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Articles 391 - 420 of 448

Full-Text Articles in Engineering

Cfd Simulations For The Effect Of Unsteady Wakes On The Boundary Layer Of A Highly Loaded Low Pressure Turbine Airfoil (L1a), Samuel J. Vinci Jan 2011

Cfd Simulations For The Effect Of Unsteady Wakes On The Boundary Layer Of A Highly Loaded Low Pressure Turbine Airfoil (L1a), Samuel J. Vinci

ETD Archive

The study of a very high lift, low-pressure turbine airfoil in the presence of unsteady wakes was performed computationally and compared against experimental results. The experimental data were collected in a low speed wind tunnel under high (4.9 ) and then low (0.6 ) freestream turbulence intensity conditions on a linear cascade with wakes that were produced from moving rods upstream of the cascade. The flow coefficient was kept at 0.7 while the rod to blade spacing was changed from 1 to 1.6 to 2 blade spacings. These cases were conducted for Reynolds number equal to 25,000 and 50,000, based …

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An Implicit High-Order Spectral Difference Method For The Compressible Navier-Stokes Equations Using Adaptive Polynomial Refinement, Caleb J. Barnes Jan 2011

An Implicit High-Order Spectral Difference Method For The Compressible Navier-Stokes Equations Using Adaptive Polynomial Refinement, Caleb J. Barnes

Browse all Theses and Dissertations

A high/variable-order numerical simulation procedure for gas dynamics problems was developed to model steep grading physical phenomena. Higher order resolution was achieved using an orthogonal polynomial Gauss-Lobatto grid, adaptive polynomial refinement and artificial diffusion activated by a pressure switch. The method is designed to be computationally stable, accurate, and capable of resolving discontinuities and steep gradients without the use of one-sided reconstructions or reducing to low-order. Solutions to several benchmark gas-dynamics problems were produced including a shock-tube and a shock-entropy wave interaction. The scheme's 1st-order solution was validated in comparison to a 1st-order Roe scheme solution. Higher-order solutions were shown …

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Dual-Scale Modeling Of Two-Phase Fluid Transport In Fibrous Porous Media, Alireza Ashari Nov 2010

Dual-Scale Modeling Of Two-Phase Fluid Transport In Fibrous Porous Media, Alireza Ashari

Theses and Dissertations

The primary objective of this research is to develop a mathematical framework that could be used to model or predict the rate of fluid absorption and release in fibrous sheets made up of solid or porous fibers. In the first step, a two-scale two-phase modeling methodology is developed for studying fluid release from saturated/unsaturated thin fibrous media made up of solid fibers when brought in contact with a moving solid surface. Our macroscale model is based on the Richards’ equation for two-phase fluid transport in porous media. The required constitutive relationships, capillary pressure and relative permeability as functions of the …

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Design Of A Novel Hand-Held Pneumatic Vacuum Pad Using Cfd, Jyh-Chyang Renn, Chin-Yi Cheng, Yong-Chao Yang Oct 2010

Design Of A Novel Hand-Held Pneumatic Vacuum Pad Using Cfd, Jyh-Chyang Renn, Chin-Yi Cheng, Yong-Chao Yang

Journal of Marine Science and Technology–Taiwan

In this paper, a novel hand-held pneumatic vacuum pad is developed using CFD-simulation. CFD is the abbreviation of Computational Fluid Dynamics, which is a powerful and reliable tool to provide an effective insight into the flow field numerically. Nowadays, application of pneumatic vacuum pads may be found in many different real industries, especially in the field of automatic conveyer system, automatic or manual assembly line, semiconductor industry as well as wafer factory, etc. Traditional vacuum pads are generally mounted on robots or other machines to form automated manufacturing systems. In this paper, however, a novel cylindrical vacuum pad specially designed …

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Time-Averaged Modelling Of Cfbs – Analysis Of The Terms In The Momentum Equations, Sirpa Kallio, Maiju Seppälä, Veikko Taivassalo May 2010

Time-Averaged Modelling Of Cfbs – Analysis Of The Terms In The Momentum Equations, Sirpa Kallio, Maiju Seppälä, Veikko Taivassalo

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

The features of the terms in the time-averaged momentum equation for the solid phase are examined for three CFB units ranging from a laboratory-scale unit to a small CFB boiler. The CFD simulations were based on the Eulerian granular model of the Fluent software. The time-averaged terms calculated during the time dependent simulations are analysed and conclusions on their relative importance are drawn. An analysis of the terms in the vertical solids momentum equation in the central region of a CFB is presented.

