crust, the key to take root of geothermal energy is widespread research. The cooling system allows the use of all needed devices in deep boreholes without strict time or temperature limitations, which promotes the achieving of comprehensive information. To develop the purpose-built components among conducting experiments about the thermodynamic processes, a prototype is provided step by step.展开更多
Numerical experiments are carried out using the standard hypersonic ballistic-type model(HB-2) to investigate the effect of forward-facing cavity on the aerodynamic heating. A general concept is proposed which utilize...Numerical experiments are carried out using the standard hypersonic ballistic-type model(HB-2) to investigate the effect of forward-facing cavity on the aerodynamic heating. A general concept is proposed which utilizes the flow disturbances generated passively in the nosed subsonic region to weaken the detached shock wave. Several aspects are mainly studied, including shock shape and standoff distance, surface heat flux and pressure, flowfield feature and cooling mechanism. The numerical results indicate that shock strength and standoff distance increase with an increase in the L/D ratio of the cavity. Interestingly, a bulge structure of the detached shock associated with a deep cavity is observed for the first time. Local surface heat flux and pressure around the concave nose are much lower respectively than those at the stagnation point of the baseline model. In addition, both surface heat and pressure reductions are proportional to the L/D ratio. A negative heating phenomenon may occur in the vicinity of a sharp lip or on the base wall of a deep cavity. If the L/D ratio exceeds 0.7, the detached shock appears as a self-sustained oscillation which can be referred to as the cooling mechanism.展开更多
文摘The high potential of geothermal energy in quantity and availability can be a great option, facing the huge problem of growing energy use linked with the climatic problems. Therefore, it is necessary to reduce costs and risks for the use of geothermal energy sources. Because most of the problems have to do with insufficient knowledge about the conditions in the earth crust, the key to take root of geothermal energy is widespread research. The cooling system allows the use of all needed devices in deep boreholes without strict time or temperature limitations, which promotes the achieving of comprehensive information. To develop the purpose-built components among conducting experiments about the thermodynamic processes, a prototype is provided step by step.
基金supported by the National Natural Science Foundation of China(Grant No.11532014)
文摘Numerical experiments are carried out using the standard hypersonic ballistic-type model(HB-2) to investigate the effect of forward-facing cavity on the aerodynamic heating. A general concept is proposed which utilizes the flow disturbances generated passively in the nosed subsonic region to weaken the detached shock wave. Several aspects are mainly studied, including shock shape and standoff distance, surface heat flux and pressure, flowfield feature and cooling mechanism. The numerical results indicate that shock strength and standoff distance increase with an increase in the L/D ratio of the cavity. Interestingly, a bulge structure of the detached shock associated with a deep cavity is observed for the first time. Local surface heat flux and pressure around the concave nose are much lower respectively than those at the stagnation point of the baseline model. In addition, both surface heat and pressure reductions are proportional to the L/D ratio. A negative heating phenomenon may occur in the vicinity of a sharp lip or on the base wall of a deep cavity. If the L/D ratio exceeds 0.7, the detached shock appears as a self-sustained oscillation which can be referred to as the cooling mechanism.
