To solve the problem of finishing the twist blade surface of an impeller, the five-axis numerically controlled electrochemical contour evolution grinding （NC-ECCEG） is studied. Over-cutting errors of NC-ECCEG of the...To solve the problem of finishing the twist blade surface of an impeller, the five-axis numerically controlled electrochemical contour evolution grinding （NC-ECCEG） is studied. Over-cutting errors of NC-ECCEG of the twist blade surface generated by parallel lines are analyzed. The formula for calculating the over-cutting error is deduced. The method for eliminating the over-cutting error is used in the conical grinding wheel and the combined five-axis linkage NC-ECCEG system. The structure and the movement of the NC-ECCEG machine tool,the combined multi-axis NC system and its linkage control technology are introduced. Further, the mathematical model of the NC-ECCEG unparallel-ruled surface is established. An auto-programming system on five-axis NGECCEG is developed to grind the impeller. The machining efficiency of NC-ECCEG increases more than 12 times than that of manual polishing operations.展开更多
The dissipation rate of turbulent kinetic energy （ ε ） is the key process parameters for mixing in surface aerators. At constant dynamic variables （rotational speed）, ε is greatly affected by the geometric param...The dissipation rate of turbulent kinetic energy （ ε ） is the key process parameters for mixing in surface aerators. At constant dynamic variables （rotational speed）, ε is greatly affected by the geometric parameters, such as impeller diameter, cross-sectional area of the tank, liquid height, rotor blade length and immersion height. By doing numerical computation by visimix, present work analyzes the effect of non-dimensional （which is non-dimensionalized through rotor diameter） geometric parameters on ε. With an increase in liquid height, there is an increase in the case of energy dissipation. In the case of tank area and blade length, it is vice versa. Energy dissipation is not affected by the variation in immersion height of the impeller.展开更多
文摘To solve the problem of finishing the twist blade surface of an impeller, the five-axis numerically controlled electrochemical contour evolution grinding （NC-ECCEG） is studied. Over-cutting errors of NC-ECCEG of the twist blade surface generated by parallel lines are analyzed. The formula for calculating the over-cutting error is deduced. The method for eliminating the over-cutting error is used in the conical grinding wheel and the combined five-axis linkage NC-ECCEG system. The structure and the movement of the NC-ECCEG machine tool,the combined multi-axis NC system and its linkage control technology are introduced. Further, the mathematical model of the NC-ECCEG unparallel-ruled surface is established. An auto-programming system on five-axis NGECCEG is developed to grind the impeller. The machining efficiency of NC-ECCEG increases more than 12 times than that of manual polishing operations.
文摘The dissipation rate of turbulent kinetic energy （ ε ） is the key process parameters for mixing in surface aerators. At constant dynamic variables （rotational speed）, ε is greatly affected by the geometric parameters, such as impeller diameter, cross-sectional area of the tank, liquid height, rotor blade length and immersion height. By doing numerical computation by visimix, present work analyzes the effect of non-dimensional （which is non-dimensionalized through rotor diameter） geometric parameters on ε. With an increase in liquid height, there is an increase in the case of energy dissipation. In the case of tank area and blade length, it is vice versa. Energy dissipation is not affected by the variation in immersion height of the impeller.