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Cfd Simulation Of A Liquid-Fluidized Bed Of Binary Particles, Long Fan, John Grace, Norman Epstein May 2010

Cfd Simulation Of A Liquid-Fluidized Bed Of Binary Particles, Long Fan, John Grace, Norman Epstein

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

The ability of computational fluid dynamics to predict the expansion and segregation of a binary solids mixture in a liquid-solid fluidized bed is investigated. Unsteady laminar flow is simulated by a modified two-dimensional Eulerian-Eulerian model in Fluent 6.3. The predictions are compared with experimental results for binary particles in the same narrow (1.00-1.18 mm) size range, but with different densities, 1600 and 1900 kg/m3, fluidized by water (1). The voidages and heights of two layers which form, each dominated by one particle species, were found to be sensitive to small changes in particle properties (diameter, density, sphericity), as well as …

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Dem-Cfd Modelling Of A Fluidized Bed Spray Granulator, Lennart Fries, Sergiy Antonyuk, Stefan Heinrich, Stefan Palzer May 2010

Dem-Cfd Modelling Of A Fluidized Bed Spray Granulator, Lennart Fries, Sergiy Antonyuk, Stefan Heinrich, Stefan Palzer

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

Coupled DEM-CFD simulations have been performed to study the hydrodynamics of a Wurster granulator on the scale of individual particles. Based on extensive material tests, the collision behaviour of dry "Gamma"-Al2O3 particles is identified and incorporated into the model. The effect of process parameters like air flow rate and geometry details like the Wurster position is studied. Based on a physical description of the material properties, an effective tool for design and scale-up of a Wurster granulator is obtained.

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Design And Scale-Up Of Production Scale Stirred Tank Fermentors, Ryan Z. Davis May 2010

Design And Scale-Up Of Production Scale Stirred Tank Fermentors, Ryan Z. Davis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the bio/pharmaceutical industry, fermentation is extremely important in pharmaceutical development, and in microbial research. However, new fermentor designs are needed to improve production and reduce costs of complex systems such as cultivation of mammalian cells and genetically engineered micro-organisms. Traditionally, stirred tank design is driven by the oxygen transfer capability needed to achieve cell growth. However, design methodologies available for stirred tank fermentors are insufficient and many times contain errors. The aim of this research is to improve the design of production scale stirred tank fermentors through the development of dimensionless correlations and by providing information on aspects of …

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Assessing The V2-F Turbulence Models For Circulation Control Applications, Travis M. Storm Apr 2010

Assessing The V2-F Turbulence Models For Circulation Control Applications, Travis M. Storm

Master's Theses

In recent years, airports have experienced increasing airport congestion, partially due to the hub-and-spoke model on which airline operations are based. Current airline operations utilize large airports, focusing traffic to a small number of airports. One way to relieve such congestion is to transition to a more accessible and efficient point-to-point operation, which utilizes a large web of smaller airports. This expansion to regional airports propagates the need for next-generation low-noise aircraft with short take-off and landing capabilities. NASA has attacked this problem with a high-lift, low-noise concept dubbed the Cruise Efficient Short Take-Off and Landing (CESTOL) aircraft. The goal …

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High Order Finite Elements For Lagrangian Computational Fluid Dynamics, Truman Everett Ellis Apr 2010

High Order Finite Elements For Lagrangian Computational Fluid Dynamics, Truman Everett Ellis

