Following the startup oran ecological protection project of “substituting SHP (small hydropower) for fuel”, a new round of SHP construc tion is going to reach its climax. China has numerous rivers, and statistics sh...Following the startup oran ecological protection project of “substituting SHP (small hydropower) for fuel”, a new round of SHP construc tion is going to reach its climax. China has numerous rivers, and statistics shows there are more than 50,000 each with a drainage area of over 100km^2, among them only 1,580 rivers展开更多
A new regional dust model suitable for simula-tion and forecasting of dust storms over northern China was described. The dust model was developed by coupling the mesoscale dynamics model MM5 (the Fifth-Generation NCAR...A new regional dust model suitable for simula-tion and forecasting of dust storms over northern China was described. The dust model was developed by coupling the mesoscale dynamics model MM5 (the Fifth-Generation NCAR/Penn State Mesoscale Model) with a set of mass conservation equations for the particles. The model includes all the atmospheric physical processes of dust storms including occurrence, lifting, transport, and dry and wet deposition. It considers the parameterization of dry and wet deposition, the dust size distribution and microphysical processes in detail. The dust flux from the surface is parameterized based on the friction velocity, which is provided by the mesoscale nonhydrostatic dynamics model, which takes account of the vegetation coverage, land use, soil category, and soil moisture. This new dust model is used to simulate the dust storm that occurred on 1921 March, 2002 in North China. The results show that there is high dust concentration and its movement is consistent with the surface weather record and satellite monitoring images of the observed dust storm. The simulated dust concentration coincides with the observation data of the particulate concentration of PM10 (dust particles smaller than 10 m in diameter). The new numerical model also successfully simulates the formation and migration of the dust storm of 68 April, 2002 in North China.展开更多
This paper presents a numerical simulation method developed for separated flow in cascades using the Euler equations and demonstrates the feasibility of this method.MacCormack's two-steps explicit finite differenc...This paper presents a numerical simulation method developed for separated flow in cascades using the Euler equations and demonstrates the feasibility of this method.MacCormack's two-steps explicit finite difference scheme is used to discretize the equations in conservation form,and the artificial viscosity is added to the dis- cretized inviscid equations by means of the self-adapted filter technique.The initial separation boundary is given according to simple experimental results.The numerical simulation results including subsonic and transonic turbine cascades flow with or without separation show that the fundamental idea of this numerical method is reasonable and simple.The present study indicates that for solving certain engineering problems it is a simple and effective tool for adding some viscosity corrections to inviscid flow model,especially the current when the Navier-Stokes equations have not been solved very effectively for various complicated flows in turbomachinery.展开更多
文摘Following the startup oran ecological protection project of “substituting SHP (small hydropower) for fuel”, a new round of SHP construc tion is going to reach its climax. China has numerous rivers, and statistics shows there are more than 50,000 each with a drainage area of over 100km^2, among them only 1,580 rivers
文摘A new regional dust model suitable for simula-tion and forecasting of dust storms over northern China was described. The dust model was developed by coupling the mesoscale dynamics model MM5 (the Fifth-Generation NCAR/Penn State Mesoscale Model) with a set of mass conservation equations for the particles. The model includes all the atmospheric physical processes of dust storms including occurrence, lifting, transport, and dry and wet deposition. It considers the parameterization of dry and wet deposition, the dust size distribution and microphysical processes in detail. The dust flux from the surface is parameterized based on the friction velocity, which is provided by the mesoscale nonhydrostatic dynamics model, which takes account of the vegetation coverage, land use, soil category, and soil moisture. This new dust model is used to simulate the dust storm that occurred on 1921 March, 2002 in North China. The results show that there is high dust concentration and its movement is consistent with the surface weather record and satellite monitoring images of the observed dust storm. The simulated dust concentration coincides with the observation data of the particulate concentration of PM10 (dust particles smaller than 10 m in diameter). The new numerical model also successfully simulates the formation and migration of the dust storm of 68 April, 2002 in North China.
文摘This paper presents a numerical simulation method developed for separated flow in cascades using the Euler equations and demonstrates the feasibility of this method.MacCormack's two-steps explicit finite difference scheme is used to discretize the equations in conservation form,and the artificial viscosity is added to the dis- cretized inviscid equations by means of the self-adapted filter technique.The initial separation boundary is given according to simple experimental results.The numerical simulation results including subsonic and transonic turbine cascades flow with or without separation show that the fundamental idea of this numerical method is reasonable and simple.The present study indicates that for solving certain engineering problems it is a simple and effective tool for adding some viscosity corrections to inviscid flow model,especially the current when the Navier-Stokes equations have not been solved very effectively for various complicated flows in turbomachinery.
