The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic f...The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent.展开更多
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
基金Project(2007CB707706) supported by the Major State Basic Research Development Program of ChinaProjects(2007E213,2007E203) supported by the Natural Science Foundation of Shaanxi Province,China
文摘The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent.
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.
