The flow behavior in hydrocyclones is quite complex. In this study, the computational fluid dynamics (CFD) method was used to simulate the flow fields inside a hydrocyclone in order to investigate its separation efficiency. In the computational fluid dynamics study of hydrocyclones, the air-core dimension is a key to predicting the mass split between the underflow and overflow. In turn, the mass split influences the prediction of the size classification curve. Three models, the k − ε model, the Reynolds stress model (RSM) without considering the air-core, and the Reynolds stress turbulence model with the volume of fluid (VOF) multiphase model for simulating the air-core, were compared in terms of their predictions of velocity, axial and tangential velocity distributions, and separation proportion. The RSM with air-core simulation model, since it reproduces some detailed features of the turbulence and multiphase, clearly predicted the experimental data more closely than did the other two models.

A numerical study of the gas-liquid-solid multiphase flow in hydrocyclones is presented. Three models of turbulence, the RNG k-ε model, the Reynolds stress model and Large eddy simulation with the volume of fluid model (VOF) multiphase model for simulating air core are compared in order to predict axial and tangential velocity distributions. This presentation is mainly aimed at identifying an optimal method, used to study effective parameters, based on which, eventually, effect of inlet flow rate variations and body dimension variations such as underflow diameter, overflow diameter and cone angle on the separation performance and pressure drop are investigated. The results are then used in the simulation of particle flow described by the stochastic Lagrangian model. The results suggest that the predicted size classifications are approximately similar to those of RSM and LES methods. Predictions using the RSM model are found in agreement with experimental results with a marginal error within the range of 4 to 8%. Proceeding model validation, parametric studies have been carried out concerning the influence of velocity inlet, particle size and body dimension such as underflow and overflow diameter and cone angle. The predictions demonstrate that the flow fields in the hydrocyclones with different sizes and lengths are different, which yields different performances.

Purpose The effect of zirconium, zinc, calcium and rare earth group as the alloying elements on mechanical properties and corrosion behavior of magnesium alloys was investigated in the simulated body fluid. Design/methodology/approach Pure magnesium and the alloying elements were melted and zirconium was finally added to obtain different alloys. The castings were annealed and some samples were aged heat treated. X-ray fluorescence was used for the elemental analysis and LSV was used for electrochemical corrosion evaluations. Findings Results showed that corrosion resistance decreases with increasing zirconium content. The lowest corrosion rate was obtained for the samples containing 0.3% and 0.45% of Zr from annealed and aging heat-treated samples, respectively. Yield stress enhances with increasing the zirconium content and degrades by the aging heat treatment. Originality/value These alloys were studied for the first time. Effect of casting without using protective flux and vacuum furnaces. Effect of annealing at 440°C for 2 h and artificial aging at 200°C for 16 h. Alloy’s electrochemical behavior on the body’s simulation environment has been investigated. Improvement of mechanical properties after annealing heat treatment by high zirconium percentage.

Purpose The purpose of this study was to investigate the effect of electrolyte compounds on the anodizing process. Magnesium and its alloys have low corrosion resistance. Anodizing operation is performed to increase the corrosion resistance of magnesium. Anodizing solution compounds have a great effect on the oxide coating formed on the substrate. The effect of anodizing electrolyte composition on the corrosion behavior of magnesium was investigated in the simulated body fluid. Design/methodology/approach Three pure magnesium samples were anodized separately at 15 min, a constant voltage of 9 volts and room temperature. Three different solutions were used, which are the anodizing solution by the Harry A. Evangelides (HAE) method, the sodium hydroxide solution and the anodizing solution of the HAE method without potassium permanganate. Field emission scanning electron microscope (FE-SEM) was used to examine the surface of the anodized oxide layer and electrochemical impedance spectroscopy (EIS) was used for electrochemical corrosion evaluations. Findings The results of corrosion tests showed that the sample anodized in the solution without potassium permanganate has had the highest corrosion resistance. Also, microscopic images showed that the surface of the oxide layer of this sample had a uniform structure and is somewhat smooth. It seems that in the anodizing process by HAE method at 9 volts and for 15 min, the absence of potassium permanganate improves the corrosion resistance of magnesium. Also, anodizing in HAE solution gives more positive results than anodizing in sodium hydroxide solution. Originality/value The solution without potassium permanganate was studied for the first time and also the effect of these three anodizing electrolytes was compared together for the first time. Effect of anodizing at 15 min and constant voltage of 9 volts. Sample’s electrochemical behavior in the body's simulation environment has been investigated. Improvement of electrochemical properties in the solution of the HAE method without potassium permanganate.

The flow behavior in hydrocyclones is quite complex. The computational fluid dynamics method was used to simulate the flow fields inside a hydrocyclone in order to investigate its separation efficiency. In the computational fluid dynamics study of hydrocyclones, the air-core dimension is a key to predicting the mass split between the underflow and overflow. In turn, the mass split influences the prediction of the size classification curve. Generally in hydrocyclone simulations, assuming low particle volume fractions, the discrete phase effects on the continuous phase have been excluded; therefore, one-way coupling method has been used. Due to high particle consistencies, regions in some cases, especially in underflow areas, excluding discrete phase effects on continuous phase may be ineligible. In this study for an example case by consisting discrete phase effects and using two-way coupling method, simulation accuracy noticeably has been improved. Three models, the k−ε model, the Reynolds stress model (RSM) without considering air core, and Reynolds stress turbulence model with volume of fluid multiphase model for simulating air core, were compared for the predictions of velocity, axial, and tangential velocity distributions and separation proportion. Results by the RSM with air-core simulation and two-way coupling model, since it produces some detailed features of the turbulence and discrete phase mode effects, are clearly closer in predicting the experimental data than the other two.