The constitutive model of rock can be built by mechanics elements because there are many kinds of damages in rock under varied loads.It is resumed that rock contains many microstructures and a structure of Bingham.The...The constitutive model of rock can be built by mechanics elements because there are many kinds of damages in rock under varied loads.It is resumed that rock contains many microstructures and a structure of Bingham.The microstructure consists of two embranchments that are the unit of a spring and a gliding slice in series and the unit of a spring and a cementation bar in series,the two units connect each other in parallel.These microstructures are arranged disorderly or in the order of a certain state.A certain distribution of microstructures represents one type of rock.Two kinds of rock's constitutive relationship were deduced by using the model.One is the model in which many parallel microstructures and a structure of Bingham connect in series.And it is used to homogeneous rock.The other is the model in which many microstructures and a structure of Bingham connect in series.And it is used to the rock with much crack or microcrack in a certain direction.The two kinds of constitutive relationship were verified by the studied cases.The constitutive model of rock built by using mechanics elements is verified to be reasonable.Moreover,different types of rocks may be described with mechanics elements with different distributions.展开更多
Magnetohydrodynamic （MHD） accelerator is proposed as a next generation propulsion system. It can be used to increase the performance of a propulsion system. The objective of this study is to investigate the performa...Magnetohydrodynamic （MHD） accelerator is proposed as a next generation propulsion system. It can be used to increase the performance of a propulsion system. The objective of this study is to investigate the performance of MHD accelerator using non-equilibrium air plasma as working gas. In this study, the fundamental performance of MHD accelerator such as flow performance and electrical performance is evaluated at different levels of applied magnetic field using I-D numerical simulation. The numerical simulation is developed based on a set of differential equations with MHD approximation. To solve this set of differential equations the MacCormack scheme is used. A specified channel designed and developed at NASA Marshall Space Flight Centre is used in the numerical simulation. The composition of the simulated air plasma consists of seven species, namely, N2, N, O2, O, NO, NO＋, and e-. The performance of the non-equilibrium MHD accelerator is also compared with the equilibrium MHD accelerator.展开更多
基金Projects(10472134,50490274) supported by the National Natural Science Foundation of China
文摘The constitutive model of rock can be built by mechanics elements because there are many kinds of damages in rock under varied loads.It is resumed that rock contains many microstructures and a structure of Bingham.The microstructure consists of two embranchments that are the unit of a spring and a gliding slice in series and the unit of a spring and a cementation bar in series,the two units connect each other in parallel.These microstructures are arranged disorderly or in the order of a certain state.A certain distribution of microstructures represents one type of rock.Two kinds of rock's constitutive relationship were deduced by using the model.One is the model in which many parallel microstructures and a structure of Bingham connect in series.And it is used to homogeneous rock.The other is the model in which many microstructures and a structure of Bingham connect in series.And it is used to the rock with much crack or microcrack in a certain direction.The two kinds of constitutive relationship were verified by the studied cases.The constitutive model of rock built by using mechanics elements is verified to be reasonable.Moreover,different types of rocks may be described with mechanics elements with different distributions.
文摘Magnetohydrodynamic （MHD） accelerator is proposed as a next generation propulsion system. It can be used to increase the performance of a propulsion system. The objective of this study is to investigate the performance of MHD accelerator using non-equilibrium air plasma as working gas. In this study, the fundamental performance of MHD accelerator such as flow performance and electrical performance is evaluated at different levels of applied magnetic field using I-D numerical simulation. The numerical simulation is developed based on a set of differential equations with MHD approximation. To solve this set of differential equations the MacCormack scheme is used. A specified channel designed and developed at NASA Marshall Space Flight Centre is used in the numerical simulation. The composition of the simulated air plasma consists of seven species, namely, N2, N, O2, O, NO, NO＋, and e-. The performance of the non-equilibrium MHD accelerator is also compared with the equilibrium MHD accelerator.
