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
The thixocasting process was chosen to produce the impellers as it is capable of producing castings with extremely high internal quality.Slugs cut from the DC cast bars are re-heated to the semi-solid casting temperat...The thixocasting process was chosen to produce the impellers as it is capable of producing castings with extremely high internal quality.Slugs cut from the DC cast bars are re-heated to the semi-solid casting temperature, and a specially-designed runner and gating system is used to prevent oxide from the surface of the slugs from becoming incorporated into the impeller.The technology used to produce the semi-solid impellers is described in detail.The semi-solid cast impellers, produced from an Al-Si-Mg-Cu alloy, are heat treated to the T6 temper.Results from testing are presented demonstrating that the impellers are free of porosity and other internal defects.Both mechanical property and fatigue data are presented showing that the semi-solid impellers have better properties than impellers produced by conventional casting and similar properties to forged and machined impellers.A short study is also described which identified suitable processing parameters to minimize hot tearing in the complex-shaped turbocharger impellers semi-solid cast from alloy 201.The surfaces of the impellers were examined using penetrant testing, and the results of modifying processing parameters on the propensity for surface cracking are presented.An aging study was performed to identify optimum mechanical strength.展开更多
Some effective parameters on the copper extraction from Kiire chalcopyrite concentrate were optimized by using response surface methodology （RSM）. Experiments designed by RSM were carried out in the presence of ammo...Some effective parameters on the copper extraction from Kiire chalcopyrite concentrate were optimized by using response surface methodology （RSM）. Experiments designed by RSM were carried out in the presence of ammonium persulfate （APS） and different types of impeller in an autoclave system. Ammonium persulfate concentration and leaching temperature were defined numerically and three types of impellers were defined categorically as independent variables using experimental design software. The optimum condition for copper extraction from the chalcopyrite concentrate is found to be ammonium persulfate concentration of 277.77 kg/m3, leaching temperature of 389.98 K and wheel type of impeller. The proposed model equation using RSM has shown good agreement with the experimental data, with correlation coefficients R2 and RaZaj for the model as 0.89 and 0.84, respectively.展开更多
Compressible boundary layers stability on blade cascade suction surface was discussed by wind tunnel experiment and numerical solution. Three dimensional disturbance wave Parabolized Stability Equations (PSE) of ortho...Compressible boundary layers stability on blade cascade suction surface was discussed by wind tunnel experiment and numerical solution. Three dimensional disturbance wave Parabolized Stability Equations (PSE) of orthogonal Curvilinear Coordinates in compressible flow was deducted. The surface pressure of blade in wind tunnel experiment was measured. The Falkner-Skan equation was solved under the boundary conditions of experiment result, and velocity, pressure and temperature of average flow were obtained. Substituted this result for discretization of the PSE Eigenvalue Problem, the stability problem can be solved.展开更多
In order to shorten the design period, the paper describes a new optimization strategy for computationally expensive design optimization of turbomachinery, combined with design of experiment (DOE), response surface mo...In order to shorten the design period, the paper describes a new optimization strategy for computationally expensive design optimization of turbomachinery, combined with design of experiment (DOE), response surface models (RSM), genetic algorithm (GA) and a 3-D Navier-Stokes solver(Numeca Fine). Data points for response evaluations were selected by improved distributed hypercube sampling (IHS) and the 3-D Navier-Stokes analysis was carried out at these sample points. The quadratic response surface model was used to approximate the relationships between the design variables and flow parameters. To maximize the adiabatic efficiency, the genetic algorithm was applied to the response surface model to perform global optimization to achieve the optimum design of NASA Stage 35. An optimum leading edge line was found, which produced a new 3-D rotor blade combined with sweep and lean, and a new stator one with skew. It is concluded that the proposed strategy can provide a reliable method for design optimization of turbomachinery blades at reasonable computing cost.展开更多
This paper describes the numerical study on film cooling effectiveness and aerodynamic loss due to coolant and main stream mixing for a turbine guide vane. The effects of blowing ratio, mainstream Mach number, surface...This paper describes the numerical study on film cooling effectiveness and aerodynamic loss due to coolant and main stream mixing for a turbine guide vane. The effects of blowing ratio, mainstream Mach number, surface curvature on the cooling effectiveness and mixing loss were studied and discussed. The numerical results show that the distributions of film cooling effectiveness on the suction surface and pressure surface at the same blowing ratio(BR) are different due to local surface curvature and pressure gradient. The aerodynamic loss features for film holes on the pressure surface are also different from film holes on the suction surface.展开更多
