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Numerical Study of Arc Exposure about Water-Panel Overheating in an Electric Arc FurnaceQingxuan Luo (11825660) 20 December 2021 (has links)
<p>Electric arc furnace (EAF) is a
furnace that utilizes electric energy and chemical energy to melt scraps and
produce liquid steel. During the industrial process of EAF, an electric arc
will be generated around the electrode located at the center of the furnace,
and this phenomenon will generate a lot of heat. If any part of the electric
arc is exposed to the freeboard region, a region above the slag layer inside
the furnace, the heat emitted by this exposed arc can significantly heat on
side wall temperatures, resulting in an overheating issue of side wall. Water-cooling
panels (WCP) have been used to cool down the side wall, but the concentrated
overheating area, may damage the water-cooling panel. In this study, a
combination of slag foaming phenomenon and electric arc has been considered. A
calculator is developed based on several arc models to calculate the parameters
about slag foaming and arc power. The parameters can be used as input in a
computational fluid dynamics (CFD) model. The commercial software, ANSYS FLUENT<sup>®</sup>, was utilized to give a prediction
of the side wall temperature distribution of an EAF. Data from the plant has
been used to validate the calculation results. Furthermore, a series of
parametric studies has been investigated to study the influence of operating
conditions. The developed model can help to predict the risk of overheating from
given electrode conditions and slag compositions.</p>
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Vývoj modelu kalcinace pro ANSYS Fluent / Calcination model developement for ANSYS FluentAnderle, Milan January 2017 (has links)
The aim of the diploma thesis was creating a decarbonisation model of lime, implementation the model into CFD tool ANSYS Fluent and to test the decarbonisation model in a model of a real reactor. The required model was based on assumptions for a Shrinking Core Model (SCM). The main objective of this work was the non-catalytic conversion of substances and the search for the most used mathematical models for calcination. The CFD calculation, the sensitivity analysis and the Fluente parametric study were used. Data on the composition of gas flow, temperature, pressure and mass flow of limestone particles were selected for input variables. The particle model called Multiple Surface Reactions (MSR), which is a standard part of Fluent, was used at first. Subsequently, a UDF which was based on the SCM assumptions was written in the programming language C. The results of the CFD calculation were compared with the experimental values from the dissertation. It has been found that the MSR is sufficiently precise for calculation purposes but neglects the internal diffusion of CO2 through the CaO layer which forms behind the reaction front during calcination. It was found that it is possible to solve the flow with ongoing calcination without the need to know the parameters of the Arrhenian equation if the UDF is used. The created UDF incorporates the influence of intraparticular CO2 diffusion on the overall reaction rate.
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Reverzní vírová turbina / Reversible swirl turbinePalička, Miroslav January 2020 (has links)
This diploma thesis describes hydraulic design of Swirl turbine, dedicated to be used for tidal powerplant and study possibilities of the turbine to work in turbine, reverse turbine, pump and reverse pump regime. From individual regimes, graphical characteristics of created hydraulic design were created and compared, using CFD simulations.
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Droplet interface bilayers: microfluidic methods to model pharmacokinetics in artificial cell membranesStephenson, Elanna 20 September 2021 (has links)
Modern drug development is an astronomically expensive and time consuming undertaking. Because of this, studying the pharmacokinetic properties of drugs in vitro has become an integral step early in the process of drug development, with the goal of preventing costly failures late in the process, and dangerous side effects. Artificial phospholipid bilayers known as droplet interface bilayers (DIBs) have the potential to be used for these pharmacokinetics assays, combining the low cost of cell-free assays with the ability to more closely mimic structures found in life than current cell-free in vitro techniques. Combined with the reproducibility, ease of use, and low reagent consumption found with microfluidic methods, disruptive new low cost techniques for assessing pharmacokinetics in drug development may be possible using DIBs as an artificial cell membrane model.