Master's Theses

A general finite element method is presented to solve the Euler equations in a Lagrangian reference frame. This FEM framework allows for separate arbitrarily high order representation of kinematic and thermodynamic variables. An accompanying hydrodynamics code written in Matlab is presented as a test-bed to experiment with various basis function choices. A wide range of basis function pairs are postulated and a few choices are developed further, including the bi-quadratic Q2-Q1d and Q2-Q2d elements. These are compared with a corresponding pair of low order bi-linear elements, traditional Q1-Q0 and sub-zonal pressure Q1-Q1d. Several test problems are considered including static convergence …

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A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control, Olga V. Kartuzova Jan 2010

A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control, Olga V. Kartuzova

ETD Archive

Jets have been utilized in various turbomachinery applications in order to improve gas turbines performance. Jet pulsation is a promising technique because of the reduction in the amount of air removed from compressor, which helps to increase turbine efficiency. In this work two areas of pulsed jets applications were investigated, first one is film cooling of High Pressure Turbine (HPT) blades and second one is flow separation control over Low Pressure Turbine (LPT) airfoil using Vortex Generator Jets (VGJ) The inlet temperature to the HPT significantly affects the performance of the gas turbine. Film cooling is one of the most …

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Transitional Flow Prediction Of A Compressor Airfoil, Vivek Hariharan Jan 2010

Transitional Flow Prediction Of A Compressor Airfoil, Vivek Hariharan

University of Kentucky Master's Theses

The steady flow aerodynamics of a cascade of compressor airfoils is computed using a two-dimensional thin layer Navier-Stokes flow solver. The Dhawan and Narasimha transition model and Mayle‟s transition length model were implemented in this flow solver so that transition from laminar to turbulent flow could be included in the computations. A method to speed up the convergence of the fully turbulent calculations has been introduced. In addition, the effect of turbulence production formulations and including streamline curvature correction in the Spalart-Allmaras turbulence model on the transition calculations is studied. These transitional calculations are correlated with the low and high …

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Computational Study Of Fluid-Valve Interaction Involving Deep Vein Thrombosis, Upendra Parimi Jan 2010

Computational Study Of Fluid-Valve Interaction Involving Deep Vein Thrombosis, Upendra Parimi

Open Access Theses & Dissertations

The venous valves in veins carry on the important function of eliminating the retrograde (re-verse) flow of blood in veins and help the veins to carry on their work effectively. The abnormal functioning of venous valves can cause deep vein thrombosis (DVT) which is a phenomena caused by clotting in deep veins. The importance of the thesis work lies in understanding the role of blood flow dynamics in Deep Vein Thrombosis (DVT). Elderly People and pregnant women are the ones who are most likely to develop DVT. It was determined from previous studies that women in their postpartum period are …

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Development Of An Unsteady Aeroelastic Solver For The Analysis Of Modern Turbomachinery Designs, Timothy James Leger Jan 2010

Development Of An Unsteady Aeroelastic Solver For The Analysis Of Modern Turbomachinery Designs, Timothy James Leger

Browse all Theses and Dissertations

Developers of aircraft gas turbine engines continually strive for greater efficiency and higher thrust-to-weight ratio designs. To meet these goals, advanced designs generally feature thin, low aspect airfoils, which offer increased performance but are highly susceptible to flow-induced vibrations. As a result, High Cycle Fatigue (HCF) has become a universal problem throughout the gas turbine industry and unsteady aeroelastic computational models are needed to predict and prevent these problems in modern turbomachinery designs. This research presents the development of a 3D unsteady aeroelastic solver for turbomachinery applications. To accomplish this, a well established turbomachinery Computational Fluid Dynamics (CFD) code called …

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Designing Of Energy Efficient Indoor Environments Using A Localized Radial Basis Function Meshless Method, Victor Huayamave Jan 2010

Designing Of Energy Efficient Indoor Environments Using A Localized Radial Basis Function Meshless Method, Victor Huayamave

Electronic Theses and Dissertations

Around the world, the energy over consumption issue has been one of the key socio-economic and political challenges, which has drastically worsened over the last few years. Over the years engineers and environmentalists have proposed several approaches to improve energy efficiency. One is to reduce energy demand by improving consumption habits and a second approach is to introduce the use of a "greener" concept by using biomaterials in a diverse and more efficient manner in engineering construction to create energy efficient environments. This work will investigate the effects of using "green" stabilized earth materials to provide and enhance thermal regulation …

