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Search Results: 1 - 10 of 819 matches for " rotating cylinder "
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Rotating Variable-Thickness Inhomogeneous Cylinders: Part II—Viscoelastic Solutions and Applications  [PDF]
Ashraf M. Zenkour
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.16064
Abstract: Analytical solutions for the rotating variable-thickness inhomogeneous, orthotropic, hollow cylinders under plane strain assumption are developed in Part I of this paper. The extensions of these solutions to the viscoelastic case are discussed here. The method of effective moduli and Illyushin's approximation method are used for this purpose. The rotating fiber-reinforced viscoelastic homogeneous isotropic hollow cylinders with uniform thickness are obtained as special cases of the studied problem. Numerical application examples are given for the dimensionless displacement of and stresses in the different cylinders. The influences of time, constitutive parameter and elastic properties on the stresses and displacement are investigated.
Dimensional and Mechanical Similarity Analysis of the Flow in Rotating Liquid Film Reactor  [PDF]
Xue Li, Lanxi Xu, Jingjing Zhang, Wanli Lan
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32004
Abstract:  

A rotating liquid film reactor (RLFR) is a device of two coaxial rotating conical cylinders with the inner cone rotating and the outer one stationary. A complete mathematical model for the flow between the conical cylinders is built and a dimensional analysis is carried out. It is proved that at each point of the flow field the dimensionless pressure and velocity of the flow are determined by parameters: Reynolds number (Re), aspect ratio (Γ), radius ratio (η) and wall inclination angle (α). Furthermore, a sufficient and a necessary condition are derived from mechanical similarity between RLFR and a manufacturing equipment geometrically similar to RLFR. Finally, a numerical simulation for the distribution of pressure and velocity is performed. The results may provide a theoretical basis for experiment method and numerical simulation of the flow in a RLFR-like device.

Evaluation of Corrosion Behavior of Copper in Chloride Media Using Electrochemical Impedance Spectroscopy (EIS)
Nagiub,A.M.;
Portugaliae Electrochimica Acta , 2005,
Abstract: the corrosion behavior of pure copper rotating cylinder electrode (rce) exposed to 3% nacl or artificial seawater prepared as v?t??nen nine salt solution (vnss) has been studied using electrochemical impedance spectroscopy (eis) and polarization techniques. eis experiments for copper rce were carried out at different rotation rate from 0 rpm to 1600 rpm. polarization resistance (rp) values were obtained from both eis and polarization experiments. excellent agreement between impedance and polarization data is observed. rce experiments demonstrated that ecorr and corrosion rate for copper depend linearly on rotation speed r0.7. the results obtained showed that eis is a powerful electrochemical method to follow the change of corrosion mechanisms.
Effect of Non-aqueous Solvents on the Rate of Production of Copper Powder from Copper Sulphate Solution by Cementation on Stationary Zinc Sheet and Rotating Zinc Cylinder
Taha,A.A.;
Portugaliae Electrochimica Acta , 2004,
Abstract: the rate of copper ii/zinc cementation from copper sulphate solutions in the absence and in the presence of methanol (ch3oh) and dimethyl sulphoxide (dmso) has been studied and the reaction was found to follow first-order kinetics. the influence of several parameters on the course of the reaction, such as cylinder rotation speed, initial concentration of cu2+ ions, temperature and concentration of organic solvent, was investigated. in the case of ch3oh, rotating zinc cylinder was used, while in the presence of dmso stationary zinc sheet and rotating zinc cylinder were used. it was found that (1) the percentage inhibition caused by methanol ranged from 10.70 to 58.38 depending on the concentration of the alcohol used; (2) the rate of cementation in the presence of dmso using rotating zinc cylinder > the rate of cementation in the presence of dmso using stationary zinc sheet; (3) the rate of cementation on zinc cylinder in the presence of dmso < the rate of cementation in the presence of ch3oh. different reaction conditions, and the physical properties of solutions are studied to obtain dimensionless correlation among all these parameters. thermodynamic parameters δs*, δh* and δg* were studied.
Effect of Non-aqueous Solvents on the Rate of Production of Copper Powder from Copper Sulphate Solution by Cementation on Stationary Zinc Sheet and Rotating Zinc Cylinder
A.A. Taha
Portugaliae Electrochimica Acta , 2004,
Abstract: The rate of copper II/zinc cementation from copper sulphate solutions in the absence and in the presence of methanol (CH3OH) and dimethyl sulphoxide (DMSO) has been studied and the reaction was found to follow first-order kinetics. The influence of several parameters on the course of the reaction, such as cylinder rotation speed, initial concentration of Cu2+ ions, temperature and concentration of organic solvent, was investigated. In the case of CH3OH, rotating zinc cylinder was used, while in the presence of DMSO stationary zinc sheet and rotating zinc cylinder were used. It was found that (1) the percentage inhibition caused by methanol ranged from 10.70 to 58.38 depending on the concentration of the alcohol used; (2) the rate of cementation in the presence of DMSO using rotating zinc cylinder > the rate of cementation in the presence of DMSO using stationary zinc sheet; (3) the rate of cementation on zinc cylinder in the presence of DMSO < the rate of cementation in the presence of CH3OH. Different reaction conditions, and the physical properties of solutions are studied to obtain dimensionless correlation among all these parameters. Thermodynamic parameters ΔS*, ΔH* and ΔG* were studied.