In this work, I establish the potential of DIBs to be used as a pharmacokinetics modelling platform, and advance the use of microfluidic methods for carrying out pharmacokinetics assays in drug discovery. I first developed a new microfluidic platform for the formation of DIBs, which sought to solve some of the shortcomings of current microfluidic methods for DIB formation (Chapter 2). This device is the first that can be used to form DIB networks from dissimilar droplets in parallel, without use of active controls, and with droplet contact gentle enough to enable use of biomimetic lipid mixtures. I examine for the first time the behaviour of phospholipids on microfluidic devices, and characterise the interaction that they have with a common material used to construct microfluidic devices (Chapter 3). Not only has this interaction never been studied before, but my unexpected findings indicate a new area requiring further study in order to advance the adoption of DIBs on microfluidic devices. In collaboration with my colleague Jaime Korner, I use my newly developed microfluidic platform to carry out an on-chip permeation assay for the first time using biomimetic lipid formulations and bespoke compartments modelled after the human intestine. We demonstrate that this on-chip assay has predictive accuracy greater than that of a current widely used cell-free technique (Chapter 4). Finally, I demonstrate that a DIB based microfluidic platform enables, and is critical for, characterising the effect of structural features such as membrane asymmetry on drug permeation. With this, I find measurable, previously unknown effects of membrane asymmetry on the absorption of the chemotherapy drug doxorubicin, highlighting a possible contributing factor to chemoresistance in some cancers (Chapter 5). I find, and demonstrate throughout the body of this work that microfluidic methods and DIBs can not only provide alternatives to current cell-free in vitro pharmacokinetics assays, but that they can exceed the performance of existing assays, and be used for entirely new ways of examining pharmacokinetics. Through building bespoke artificial cell membranes from the ground up, I hope to demonstrate herein the great potential of these powerful new cell-free methods. / Graduate / 2022-09-12
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CFD Heat Transfer Simulation of the Human Upper Respiratory Tract for Oronasal Breathing ConditionSrinivasan, Raghavan January 2011 (has links)
In this thesis. a three dimensional heat transfer model of heated airflow through the upper human respiratory tract consisting of nasal, oral, trachea, and the first two generations of bronchi is developed using computational fluid dynamics simulation software. Various studies have been carried out in the literature investigating the heat and mass transfer characteristics in the upper human respiratory tract, and the study focuses on assessing the injury taking place in the upper human respiratory tract and identifying acute tissue damage based on level of exposure. The model considered is for the simultaneous oronasal breathing during the inspiration phase with high volumetric flow rate of 90/liters minute and a surrounding air temperature of 100 degrees centigrade. The study of the heat and mass transfer, aerosol deposition and flow characteristics in the upper human respiratory tract using computational fluid mechanics simulation requires access to a two dimensional or three dimensional model for the human respiratory tract. Depicting an exact model is a complex task since it involves the prolonged use of imaging devices on the human body. Hence a three dimensional geometric representation of the human upper respiratory tract is developed consisting of nasal cavity, oral cavity, nasopharynx, pharynx, oropharynx, trachea and first two generations of the bronchi. The respiratory tract is modeled circular in cross-section and varying diameter for various portions as identified in this study. The dimensions are referenced from the literature herein. Based on the dimensions, a simplified model representing the human upper respiratory tract is generated.This model will be useful in studying the flow characteristics and could assist in treatment of injuries to the human respiratory tract as well as help optimize drug delivery mechanism and dosages. Also a methodology is proposed to measure the characteristic dimension of the human nasal and oral cavity at the inlet/outlet points which are classified as internal measurements.
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Generation and Analysis of Streamwise Vortices from Vortex Tube ApparatusCarlson, Bailey McKay January 2020 (has links)
A pressurized vortex tube is used to generate streamwise vortices in a wind tunnel and the resulting flow behavior is analyzed. The apparatus is intended to verify computational data from the AFRL by offering a method of conducting real-world counterpart experiments. The apparatus design process and other considered approaches are discussed. The vortex tube is operated at pressures of 20, 30 and 40 psi while the wind tunnel is operated at 3, 5, 10 and 20% capacity. Flow measurements are performed using particle image velocimetry to observe vortices and freestream interactions from which velocity and vorticity data is comparatively analyzed. Results indicate that vortex velocity greater than freestream flow velocity is a primary factor in maintaining vortex structures further downstream, while increased supply pressure and reduced freestream velocity also reduce vortex dissipation rate. A brief analysis of the vortex interaction with a downstream airfoil is presented to support future work.
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Simulations to determine the drag coefficient of a floating photovoltaic systemForsgren, Fritz January 2021 (has links)
A floating photovoltaic (FPV) system is a structure of solar cells placed on water, where the solar cells are mounted on floating modules that have to be anchored. To know the size of the anchoring equipment, the forces on the FPV need to be determined. The main force affecting the FPV is the wind force. The force from the wind is directly correlated with the drag coefficient, hence we need to determine the drag coefficient to understand the system. The goal of this thesis is to first find the difference in the drag coefficient between two configurations of FPVs and for a second case with a floater added in front of both setups. To determine the difference in drag coefficient, between the two cases, the wind flow over the FPVs were studied by simulations using computational fluid dynamics (CFD) and calculating the drag coefficient for each case. The simulations showed that the difference in drag coefficient in the cases without a floater had the biggest difference between the first FPVs where the difference was a factor of two. For the cases with the floater, the simulations gave a similar result for the two configurations, leading to a smaller difference between the two configurations. We conclude that if a system without a floater is built, the configurations of the FPVs are important, while if the floater is added in front of the FPV there is less importance in the configurations of the FPVs.