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Parallelization Of Performance Limiting Routines In The Computational Fluid Dynamics General Notation System Library, Kyle Horne Dec 2009

Parallelization Of Performance Limiting Routines In The Computational Fluid Dynamics General Notation System Library, Kyle Horne

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Computational Fluid Dynamics General Notation System provides a unified way in which computational fluid dynamics data can be stored, but does not support the parallel I/O capabilities now available from version five of the Hierarchical Data Format library which serves as a back end for he standard. To resolve this deficiency, a new parallel extension library has been written and benchmarked for this work which can write files compliant with the standard using parallel file access modes. When using this new library, the write performance shows an increase of four-fold in some cases when compared to the same hardware …

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2-D And 3-D Assessment Of Cambered And Symmetric Airfoils: A Cfd Study, Tuncay Kamas Dec 2009

2-D And 3-D Assessment Of Cambered And Symmetric Airfoils: A Cfd Study, Tuncay Kamas

All Theses

A two dimensional and three dimensional computational study has been carried out respectively regarding aerodynamic forces affecting a symmetric airfoil, NACA0015 and a cambered airfoil, NACA2414. The negative lift (down force) and drag forces were predicted through the simulation of airflows over inverted rear-wings in different configurations namely; varying incidences i.e. angles of attack of the airfoils, two dimensional cross section of the inverted rear wings to be mounted on back of a car, and varying speeds of initial airflow.
The downforce increases as the angle of attack increases however, if an inverted rear wing is fixed on a car …

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Age Effects On Iron-Based Pipes In Water Distribution Systems, Ryan T. Christensen Dec 2009

Age Effects On Iron-Based Pipes In Water Distribution Systems, Ryan T. Christensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pipes in water distribution systems may change as they age. The accumulation of corrosion byproducts and suspended particles on the inside wall of aged pipes can increase pipe roughness and reduce pipe diameter. To quantify the hydraulic effects of irregular accumulation on the pipe walls, eleven aged pipes ranging in diameter from 0.020-m (0.75-in) to 0.100-m (4-in) and with varying degrees of turberculation were located and subjected to laboratory testing. The laboratory test results were used to determine a relationship between pipe diameter reduction and Hazen-Williams C. This relationship, combined with a manipulation of the Hazen-Williams equation, provided a simple …

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3d Numerical Modeling Of Hydrodynamic Flow, Sediment Deposition And Transport In Stormwater Ponds And Alluvial Channels, Leying Zhang Jul 2009

3d Numerical Modeling Of Hydrodynamic Flow, Sediment Deposition And Transport In Stormwater Ponds And Alluvial Channels, Leying Zhang

Civil & Environmental Engineering Theses & Dissertations

Prediction of flow and sediment transport is an important and challenging problem for stormwater management and river engineering applications. This thesis concerns primarily the computation of flow, sediment deposition and transport processes in stormwater ponds and alluvial channels based on a multiphase flow approach in modeling sediment transport. Starting from an existing hydrodynamic Reynolds Averaged Navier-Stokes flow solver, numerical models are developed to predict flow, sediment deposition and transport under the FLUENT software package. Two types of sediment transport models are formulated to consider quantities of present sediment phase volume fractions: a Discrete Phase Model in a Lagrangian frame where …

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Demonstration Of A Completely Described Swirling Jet Experiment Used For Numerical Validation, Brandon M. Wilson May 2009

Demonstration Of A Completely Described Swirling Jet Experiment Used For Numerical Validation, Brandon M. Wilson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis demonstrates the standard for the design of an experimental model to be used for numerical validation purposes. It is proposed that numerical models may be assessed more accurately and directly by validation with a completely described experimental model, consisting of accurate descriptions of the operating conditions, fluid properties, and experimental uncertainties. This idea is demonstrated using an experimental model of a swirling jet at three Reynolds numbers (Re = 550, 2560, and 3650), with vortex breakdown existing in the higher two Reynolds number cases. Measurements of the swirling jet were obtained at two locations upstream of the jet …

