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Full-Text Articles in Engineering
Study Of Vortices Formation In Lateral Intakes Of Pumping Stations, Muhammad Elgindi
Study Of Vortices Formation In Lateral Intakes Of Pumping Stations, Muhammad Elgindi
Theses and Dissertations
The inefficient design of pumping stations leads to undesirable flow characteristics and the formation of vortices in the sump. These undesirable flow features adversely affect the pumping unit performance and increase the operation and maintenance cost. The aim of this thesis is to assess the ability of the Realizable turbulence model to predict the formation of free-surface and submerged vortices within lateral pumping stations’ intakes. Additionally, the study aims to investigate the effect of the flow ratio and bottom clearance on the flow characteristics and the vortices formation in the sump. Finally, the study introduces an assessment of curtain walls …
Reformulated Vortex Particle Method And Meshless Large Eddy Simulation Of Multirotor Aircraft, Eduardo J. Alvarez
Reformulated Vortex Particle Method And Meshless Large Eddy Simulation Of Multirotor Aircraft, Eduardo J. Alvarez
Theses and Dissertations
The vortex particle method (VPM) is a mesh-free approach to computational fluid dynamics (CFD) solving the Navier-Stokes equations in their velocity-vorticity form. The VPM uses a Lagrangian scheme, which not only avoids the hurdles of mesh generation, but it also conserves vortical structures over long distances with minimal numerical dissipation while being orders of magnitude faster than conventional mesh-based CFD. However, VPM is known to be numerically unstable when vortical structures break down close to the turbulent regime. In this study, we reformulate the VPM as a large eddy simulation (LES) in a scheme that is numerically stable, without increasing …
Surrogate Modeling Of Computational Aerodynamic Responses For A Generic Hypersonic Vehicle, Jacob R. Johanik
Surrogate Modeling Of Computational Aerodynamic Responses For A Generic Hypersonic Vehicle, Jacob R. Johanik
Theses and Dissertations
In the field of multidisciplinary hypersonic vehicle design, striking the balance between the accuracy and efficiency of a predictive aerodynamic response model is a significant challenge. In response to this challenge, the objective of this thesis is to evaluate the aerodynamic performance of a Generic Hypersonic Vehicle (GHV) using the technique of surrogate modeling Computational Fluid Dynamic data points across a large range of flight conditions. To accomplish this, the full CFD process was conducted by preparing the vehicle geometry, generating a grid, computing the flow, and post-processing the data. A three-dimensional, quasi-random distribution of 1000 points defined the design …
Cedar: A Dimensionally Adaptive Flow Solver For Cylindrical Combustors, Ty R. Hosler
Cedar: A Dimensionally Adaptive Flow Solver For Cylindrical Combustors, Ty R. Hosler
Theses and Dissertations
This thesis discusses the application, evaluation, and extension of dimensionally adaptive meshing to the numerical solution of velocity and pressure fields inside cylindrical reactors. Due to the high length to diameter ratios of many cylindrical reactor vessels the flow field can become axisymmetric, allowing for simplification of the governing equations and significant reduction in computational time required for solution. A fully 3D solver is developed from existing computational tools at BYU and validated against theoretical velocity profiles for pipe flow at various Reynolds numbers, as well as with experimental data for an axial-fired center jet with recirculating flow. Dimensionally adaptive …
Effect Of Ported Shroud Casing Treatment Modifications On Operational Range And Limits In A Centrifugal Compressor, Alexander A. Newell
Effect Of Ported Shroud Casing Treatment Modifications On Operational Range And Limits In A Centrifugal Compressor, Alexander A. Newell
Theses and Dissertations
The implementation of a ported shroud casing treatment is often used to extend the operating range of a centrifugal compressor. This work utilizes the STAR-CCM+ CFD package to analyze steady-state, single-passage simulations of a centrifugal compressor with and without a ported shroud to better understand how a ported shroud affects compressor flow physics. Verification and validation of simulations were conducted by comparison of results with a time-accurate full-annulus simulation and experimental data. Four different ported shroud revisions were considered and modeled along the full range of their stable operation, with emphasis placed on the flow limits of choke and stall. …