Evaluation of Corrosion Behavior of Copper in Chloride Media Using Electrochemical Impedance Spectroscopy (EIS)
A.M. Nagiub
Portugaliae Electrochimica Acta , 2005,
Abstract: The corrosion behavior of pure copper rotating cylinder electrode (RCE) exposed to 3% NaCl or artificial seawater prepared as V t nen nine salt solution (VNSS) has been studied using electrochemical impedance spectroscopy (EIS) and polarization techniques. EIS experiments for copper RCE were carried out at different rotation rate from 0 rpm to 1600 rpm. Polarization resistance (Rp) values were obtained from both EIS and polarization experiments. Excellent agreement between impedance and polarization data is observed. RCE experiments demonstrated that Ecorr and corrosion rate for copper depend linearly on rotation speed r0.7. The results obtained showed that EIS is a powerful electrochemical method to follow the change of corrosion mechanisms.
Determination of Mild Steel Corrosion Rate under Turbulent Flow in Highly Acidic Solution
A.Y. Musa,A.A.H. Kadhum,A.B. Mohamad,M.S. Takriff
Journal of Applied Sciences , 2011,
Abstract: The corrosion rate for mild steel in 2.5 M H2SO4 at 30C for different flow velocities was determined. Electrochemical techniques such as Tafel polarization and electrochemical impedance spectroscopy (EIS) were carried out to study the effects of flow velocity on corrosion rate of mild steel. The turbulent conditions experiments were simulated using rotating cylinder electrode (RCE). Results obtained from Tafel polarization and EIS were in good agreement. The study revealed that the mild steel corrosion rate decreased with increases in flow velocity due to improvement of the passivation by an increase of the oxygen supply. Corrosion potentials were shafted toward the cathodic values and the magnitude of the impedance was rose with flow velocities.
Electrowinning of Copper Using Rotating Cylinder Electrode Utilizing Lead Anode  [PDF]
Hesham Soliman, Ahmed Abd El-Moneim
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.34039
Abstract: The effect of lead anode, rotating cylinder electrode (RCE), amount of 1,2-dihydroxypropane (12-DHP), temperature and rotation on the electrowinning of copper from low concentration acidified copper sulphate solution has been investigated. Copper powder was electrodeposited onto RCE that made of pure copper. From cyclic voltammetry experiments, an empirical parameter called the departure percent, S, was obtained which may represent the stability of the organic additive in the given medium and under the experimental conditions. The inhibition percentage, P, was 0.00 - 89.91% depending on the experimental variables. P was affected by temperature and mole fraction of 12-DHP, while rotation did not show any influence on it. Values of activation energy of electrodeposition process, Ea, were found to be less than 28 kJ mol-1 indicating diffusion controlled process. The overall mass transfer correlations under the present conditions have been computed using the dimensional analysis method. The data were valid for 90 < Sh < 1098, 737 < Sc < 59284 and 271 < Re < 7046 and the results agreed with the previous studies of mass transfer to rotating cylinders in turbulent flow regimes. The effect of time, content of 12-DHP, temperature and the speed of rotation on the morphological changes of the electrodeposited copper powder as well as deposits composition and crystallite size have been studied. Various crystallite sizes ranged 7.1 nm - 250.6 nm were obtained and characterized by EDS and XRD. Different topographs proved that the rate of copper electrodeposition increased by increasing deposition time, temperature and the speed of rotation. Also, they proved that the deposition rate decreased by adding 12-DHP to the solution. Therefore, the results obtained by SEM supported those achieved by measuring the limiting current density and follow the normal manner when organic solvents were added to the electrodeposition bath.
Numerical simulations of flows over a rotating circular cylinder using the immersed boundary method
Silva, Alice Rosa da;Silveira Neto, Aristeu da;Lima, Antonio Marcos G. de;Rade, Domingos Alves;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2011, DOI: 10.1590/S1678-58782011000100014
Abstract: in this paper, numerical simulations of incompressible flows around rotating circular cylinders have been performed. the two-dimensional navier-stokes equations are solved by using a cartesian non-uniform grid. the immersed boundary method (ibm) with the virtual physical model (vpm) was used in order to model the presence of the circular cylinder in the flow. the fractional time step method was used to coupling the pressure and velocity fields. the simulations were carried out for reynolds numbers equals to 60, 100 and 200 for different specific rotations. the effects of rotation on flow characteristics and fluctuating forces were investigated. the strouhal number, obtained by performing the fast fourier transform (fft) of the temporal distribution of the lift coefficient, and the pressure coefficients, were also been calculated. vorticity contours are presented considering different values of the reynolds number and specific rotation. the numerical results obtained are compared to those obtained by other authors and the usefulness of the numerical methodology composed by the combination of the ibm with the vpm to simulate flows in the presence of mobile bodies is highlighted.
Modelado y Simulación del Secado de Textiles Delgados Mediante un Cilindro Calentado por Inducción Eléctrica
Franceschi,Katiuska; Pérez,Sergio; Ni?o,Zulay; Magarelli,Donato;
Información tecnológica , 2008, DOI: 10.4067/S0718-07642008000400006
Abstract: the development of a mathematical model for the drying of thin fabrics using a rotatory cylinder heated by electrical induction is proposed in this work. firstly, the thermal dynamics of the cylinder is studied using the equations that describe the energy transfer during the cooling and heating steps of the cylinder. after that, the model determines the temperature for the cylinder, the humidity and the temperature in the drying zone. the values obtained for these variables from the mathematical model were validated with experimental data at different operating conditions. the results show small deviations between predicted values and experimental data, with deviations lower than 10%.
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