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Hydrodynamic Forces On Inundated Bridge Decks, Kornel Kerenyi, Tanju Sofu, Junke Guo Jan 2009

Hydrodynamic Forces On Inundated Bridge Decks, Kornel Kerenyi, Tanju Sofu, Junke Guo

United States Department of Transportation: Publications

The hydrodynamic forces experienced by an inundated bridge deck have great importance in the design of bridges. Specifically, the drag force, lift force, and the moment acting on the bridge deck under various levels of inundation and a range of flow conditions influence the design and construction of the bridge. This report explores the forces acting on bridges in two ways. First, through physical experimentation on scaled-down bridge deck models tested in a flume and then with computational fluid dynamics (CFD) simulation models. Three bridge deck prototypes were used for the experimentation: a typical six-girder highway bridge deck, a three-girder …

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Employing The Spectral Collocation Method In The Modeling Of Laminar Tube Flow Dynamics, Corey Michael Thibeault Jan 2009

Employing The Spectral Collocation Method In The Modeling Of Laminar Tube Flow Dynamics, Corey Michael Thibeault

All Graduate Theses, Dissertations, and Other Capstone Projects

The spectral collocation method is a numerical approximation technique that seeks the solution of a differential equation using a finite series of infinitely differentiable basis functions. This inherently global technique enjoys an exponential rate of convergence and has proven to be extremely effective in computational fluid dynamics. This paper presents a basic review of the spectral collocation method. The derivation is driven with an example of the approximation to the solution of a 1D Helmholtz equation. A Matlab code modeling two fluid dynamics problems is then given. First, the classic two-dimensional Graetz problem is simulated and compared to an analytical …

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Experimental And Numerical Study Of A Proton Exchange Membrane Electrolyzer For Hydrogen Production, Sachin S. Deshmukh Jan 2009

Experimental And Numerical Study Of A Proton Exchange Membrane Electrolyzer For Hydrogen Production, Sachin S. Deshmukh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen as a fuel source has received attention from researchers globally due to its potential to replace fossil based fuels for energy production. Research is being performed on hydrogen production, storage and utilization methods to make its use economically feasible relative to current energy sources. The PEM electrolyzer is used to produce hydrogen and oxygen using water and electricity. Focus of our study is to provide a benchmark experiment and numerical model of a single cell electrolyzer that can assist in improving the current state of understanding of this system. Parametric analysis of an experimental cell was performed to understand …

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Cfd As Applied To The Design Of Short Takeoff And Landing Vehicles Using Circulation Control, Tyler M. Ball Jun 2008

Cfd As Applied To The Design Of Short Takeoff And Landing Vehicles Using Circulation Control, Tyler M. Ball

Master's Theses

The ability to predict the distance required for an aircraft to takeoff is an essential component of aircraft design. It involves aspects related to each of the major aircraft systems: aerodynamics, propulsion, configuration, structures, and stability and control. For an aircraft designed for short takeoffs and landings (STOL), designing the aircraft to provide a short takeoff distance, or more precisely the balanced field length (BFL), often leads to the use of a powered lift technique such as circulation control (CC). Although CC has been around for many years, it has never been used on a production aircraft. This is in …

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Development Of Automatic Cfd Grid Generation For The Design Of The Preliminary Wing Sweep Schedule For The Gulfstream Quiet Supersonic Jet, Ali Kazeneh May 2008

Development Of Automatic Cfd Grid Generation For The Design Of The Preliminary Wing Sweep Schedule For The Gulfstream Quiet Supersonic Jet, Ali Kazeneh

Master's Theses - Daytona Beach

The wing sweep schedule for the Gulfstream Quiet Supersonic Jet (wing and body) was investigated using CFD analysis methods. The use of automating the gridding procedure allowed for numerous cases to be investigated. The examination of the drag polar for different Mach cases indicated the optimum corresponding wing sweep position. The study results revealed that for the Mach 0.85 case, the wings should remain at the forward most pivoted position (Ʌ=25°). The Mach 1.1 case indicted that the wings should be in the fully swept back position (Ʌ=60°). The majority of the wing sweep transition occurs from Mach 0.85 to …