Co-Milling And Cofiring Of Woody Biomass With Coal In Utility Boilers: Enabling Technology Through Experiments And Modelling, Seyedhassan Fakourian
Co-Milling And Cofiring Of Woody Biomass With Coal In Utility Boilers: Enabling Technology Through Experiments And Modelling, Seyedhassan Fakourian
Theses and Dissertations
Beetle-killed trees and woody residues degenerate and may lead to wildfires and uncontrolled CO2 emission. Woody biomass is known as a neutral CO2 solid fuel since it generates the same amount of CO2 that takes from atmosphere during its growing up. Cofiring woody biomass with coal in existing coal power plants is a reasonable solution to reduce the net amount of CO2 emission and decrease the risk of wildfires. However, there are some challenges ranging from providing and handling the woody biomass to the operation of cofiring woody biomass with coal. Co-milling of the fuels and ash deposition on the …
Computational Investigation Of The Effects Of Rotor-On-Rotor Interactions On Thrust And Noise, Austin R. Schenk
Computational Investigation Of The Effects Of Rotor-On-Rotor Interactions On Thrust And Noise, Austin R. Schenk
Theses and Dissertations
Recent advancements in electric propulsion systems have made electric vertical takeoff and landing aircraft a reality, and one that is seen as a partial solution to the growing issue of urban traffic congestion. Designing an aircraft with multiple smaller motors and rotors spread across the wings–referred to as distributed electric propulsion (DEP)–has shown great potential in help- ing improve electric aircraft performance by offering increased propulsive efficiency, augmented lift, and structural load distribution. For these reasons, DEP is one configuration that is currently being implemented into multiple prototype designs (e.g. NASA’s Maxwell X-57, Airbus Vahana, Opener BlackFly, and Joby S2). …
Investigating Inducer Performance Over A Wide Range Of Operating Conditions, David Tate Fanning
Investigating Inducer Performance Over A Wide Range Of Operating Conditions, David Tate Fanning
Theses and Dissertations
Inducer performance is investigated for a variety of inducer geometries operating at multiple flow conditions using computational fluid dynamics. Inducers are used as a first stage in turbopumps to minimize cavitation and allow the pump to operate at lower inlet head conditions. The formation of inlet flow recirculation or backflow in the inducer occurs at low flow conditions and can lead to instabilities and cavitation-induced head breakdown. Backflow formation is often attributed to tip leakage flow. The performance of an inducer with and without tip clearance is examined. Removing the tip clearance eliminates tip leakage flow; however, backflow is still …
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Theses and Dissertations
Cavitation is a phenomenon that occurs in various turbomachinery applications causing drawbacks on the. Some of these downsides are damaging the components of the system, generating noise and vibration, and loss of the turbine efficiency over time. Thus, it is imperative to address issue of cavitation to increase the life span of the equipment in addition to improve the system performance. This thesis introduces a method used to mitigate the cavitation phenomenon in a 3-inch Kaplan hydro turbine via injecting air at the leading edge of the rotor blades. The study is based on modeling the turbine using Computational Fluid …
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Theses and Dissertations
Cavitation is a phenomenon that occurs in various turbomachinery applications causing drawbacks on the. Some of these downsides are damaging the components of the system, generating noise and vibration, and loss of the turbine efficiency over time. Thus, it is imperative to address issue of cavitation to increase the life span of the equipment in addition to improve the system performance. This thesis introduces a method used to mitigate the cavitation phenomenon in a 3-inch Kaplan hydro turbine via injecting air at the leading edge of the rotor blades. The study is based on modeling the turbine using Computational Fluid …
Thermal Gradient Characterization And Control In Micro-Fabricated Gas Chromatography Systems, Austin Richard Foster
Thermal Gradient Characterization And Control In Micro-Fabricated Gas Chromatography Systems, Austin Richard Foster
