To control the film thickness of zinc in the process of continuous hot-dip galvanizing, it is known from the early days that the gas wiping through an air knife is the most effective one. The gas wiping using in galva...To control the film thickness of zinc in the process of continuous hot-dip galvanizing, it is known from the early days that the gas wiping through an air knife is the most effective one. The gas wiping using in galvanizing process brings about a problem of splashing from the strip edge for a certain high speed of coating. So, in the present study, the effects of the deflection angle of Coanda nozzle on jet structure and the distribution of impinging pres- sure at the plate surface are investigated numerically and experimentally. In numerical analysis, the governing equations consisted of three-dimensional time dependent full Navier-Stokes equations, standard k-ε turbulence model to solve turbulent stTess and so on are employed. In experiment, 16 channel pressure scanning valve and 3-axis auto traversing unit are used to measure the impinging pressure at the strip surface. As a result, it is found that the smaller the deflection angle for the same nozzle slit of air knife is, the larger the impinging pressure is. To reduce the size of separation bubble and to enhance the cutting ability, it is recommendable to use an air knife with the Coanda nozzle.展开更多
Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall sl...Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall slope parameter and analytical expressions are derived for average velocity and stream function using Saffman slip condition. The effects of var ious relevant parameters on average velocity and stream line pattern have been studied. It is found that average velocity increases with slip and decreases with permeability and magnetic parameter.展开更多
文摘To control the film thickness of zinc in the process of continuous hot-dip galvanizing, it is known from the early days that the gas wiping through an air knife is the most effective one. The gas wiping using in galvanizing process brings about a problem of splashing from the strip edge for a certain high speed of coating. So, in the present study, the effects of the deflection angle of Coanda nozzle on jet structure and the distribution of impinging pres- sure at the plate surface are investigated numerically and experimentally. In numerical analysis, the governing equations consisted of three-dimensional time dependent full Navier-Stokes equations, standard k-ε turbulence model to solve turbulent stTess and so on are employed. In experiment, 16 channel pressure scanning valve and 3-axis auto traversing unit are used to measure the impinging pressure at the strip surface. As a result, it is found that the smaller the deflection angle for the same nozzle slit of air knife is, the larger the impinging pressure is. To reduce the size of separation bubble and to enhance the cutting ability, it is recommendable to use an air knife with the Coanda nozzle.
文摘Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall slope parameter and analytical expressions are derived for average velocity and stream function using Saffman slip condition. The effects of var ious relevant parameters on average velocity and stream line pattern have been studied. It is found that average velocity increases with slip and decreases with permeability and magnetic parameter.