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Novel Inverse Airfoil Design Utilizing Parametric EquationsLane, Kevin A 01 June 2010 (has links)
The engineering problem of airfoil design has been of great theoretical interest for almost a century and has led to hundreds of papers written and dozens of methods developed over the years. This interest stems from the practical implications of airfoil design. Airfoil selection significantly influences the application's aerodynamic performance. Tailoring an airfoil profile to its specific application can have great performance advantages. This includes considerations of the lift and drag characteristics, pitching moment, volume for fuel and structure, maximum lift coefficient, stall characteristics, as well as off-design performance.
A common way to think about airfoil design is optimization, the process of taking an airfoil and modifying it to improve its performance. The classic design goal is to minimize drag subject to required lift and thickness values to meet aerodynamic and structural constraints. This is typically an expensive operation depending on the selected optimization technique because several flow solutions are often required in order to obtain an updated airfoil profile. The optimizer requires gradients of the design space for a gradient-based optimizer, fitness values of the members of the population for a genetic algorithm, etc.
An alternative approach is to specify some desired performance and find the airfoil profile that achieves this performance. This is known as inverse airfoil design. Inverse design is more computationally efficient than direct optimization because changes in the geometry can be related to the required change in performance, thus requiring fewer flow solutions to obtain an updated profile. The desired performance for an inverse design method is specified as a pressure or velocity distribution over the airfoil at given flight conditions. The improved efficiency of inverse design comes at a cost. Designing a target pressure distribution is no trivial matter and has severe implications on the end performance. There is also no guarantee a specified pressure or velocity distribution can be achieved. However, if an obtainable pressure or velocity distribution can be created that reflects design goals and meets design constraints, inverse design becomes an attractive option over direct optimization.
Many of the available inverse design methods are only valid for incompressible flow. Of those that are valid for compressible flow, many require modifications to the method if shocks are present in the flow. The convergence of the methods are also greatly slowed by the presence of shocks. This paper discusses a series of novel inverse design methods that do not depend on the freestream Mach number. They can be applied to design cases with and without shocks while not requiring modifications to the methods. Shocks also do not have a significant impact on the convergence of the methods. Airfoils are represented with parametric equations from the CST method to control shape changes and relate them to the required changes in the pressure or velocity distribution. To display the power of the methods, design cases are presented in the subsonic and transonic regimes. A circulation control design case is also presented using one of the methods to further show the robustness of the method.
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A Computational Fluid Dynamics (CFD) Analysis of the Aerodynamic Effects of the Seams on a Two-Dimensional Representation of a Soccer BallRohr, Allen R 01 December 2018 (has links)
Most major sports today use a dedicated ball or projectile with specific shape, size, and surface geometry, except for soccer. Over the history of the sport, the surface geometry and design stayed relatively unchanged, sewn together using 32 pentagonal and hexagonal panels. However, recent innovations in panel designs differ substantially from the traditional 32 panel ball. The effects these new designs have on the aerodynamic characteristics of the ball have remained largely unknown, even with the influx of experimental research completed in the past decade. Experimental studies have been broad in scope, analyzing an entire ball in wind tunnels or full flow paths in trajectory analyses. Computational efforts have been too assumptive in flow conditions, such as a fully turbulent flow field, which has not yielded accurate representations of the flow phenomenon. This study investigates the aerodynamic effects of the seam on a two-dimensional representation of a non-rotating soccer ball using Computational Fluid Dynamics (CFD). By applying a transitional solver to the narrowed scope of a two-dimensional flow domain, with a single seam in cross-flow, the effects of the seam on the boundary layer and overall transient flow structure can be more accurately modeled. Data analysis suggests the seam produces a local effect on skin friction, however, that effect does not materialize into a premature boundary layer transition or delayed separation point, as predicted by literature. A detailed flow visualization is consistent with this result, displaying expected symmetric vortex shedding similar to a smooth cylinder, but not fully capturing the effects of the seam, reinforcing the need for expanding computational research efforts in this field.
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Numerické modelování proudění v bezpečnostních objektech malých vodních nádrží / Numerical Modelling of Flow over Spillway in Small DamsVaněk, Jakub January 2012 (has links)
The master´s thesis deals with the numerical modeling of flow in the emergency spillways of small dams. It is solved the flow rate capacity of a weir and of spillway called „duckbill-type“. Sharp crested weirs and long crested weirs are modeled using numerical simulations in ANSYS. Hydraulically complex spillway called „duckbill-type“ was modeled in the Flow-3D. The results of the discharge coefficients are compared with data in the hydraulic literature.
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