Theses and Dissertations
In order to make gas chromatography (GC) more widely accessible, considerable effort has been made in developing miniaturized GC systems. Thermal gradient gas chromatograpy (TGGC), one of the heating methods used in GC, has recieved attention over the years due to it's ability to enhance analyte focusing. The present work seeks to develop high performance miniaturized GC systems by combining miniaturized GC technology with thermal gradient control methods, creating miniaturized thermal gradient gas chromatography (µTGGC) systems. To aid in this development a thermal control system was developed and shown to successfully control various µTGGC systems. DAQ functionality was also included …
Analysis Of The Effects Of Inlet Distortion On Stall Cell Formation In A Transonic Compressor Using Create-Av Kestrel, Mikkel Andreas Unrau
Analysis Of The Effects Of Inlet Distortion On Stall Cell Formation In A Transonic Compressor Using Create-Av Kestrel, Mikkel Andreas Unrau
Theses and Dissertations
Accurately predicting fan performance, including bounds of operation, is an important function of any Computational Fluid Dynamics (CFD) package. The presented research uses a CFD code developed as part of the Computational Research and Engineering Acquisition Tools and Environment (CREATE), known as Kestrel, to evaluate a single stage compressor at various operating conditions. Steady-state, single-passage simulations are carried out to validate capabilities recently added to Kestrel. The analysis includes generating speedlines of total pressure ratio and efficiency, as well as radial total temperature and total pressure profiles at two axial locations in the compressor at various operating conditions and fan …
Wall Shear Stress In Simplified And Scanned Avian Respiratory Airways, Michael Sterling Farnsworth
Wall Shear Stress In Simplified And Scanned Avian Respiratory Airways, Michael Sterling Farnsworth
Theses and Dissertations
Birds uniquely produce sound through a vocal organ known as a syrinx. The presence of wall shear stress acting on the airway cells of any organism will affect how airway cells develop and multiply. Unique features of avian airway geometry and breathing pattern might have contributed to the development of the syrinx. This thesis examines wall shear stress in the trachea and first bronchi of avian geometries using computational fluid dynamics. The computational fluid dynamic simulations underwent grid- and time-independence studies and were validated using particle image velocimetry. Parameters such as bird size, bronchial branching angle, and breathing waveform were …
A Study Of Development Of A Micro Hydro Turbine System With A Rim Drive And Air Injection Treatment For Cavitation., Tomoki Sakamoto
A Study Of Development Of A Micro Hydro Turbine System With A Rim Drive And Air Injection Treatment For Cavitation., Tomoki Sakamoto
Theses and Dissertations
This thesis presents the study of Kaplan hydro turbines system at a very low head and air injection treatment to reduce cavitation happening around a turbine. Regarding the study of Kaplan hydroturbine system, optimization of hydro turbine system with a rim generator to gain a better performance was conducted by CFD and experiment. E-Motors, the partner of this research, is developing an integrated design to simplify manufacturing and installation. The integrated design includes a rim in the outside of the turbine runner to house the electrical generator rotor, namely rim drive. This approach enables a compact and simple assembly without …
Sensitivity Analysis Of Geometry Changes In The Simulation Of Basilar Aneurysms, Paul Eserkaln
Sensitivity Analysis Of Geometry Changes In The Simulation Of Basilar Aneurysms, Paul Eserkaln
Theses and Dissertations
Computer simulation is a useful tool in the research and treatment of basilar aneurysms. Current technology allows researchers to create 3D models from cerebral vasculature in-vivo, allowing for the investigation of surgical options with minimal risk to the patient. The method used to construct these models overlooks smaller lateral arterial branches which are difficult to discern due to resolution limits of the imaging process. These lateral branches have minimal impact on the overall blood flow through the basilar artery, but they play a significant role in the health of the patient, so it is important to ensure sufficient blood will …
Implementations Of Fourier Methods In Cfd To Analyze Distortion Transfer And Generation Through A Transonic Fan, Marshall Warren Peterson