This paper presents a wind tunnel experiment for the evaluation of energy performance and aerodynamic forces acting on a small straight-bladed vertical axis wind turbine(VAWT) depending on several values of tip speed ...This paper presents a wind tunnel experiment for the evaluation of energy performance and aerodynamic forces acting on a small straight-bladed vertical axis wind turbine(VAWT) depending on several values of tip speed ratio. In the present study, the wind turbine is a four-bladed VAWT. The test airfoil of blade is symmetry airfoil(NACA0021) with 32 pressure ports used for the pressure measurements on blade surface. Based on the pressure distributions which are acted on the surface of rotor blade measured during rotation by multiport pressure-scanner mounted on a hub, the power, tangential force, lift and drag coefficients which are obtained by pressure distribution are discussed as a function of azimuthally position. And then, the loads which are applied to the entire wind turbine are compared with the experiment data of pressure distribution. As a result, it is clarified that aerodynamic forces take maximum value when the blade is moving to upstream side, and become small and smooth at downstream side. The power and torque coefficients which are based on the pressure distribution are larger than that by torque meter.展开更多
This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 （known in QNET network as open test case SE1050）. The primary goal was to assess the influence of the...This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 （known in QNET network as open test case SE1050）. The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic （M2 = 0.8） and at transonic （M2 = 1.2） regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenFOAM and in-house code. Analyses of experimental data and CFD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CFD and experiments agree reasonably well.展开更多
The concept of using blade slotting to suppress the large boundary layer separation of high aerodynamic loading low pressure turbine profile has been developed in Part 1.Calculated results highlight the inability perf...The concept of using blade slotting to suppress the large boundary layer separation of high aerodynamic loading low pressure turbine profile has been developed in Part 1.Calculated results highlight the inability performance accompanied with un-proper blade slotting at high Reynolds number,blade slotting optimization seems like compulsory.Meanwhile,to further dignify the rational for use of blade slotting,slotting position and its geometry needed to be optimized.Comparison of different slotting scheme calculation results promised that blade slotting parameter like outlet angle and outlet position are the most important parameters which must be investigated to satisfy the design purpose.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.
文摘The thixocasting process was chosen to produce the impellers as it is capable of producing castings with extremely high internal quality.Slugs cut from the DC cast bars are re-heated to the semi-solid casting temperature, and a specially-designed runner and gating system is used to prevent oxide from the surface of the slugs from becoming incorporated into the impeller.The technology used to produce the semi-solid impellers is described in detail.The semi-solid cast impellers, produced from an Al-Si-Mg-Cu alloy, are heat treated to the T6 temper.Results from testing are presented demonstrating that the impellers are free of porosity and other internal defects.Both mechanical property and fatigue data are presented showing that the semi-solid impellers have better properties than impellers produced by conventional casting and similar properties to forged and machined impellers.A short study is also described which identified suitable processing parameters to minimize hot tearing in the complex-shaped turbocharger impellers semi-solid cast from alloy 201.The surfaces of the impellers were examined using penetrant testing, and the results of modifying processing parameters on the propensity for surface cracking are presented.An aging study was performed to identify optimum mechanical strength.
基金supported by the TUBITAK(Scientific and Technological Research Council of Turkey) under the Project No:106M177
文摘Some effective parameters on the copper extraction from Kiire chalcopyrite concentrate were optimized by using response surface methodology （RSM）. Experiments designed by RSM were carried out in the presence of ammonium persulfate （APS） and different types of impeller in an autoclave system. Ammonium persulfate concentration and leaching temperature were defined numerically and three types of impellers were defined categorically as independent variables using experimental design software. The optimum condition for copper extraction from the chalcopyrite concentrate is found to be ammonium persulfate concentration of 277.77 kg/m3, leaching temperature of 389.98 K and wheel type of impeller. The proposed model equation using RSM has shown good agreement with the experimental data, with correlation coefficients R2 and RaZaj for the model as 0.89 and 0.84, respectively.
