Toward a Full Simulation of the Basic Oxygen Furnace: Deformation of the Bath Free Surface and Coupled Transfer Processes Associated with the Post-Combustion in the Gas Region

The present article treats different phenomena taking place in a steelmaking converter through the development of two separate models. The first model describes the cavity produced at the free surface of the metal bath by the high-speed impinging oxygen jet. The model is based on a zonal approach, where gas compressibility effects are taken into account only in the high velocity jet region, while elsewhere the gas is treated as incompressible. The volume of fluid (VOF) method is employed to follow the deformation of the bath free surface. Calculations are presented for two- and three-phase systems and compared against experimental data obtained in a cold model experiment presented in the literature. The influence on the size and shape of the cavity of various parameters and models (including the jet inlet boundary conditions, the VOF advection scheme, and the turbulence model) is studied. Next, the model is used to simulate the interaction of a supersonic oxygen jet with the surface of a liquid steel bath in a pilot-scale converter. The second model concentrates on fluid flow, heat transfer, and the post-combustion reaction in the gas phase above the metal bath. The model uses the simple chemical reaction scheme approach to describe the transport of the chemical species and takes into account the consumption of oxygen by the bath and thermal radiative transfer. The model predictions are in reasonable agreement with measurements collected in a laboratory experiment and in a pilot-scale furnace.     

Analysis of fluid–elastic-structure interactions in an impinging jet with a dynamic 3D-PTV and non-contact 6D-motion tracking system

Measurements on pulsed impinging jets with 3D-particle tracking velocimetry (3D-PTV) system and 6-degree-of-freedom (DOF)-motion tracking system were carried out. Pulsed round jets were impinged on an elastic plate and the flow field near the plate was measured with a 3D-PTV system while the motions of the flexible plate was measured with 6D-motion tracking system. The measurement system consists of four cameras, light sources (Nd-Yag laser, Ar-ion laser, Black lamp) and a host computer. The nozzle diameter is D = 15 mm and two major experiments have been carried out for the cases of the distances between the nozzle tip to the elastic wall are z/D = 2.3 and 6.0. The pulsed jets were controlled by a solenoid valve and were impinged onto an elastic plate (material: silicon, diameter: 350 mm, thickness: 0.5 mm, hardness: 15). The measurement system was synchronized with the valve opening time. The Reynolds numbers were 20,000 and 24,000 when the jets were impinged with the volume velocities. In the first experiments a macroscopic interprets on the flow–structure interactions (FSI) was made using three-dimensional vector fields of the flow and three-dimensional displacements of the elastic plate. In the second experiments a microscopic interprets on the FSI was made using two-dimensional velocity vectors and three-dimensional displacements of the elastic plate. Experimental results showed that the elastic plate moved slightly to the opposite direction of the jet direction at the time of valve opening. It has been shown that the vortices travelling over the surface of the wall made the elastic wall distorted locally.     

Crack coalescence morphology in rock-like material under compression

This paper uses peridynamic simulations to determine the extent of coalescing damage and identify the underlying causes. The basic crack types and crack coalescence patterns in specimens with a flaw pair under uniaxial compression are systematically investigated. Various crack types including horsetail cracks, anti-wing cracks, and tensile wing cracks are successfully observed and the coalescence sequences are identified. By varying angles, six crack coalescence categories with respect to the overlapping ratios provide insightful information of different crack growths and indicate various cracking modes underlying various coalescence patterns. The arrangement of the flaw pair strongly influences the crack initiation position and trajectories, allowing for different coalescence morphologies. Coalescence formed by two internal tensile wing cracks, or transfixion, shows unbroken crack segments with a further loading, along with growing shear cracks until failure. In contrast, after the coalescence is formed through two horsetail cracks, the interior of the rhombic shape gets deformed with further loading. The peridynamic code adopted in this research can provide realistic simulation results and help researchers to conduct expanded tests as well as to enhance understanding the fracture of rock-like material.     

Development of a concentration measurement technique for steady state solid-liquid mixing using a neural network

A measurement technique that can measure the concentration of the solid particles in liquid flow was developed.The measurement system consists of a color camera and three LCD displays.The solid particles were put at the bottom of a cylindrical mixing tank in which JetA1 oil was filled.Transient mixing of the solid particles was performed by rotating a propeller type agitator with three different rotation speed(500,600,700 r/min).Mixing state was visualized by the LCD displays and a color camcorder.The color intensity of the glass particles changes with their concentration.The color information was decoded into three principle colors R,G,and B so that,the calibration curve of color-to-concentration was performed using these information.A neural network was used for this calibration.The transient concentration field of the solid particles was quantitatively visualized.     