Implementations Of Fourier Methods In Cfd To Analyze Distortion Transfer And Generation Through A Transonic Fan, Marshall Warren Peterson
Theses and Dissertations
Inlet flow distortion is a non-uniform total pressure, total temperature, or swirl (flow angularity) condition at an aircraft engine inlet. Inlet distortion is a critical consideration in modern fan and compressor design. This is especially true as the industry continues to increase the efficiency and operating range of air breathing gas turbine engines. The focus of this paper is to evaluate the Computational Fluid Dynamics (CFD) Harmonic Balance (HB) solver in STAR-CCM+ as a reduced order method for capturing inlet distortion as well as the associated distortion transfer and generation. New methods for quantitatively describing and analyzing distortion transfer and …
Numerical And Experimental Study Of Liquid Breakup Process In Solid Rocket Motor Nozzle, Yi-Hsin Yen
Numerical And Experimental Study Of Liquid Breakup Process In Solid Rocket Motor Nozzle, Yi-Hsin Yen
Theses and Dissertations
Rocket propulsion is an important travel method for space exploration and national defense, rockets needs to be able to withstand wide range of operation environment and also stable and precise enough to carry sophisticated payload into orbit, those engineering requirement makes rocket becomes one of the state of the art industry. The rocket family have been classified into two major group of liquid and solid rocket based on the fuel phase of liquid or solid state. The solid rocket has the advantages of simple working mechanism, less maintenance and preparing procedure and higher storage safety, those characters of solid rocket …
Concurrent Engineering Through Parallelization Of The Design-Analysis Process, Eric Joseph Wardell
Concurrent Engineering Through Parallelization Of The Design-Analysis Process, Eric Joseph Wardell
Theses and Dissertations
The disconnect between the way CAD and analysis applications handle model geometry has long been a hindrance to engineering design. Current industry practices often utilize outdated forms of geometry transfer between these different engineering software applications such as neutral file formats and direct translations. Not only to these current practices slow the engineering design process but they also hinder the integration of design and analysis programs.This thesis proposes a new, multi-user, integrated design-analysis architecture which allows auxiliary functions such as analysis and computer-aided manufacturing to be better connected with the computer-aided design. It is hypothesized that this new architecture will …
An Investigation Of Off-Design Operation In High Suction Performance Inducers, Ryan Collins Cluff
An Investigation Of Off-Design Operation In High Suction Performance Inducers, Ryan Collins Cluff
Theses and Dissertations
Three-dimensional two-phase unsteady CFD simulations were run on three and four-blade inducers for the purpose of analyzing differences in cavitation stability at design and off-design flow rates. At design flow rates, there were very small differences between the breakdown curves for the three and four-bladed inducers. However, at lower cavitation numbers, the three-bladed inducer exhibited up to three times the rotor forces than the four-bladed inducer. When moving to off-design flow rates, both inducers experienced multiple modes of cavitation instabilities including rotating cavitation, alternate-blade cavitation, and cavitation surge. The four-bladed inducer began experiencing the formation of these modes of instability …
A Study Of The Development Of An Analytical Wall Function For Large Eddy Simulation Of Turbulent Channel And Rectangular Duct Flow, Takahiko Hasegawa
A Study Of The Development Of An Analytical Wall Function For Large Eddy Simulation Of Turbulent Channel And Rectangular Duct Flow, Takahiko Hasegawa
Theses and Dissertations
This paper reports computational work of three-dimensional channel turbulent flow and rectangular duct flow with the Analytical Wall Function (AWF). The main purpose of this study is to establish and validate the new modeling of AWF for Large Eddy Simulation (LES-AWF). In order to compare the performance of the new modeling of LES-AWF, the conventional LES-AWF and Wall-resolved LES are applied. The new LES-AWF showed improvements of flow prediction in both of three-dimensional channel flow and rectangular duct flow, although the improvement in rectangular duct is relatively minor.