文摘Compressible boundary layers stability on blade cascade suction surface was discussed by wind tunnel experiment and numerical solution. Three dimensional disturbance wave Parabolized Stability Equations (PSE) of orthogonal Curvilinear Coordinates in compressible flow was deducted. The surface pressure of blade in wind tunnel experiment was measured. The Falkner-Skan equation was solved under the boundary conditions of experiment result, and velocity, pressure and temperature of average flow were obtained. Substituted this result for discretization of the PSE Eigenvalue Problem, the stability problem can be solved.
文摘In order to shorten the design period, the paper describes a new optimization strategy for computationally expensive design optimization of turbomachinery, combined with design of experiment (DOE), response surface models (RSM), genetic algorithm (GA) and a 3-D Navier-Stokes solver(Numeca Fine). Data points for response evaluations were selected by improved distributed hypercube sampling (IHS) and the 3-D Navier-Stokes analysis was carried out at these sample points. The quadratic response surface model was used to approximate the relationships between the design variables and flow parameters. To maximize the adiabatic efficiency, the genetic algorithm was applied to the response surface model to perform global optimization to achieve the optimum design of NASA Stage 35. An optimum leading edge line was found, which produced a new 3-D rotor blade combined with sweep and lean, and a new stator one with skew. It is concluded that the proposed strategy can provide a reliable method for design optimization of turbomachinery blades at reasonable computing cost.
基金financially supported by the National Natural Science Foundation of China through Grant No.51336007
文摘This paper describes the numerical study on film cooling effectiveness and aerodynamic loss due to coolant and main stream mixing for a turbine guide vane. The effects of blowing ratio, mainstream Mach number, surface curvature on the cooling effectiveness and mixing loss were studied and discussed. The numerical results show that the distributions of film cooling effectiveness on the suction surface and pressure surface at the same blowing ratio(BR) are different due to local surface curvature and pressure gradient. The aerodynamic loss features for film holes on the pressure surface are also different from film holes on the suction surface.
文摘This paper presents a wind tunnel experiment for the evaluation of energy performance and aerodynamic forces acting on a small straight-bladed vertical axis wind turbine(VAWT) depending on several values of tip speed ratio. In the present study, the wind turbine is a four-bladed VAWT. The test airfoil of blade is symmetry airfoil(NACA0021) with 32 pressure ports used for the pressure measurements on blade surface. Based on the pressure distributions which are acted on the surface of rotor blade measured during rotation by multiport pressure-scanner mounted on a hub, the power, tangential force, lift and drag coefficients which are obtained by pressure distribution are discussed as a function of azimuthally position. And then, the loads which are applied to the entire wind turbine are compared with the experiment data of pressure distribution. As a result, it is clarified that aerodynamic forces take maximum value when the blade is moving to upstream side, and become small and smooth at downstream side. The power and torque coefficients which are based on the pressure distribution are larger than that by torque meter.
基金supported by the Czech Science Foundation under the grant No. GAP 101/10/1329
文摘This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 （known in QNET network as open test case SE1050）. The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic （M2 = 0.8） and at transonic （M2 = 1.2） regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenFOAM and in-house code. Analyses of experimental data and CFD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CFD and experiments agree reasonably well.
基金provided by the Supercomputing Center of Chinese Academy of Sciences and the sponsorship of National Natural Science Foundation of China
文摘The concept of using blade slotting to suppress the large boundary layer separation of high aerodynamic loading low pressure turbine profile has been developed in Part 1.Calculated results highlight the inability performance accompanied with un-proper blade slotting at high Reynolds number,blade slotting optimization seems like compulsory.Meanwhile,to further dignify the rational for use of blade slotting,slotting position and its geometry needed to be optimized.Comparison of different slotting scheme calculation results promised that blade slotting parameter like outlet angle and outlet position are the most important parameters which must be investigated to satisfy the design purpose.
