For the 110 mining method,it is challenging to accurately calculate the support resistance of the roadway due to the lack of understanding of the dynamic movement of the overlying strata in this method.The consequenti...For the 110 mining method,it is challenging to accurately calculate the support resistance of the roadway due to the lack of understanding of the dynamic movement of the overlying strata in this method.The consequential excessive support results in a significant increase in the cost of roadway support.The authors explored the overlying strata movement and roadway deformation of the gob-entry retaining in the 110 mining method to solve this problem.First,the typical stages of the roof-cutting gob-side entry were defined.Second,the mechanical model and calculation formula of the support resistance on the roof were explored.Then,using numerical simulation software,the starting ranges of the specific supports at different stages were verified and the feasibility of the support scheme was examined.Finally,combined with the field measurement data,the stress and the deformation of the gob roadway at different stages under the influence of two mining processes in the 110 mining method were obtained.The numerical simulation results obtained are consistent with the field test results,providing a theoretical basis for precision support at different stages by the 110 mining method.展开更多
By using the finite volume method with volume of fluid model and global dynamic mesh technique, the effects of Froude number and geometry on the water entry process of a 2-D ellipse are investigated numerically. For t...By using the finite volume method with volume of fluid model and global dynamic mesh technique, the effects of Froude number and geometry on the water entry process of a 2-D ellipse are investigated numerically. For the time history of the vertical force, the computational fluid dynamics（CFD） results match the experimental data much better than the classical potential-flow theories due to the consideration of the viscosity, turbulence, surface tension, gravity, and compressibility. The results show that the position of peak pressure on ellipse shifts from the spray root to the bottom of ellipse at a critical time. The critical time changes with the geometry and Froude number. By studying the vertical force, the ellipse water entry process can be divided into the initial and late stages based on the critical dimensionless time of about 0.1. The geometry of the ellipse plays a dominant role in the initial stage, while the Froude number is more important in the late stage of entry. The classical Wagner theory is extended to the ellipse water entry, and the predicted maximum value of vertical force coefficient in the initial stage is 4？a/b that matches the CFD results very well, where a and b are the horizontal axis and vertical axis of the ellipse parallel and perpendicular to the initial calm water surface, respectively.展开更多
The interaction between free surface flow and structure is investigated using a new level set immersed boundary method.The incorporation of an improved immersed boundary method with a free surface capture scheme imple...The interaction between free surface flow and structure is investigated using a new level set immersed boundary method.The incorporation of an improved immersed boundary method with a free surface capture scheme implemented in a Navier-Stokes solver allows the interaction between fluid flow with free surface and moving body/bodies of almost arbitrary shape to be modelled.A new algorithm is proposed to locate exact forcing points near solid boundaries,which provides an accurate numerical solution.The discretized linear system of the Poisson pressure equation is solved using the Generalized Minimum Residual(GMRES)method with incomplete LU preconditioning.Uniform flow past a cylinder at Reynolds number Re=100 is modelled using the present model and results agree well with the experiment and numerical data in the literature.Water exit and entry of a cylinder at the prescribed velocity is also investigated.The predicted slamming coefficient is in good agreement with experimental data and previous numerical simulations using a ComFlow model.The vertical slamming force and pressure distribution for the free falling wedge is also studied by the present model and comparisons with available theoretical solutions and experimental data are made.展开更多
基金Project(51674265) supported by the National Natural Science Foundation of ChinaProjects(2018YFC0603705,2016YFC0600901) supported by the State Key Research Development Program of ChinaProject supported by the Yueqi Outstanding Scholar Award Program of China University of Mining&Technology,Beijing,China。
文摘For the 110 mining method,it is challenging to accurately calculate the support resistance of the roadway due to the lack of understanding of the dynamic movement of the overlying strata in this method.The consequential excessive support results in a significant increase in the cost of roadway support.The authors explored the overlying strata movement and roadway deformation of the gob-entry retaining in the 110 mining method to solve this problem.First,the typical stages of the roof-cutting gob-side entry were defined.Second,the mechanical model and calculation formula of the support resistance on the roof were explored.Then,using numerical simulation software,the starting ranges of the specific supports at different stages were verified and the feasibility of the support scheme was examined.Finally,combined with the field measurement data,the stress and the deformation of the gob roadway at different stages under the influence of two mining processes in the 110 mining method were obtained.The numerical simulation results obtained are consistent with the field test results,providing a theoretical basis for precision support at different stages by the 110 mining method.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11302015,11272034)
文摘By using the finite volume method with volume of fluid model and global dynamic mesh technique, the effects of Froude number and geometry on the water entry process of a 2-D ellipse are investigated numerically. For the time history of the vertical force, the computational fluid dynamics（CFD） results match the experimental data much better than the classical potential-flow theories due to the consideration of the viscosity, turbulence, surface tension, gravity, and compressibility. The results show that the position of peak pressure on ellipse shifts from the spray root to the bottom of ellipse at a critical time. The critical time changes with the geometry and Froude number. By studying the vertical force, the ellipse water entry process can be divided into the initial and late stages based on the critical dimensionless time of about 0.1. The geometry of the ellipse plays a dominant role in the initial stage, while the Froude number is more important in the late stage of entry. The classical Wagner theory is extended to the ellipse water entry, and the predicted maximum value of vertical force coefficient in the initial stage is 4？a/b that matches the CFD results very well, where a and b are the horizontal axis and vertical axis of the ellipse parallel and perpendicular to the initial calm water surface, respectively.
基金the support of the South West of England Regional Development Agency in funding this project through Peninsular Research Institute for Marine Renewable Energy(http://www.primare.org/).
文摘The interaction between free surface flow and structure is investigated using a new level set immersed boundary method.The incorporation of an improved immersed boundary method with a free surface capture scheme implemented in a Navier-Stokes solver allows the interaction between fluid flow with free surface and moving body/bodies of almost arbitrary shape to be modelled.A new algorithm is proposed to locate exact forcing points near solid boundaries,which provides an accurate numerical solution.The discretized linear system of the Poisson pressure equation is solved using the Generalized Minimum Residual(GMRES)method with incomplete LU preconditioning.Uniform flow past a cylinder at Reynolds number Re=100 is modelled using the present model and results agree well with the experiment and numerical data in the literature.Water exit and entry of a cylinder at the prescribed velocity is also investigated.The predicted slamming coefficient is in good agreement with experimental data and previous numerical simulations using a ComFlow model.The vertical slamming force and pressure distribution for the free falling wedge is also studied by the present model and comparisons with available theoretical solutions and experimental data are made.