Development and ejection behavior of different material-based electrostatic ink-jet heads

There has been growing interests in direct patterning of metallic contents on the surface of the substrate without including complex steps of the microfabrication lithography process. The direct fabrication process using electrostatic ink-jet printing can be expected to be a powerful tool for both nanotechnology research and applications such as microelectronics. The droplet ejection voltage, meniscus, cone-jet behavior, and counter electrode distance depends on the ink properties such as surface tension, viscosity, and percentage of metallic pigments. In this paper, 2-μm level needle-type electrostatic head designs for contact-less fabrication of printed electronics, composed of differently treated surface materials, have been studied and analyzed. The electrostatically actuated ink-jet heads were tested and compared for low power and high resolution on ink containing metallic nano-particle particles as pigments. The two laboratory-fabricated discrete and electrostatically actuated ink-jet heads, one made by poly di-methyl siloxane modeling process and other through micro-electrical discharge machine techniques, were compared, and their orifice outlet surface (hydrophobic and hydrophilic) condition influence has been discussed. The paper also investigates different dripping behaviors of metallic ink under the influence of counter electrode distance, voltages, and materials. The observation of droplet ejection with high-speed camera revealed that in the case of hydrophobic head, better meniscus shape and ejection was achieved even at low voltage compared to the hydrophilic head. It was also found that the less flow rate is required in hydrophobic head. Printing characteristic of the hydrophilic nozzle head was also compared with the hydrophobic head on PET substrate.     

Properties and consolidation of nanocrystalline WSi2-SiC composite from mechanically activated powders by pulsed current activated combustion synthesis

Dense nanostructured WSi₂-SiC composite was synthesized by pulsed current activated combustion synthesis method within 2 min in one step from mechanically activated powders of WC and 3Si. Simultaneous combustion synthesis and consolidation were accomplished under the combined effects of a pulsed current and mechanical pressure. Highly dense WSi₂-SiC with relative density of up to 99.8% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. The average grain size and mechanical properties of the composite were investigated.     

Framework for developing a static strength test for measuring deformation resistance of asphalt concrete mixtures

This study deals with a strength property which is showing high correlation with rutting resistance of asphalt mixtures. The test procedure was developed by applying a load to the compacted asphalt samples and calculating the strength by using the deformation of the mixture at the failure point. To evaluate the validity of this test, various mixtures were prepared with two aggregates and seven binders using four loading head types at the loading speed of 50.8 mm/min at 60 °C. Maximum load and deformation were recorded for each test and deformation strength, S_D, was calculated using a newly developed equation. For the same mixture, wheel tracking test was performed and two rut parameters, depth of rut and dynamic stability were obtained. The relationship between S_D and rut parameters was evaluated using regression analyses. In most cases, R² values were found to be over 0.9. This test procedure is still under development; however, current results indicate that it might be a simple test to predict the deformation resistance of asphalt mixtures at high temperatures.     

Fuzzy decoupling to reduce propagation of tension disturbances in roll-to-roll system

Control of web tension is crucial for maintaining quality of products processed on roll-to-roll (R2R) system. An R2R system can be divided into different tension spans which interact with each other. But converting industries tend to neglect these interactions and use decentralized single-input–single-output (SISO) control approaches to deal with tension control. Multi-input–multi-output approaches have been reported in literatures but are practically not in use. Interaction between the various tension spans is unavoidable as they are all connected by a single web. Disturbances produced in a span tend to travel further downstream along the direction of web travel. When the number of spans is less or the disturbance amplitudes are small, this does not present a big challenge and simple SISO control is sufficient. But when the amplitudes of disturbances produced in processing is large—as is the case with printed electronics—or the number of spans is large or both, then the interactions cannot be neglected. R2R-based offset printers have the potential for mass production of precision-printed electronics. In this paper, a fuzzy logic-based hybrid approach has been followed that specifically targets the printed electronics industry and this method considerably reduces the interactions. The algorithm has been designed such that it takes information from previous span to reduce the propagation of tension disturbances to the given span. This has been achieved through online computation of correlation coefficient and reducing the interaction through fuzzy feedback control.