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Measurements And Modeling Of Coal Ash Deposition In An Entrained-Flow Reactor, Ryan P. Blanchard Apr 2008

Measurements And Modeling Of Coal Ash Deposition In An Entrained-Flow Reactor, Ryan P. Blanchard

Theses and Dissertations

Coal plays a significant role in meeting the world's need for energy and will continue to do so for many years to come. Economic, environmental, and public opinion are requiring coal derived energy to be cleaner and operate in a more narrow window of operating conditions. Fouling and slagging of heat transfer surfaces continues to be a challenge for maintaining boiler availability and expanding the use of available fuels and operating conditions. The work incorporates existing information in the literature on ash deposition into a User-Defined Function (UDF) for a commercial comprehensive combustion and CFD code. Results from the new …

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Parametric Optimization Design System For A Fluid Domain Assembly, Matthew Jackson Fisher Apr 2008

Parametric Optimization Design System For A Fluid Domain Assembly, Matthew Jackson Fisher

Theses and Dissertations

Automated solid modeling, integrated with computational fluid dynamics (CFD) and optimization of a 3D jet turbine engine has never been accomplished. This is due mainly to the computational power required, and the lack of associative parametric modeling tools and techniques necessary to adjust and optimize the design. As an example, the fluid domain of a simple household fan with three blades may contain 500,000 elements per blade passage. Therefore, a complete turbine engine that includes many stages, with sets of thirty or more blades each, will have hundreds of millions of elements. The fluid domains associated with each blade creates …

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Numerical Analysis Of Respiratory Aerosol Deposition: Effects Of Exhalation, Airway Constriction And Electrostatic Charge, Samir C. Vinchurkar Jan 2008

Numerical Analysis Of Respiratory Aerosol Deposition: Effects Of Exhalation, Airway Constriction And Electrostatic Charge, Samir C. Vinchurkar

Theses and Dissertations

The dynamics of particle laden flows are integral to the analysis of toxic particle deposition and medical respiratory aerosol delivery. Computational fluid-particle dynamics (CFPD) can play a critical role in developing a better understanding of particle laden flows, especially in a number of under-explored areas. The applications considered in this study include both the numerical aspects and the physical phenomena of respiratory aerosol transport. Objective I: Considering the effects of mesh type and grid convergence, four commonly implemented mesh styles were applied to a double bifurcation respiratory geometry and tested for flow patterns and aerosol deposition. Results indicated that the …

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An Investigation Into Fuel Cells And Flow Cytometers Optimal Design, Etim Sunday Udoetok Jan 2008

An Investigation Into Fuel Cells And Flow Cytometers Optimal Design, Etim Sunday Udoetok

LSU Doctoral Dissertations

The aim of the fuel cells part of this project was to investigate the performance of Proton Exchange Membrane Fuel Cells and closely related fuel cell types like the Alkaline Fuel Cells and Phosphoric Acid Fuel Cells. The investigation involved understanding the performance of fuel cells, addressing the shortcomings of currently used designs, and finding new methods for improving the performance of fuel cells. CFD was used to study flow channels and information learned from the study was used to design a new and improved flow channel. A prototype of the new design was fabricated, tested and found to perform …

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Understanding The Hydrodynamics In A 2-Dimensional Downer By Cfd-Dem Simulation, Yongzhi Zhao, Yi Cheng, Yulong Ding, Yong Jin May 2007

Understanding The Hydrodynamics In A 2-Dimensional Downer By Cfd-Dem Simulation, Yongzhi Zhao, Yi Cheng, Yulong Ding, Yong Jin

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The gas-solid flows in a 2-dimensional downer were simulated using a CFD-DEM method. The predicted macro-scale flow structure had good agreement with the experiments. The distinct clustering phenomena at meso-scale were revealed throughout the downer. Influences of the collision properties of the wall and the particles on the hydrodynamics in downer were investigated.

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