This paper will introduce experimental studies and numerical calculation on turbulent boundary layer of water flow along curved surface in our country in recent years.On the basis of the experimental studies,the effec...This paper will introduce experimental studies and numerical calculation on turbulent boundary layer of water flow along curved surface in our country in recent years.On the basis of the experimental studies,the effects of curvature and roughness on velocity distribution and pressure distribution and the change of turbulent flow boundary layer on overflow bucket concave surface is discussed.We proposed the empirical formula of velocity, pressure and the change of turbulent flow boundary layer on outlet bucket concave.According to the momentum principle,we have deduced the momentum integral equation full water depth boundary layer and using the element as control unit inside the boundary layer on concave surface of bucket.Combining with continuity equation,we have computed the boundary layer development on the bucket of a spillway.Compared with the field experimental data,the calculation results are available.Under polar coordinates,a mathematical model for simulating time-averaged flow characteristics in concave surface of bucket is established.The turbulent flow field on concave surface of bucket is calculated by SIMPLE method and this mathematical model.The flow velocity field,pressure field,distribution of turbulent kinetic energy, distribution of turbulent energy dissipating rate and distribution of shear stress are available.The calculation value is consistent with measured test data.展开更多
The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands ...The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands in the axial and radial directions simultaneously, and then, is subjected to the constraint of chamber wall, in axial direction mainly. The maximum axial speed of the cavity's head ranges from 240m/s to 280m/s. Some strong heat conduction and mass transmission effects can be found in the surface of Taylor cavity, where the plasma cools down and condenses as solid particles while the liquid vaporizes as gas. Compared the expansion processes of the cavities among the different discharge energies and the nozzle diameters, it can be seen that the expansion speed of the cavity is directly proportional to the discharge energy and inversely to the nozzle diameter, and the effect of the discharge energy is stronger than that of the nozzle diameter. A set of equations describing the expansion process of ablation plasma jet was derived under the assumption of momentum conservation. The calculated results by use of the equations coincide with the experimented results better.展开更多
文摘This paper will introduce experimental studies and numerical calculation on turbulent boundary layer of water flow along curved surface in our country in recent years.On the basis of the experimental studies,the effects of curvature and roughness on velocity distribution and pressure distribution and the change of turbulent flow boundary layer on overflow bucket concave surface is discussed.We proposed the empirical formula of velocity, pressure and the change of turbulent flow boundary layer on outlet bucket concave.According to the momentum principle,we have deduced the momentum integral equation full water depth boundary layer and using the element as control unit inside the boundary layer on concave surface of bucket.Combining with continuity equation,we have computed the boundary layer development on the bucket of a spillway.Compared with the field experimental data,the calculation results are available.Under polar coordinates,a mathematical model for simulating time-averaged flow characteristics in concave surface of bucket is established.The turbulent flow field on concave surface of bucket is calculated by SIMPLE method and this mathematical model.The flow velocity field,pressure field,distribution of turbulent kinetic energy, distribution of turbulent energy dissipating rate and distribution of shear stress are available.The calculation value is consistent with measured test data.
基金Sponsored by the National Nature Science Foundation of China (10302102)
文摘The expansion process of ablation plasma jet in liquid was experimentally investigated by using high speed digital camera. The sequential pictures show that, in the initial stage of the jet, the Taylor cavity expands in the axial and radial directions simultaneously, and then, is subjected to the constraint of chamber wall, in axial direction mainly. The maximum axial speed of the cavity's head ranges from 240m/s to 280m/s. Some strong heat conduction and mass transmission effects can be found in the surface of Taylor cavity, where the plasma cools down and condenses as solid particles while the liquid vaporizes as gas. Compared the expansion processes of the cavities among the different discharge energies and the nozzle diameters, it can be seen that the expansion speed of the cavity is directly proportional to the discharge energy and inversely to the nozzle diameter, and the effect of the discharge energy is stronger than that of the nozzle diameter. A set of equations describing the expansion process of ablation plasma jet was derived under the assumption of momentum conservation. The calculated results by use of the equations coincide with the experimented results better.