High Fidelity Time Accurate Cfd Analysis Of A Multi-Stage Turbofan At Various Operating Points In Distorted Inflow, David Bruce Weston
High Fidelity Time Accurate Cfd Analysis Of A Multi-Stage Turbofan At Various Operating Points In Distorted Inflow, David Bruce Weston
Theses and Dissertations
Inlet distortion is an important consideration in fan performance. Distortion can be caused through flight conditions and airframe-engine interfaces. The focus of this paper is a series of high-fidelity time accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan. These investigate distortion transfer and generation as well as the underlying flow physics of these phenomena under different operating conditions. The simulations are performed on the full annulus of a 3 stage fan. The code used to carry out these simulations is a modified version of OVERFLOW 2.2 developed as part of the Computational Research and Engineering Acquisition Tools and …
Validation Of A Modified Version Of Overflow 2.2 For Use With Turbomachinery Under Clean And Total Pressure Distorted Conditions And A Study Of Blade Loading In Distortion, Matthew L. Marshall
Validation Of A Modified Version Of Overflow 2.2 For Use With Turbomachinery Under Clean And Total Pressure Distorted Conditions And A Study Of Blade Loading In Distortion, Matthew L. Marshall
Theses and Dissertations
Inlet distortion is an important consideration in fan performance. Distortion can be generated through flight conditions and airframe-engine interfaces. The focus of this paper is a series of high-fidelity, time-accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan, investigating distortion transfer, distortion generation, and the underlying flow physics under different operating conditions. The simulations are full annulus and include 3 stages and the inlet guide vane (IGV). The code used to carry out these simulations is a modified version of Overflow2.2 that was developed as part of the Computational Research and Engineering Acquisition Tools and Environment (CREATE) program. The …
Cfd Assessment Of Respiratory Drug Delivery Efficiency In Adults And Improvements Using Controlled Condensational Growth, Ross L. Walenga
Cfd Assessment Of Respiratory Drug Delivery Efficiency In Adults And Improvements Using Controlled Condensational Growth, Ross L. Walenga
Theses and Dissertations
Pharmaceutical aerosols provide a number of advantages for treating respiratory diseases that include targeting high doses directly to the lungs and reducing exposure of other organs to the medication, which improve effectiveness and minimize side effects. However, difficulties associated with aerosolized drug delivery to the lungs include drug losses in delivery devices and in the extrathoracic region of human upper airways. Intersubject variability of extrathoracic and thoracic drug deposition is a key issue as well and should be minimized. Improvements to respiratory drug delivery efficiency have been recently proposed by Dr. P. Worth Longest and Dr. Michael Hindle through the …
High Fidelity Chemistry And Radiation Modeling For Oxy-Combustion Scenarios, Hassan A. Abdul Sater
High Fidelity Chemistry And Radiation Modeling For Oxy-Combustion Scenarios, Hassan A. Abdul Sater
Theses and Dissertations
To account for the thermal and chemical effects associated with the high CO2 concentrations in an oxy-combustion atmosphere, several refined gas-phase chemistry and radiative property models have been formulated for laminar to highly turbulent systems. This thesis examines the accuracies of several chemistry and radiative property models employed in computational fluid dynamic (CFD) simulations of laminar to transitional oxy-methane diffusion flames by comparing their predictions against experimental data. Literature review about chemistry and radiation modeling in oxy-combustion atmospheres considered turbulent systems where the predictions are impacted by the interplay and accuracies of the turbulence, radiation and chemistry models. Thus, …
Experimental And Computational Assessment Of Mechanical Circulatory Assistance Of A Patient-Specific Fontan Vessel Configuration, Steven Chopski
Experimental And Computational Assessment Of Mechanical Circulatory Assistance Of A Patient-Specific Fontan Vessel Configuration, Steven Chopski
Theses and Dissertations
The treatment of single ventricle anomalies is a formidable challenge for clinical teams caring for patients with congenital heart disease. Those patients fortunate to survive surgical palliation contend with lifelong physical limitations and late stage pathophysiology. A mechanical blood pump specifically designed to increase pressure in the great veins would augment flow through the lungs and provide hemodynamic stability until a donor heart is located. To support the development of such medical devices, this research characterized the fluid dynamics of mechanical assistance in the Fontan circulation by performing numerical analyses and particle image velocimetry (PIV) studies in a patient-specific in …
Methods For Identifying Acoustic Emissions From The Front Face Of A Small Piezoelectric Blower, Brad K. Solomon
Methods For Identifying Acoustic Emissions From The Front Face Of A Small Piezoelectric Blower, Brad K. Solomon
Theses and Dissertations
This thesis focuses on identifying acoustic noise generating components in piezoelectric blowers through transverse velocity measurements and the development of a numerical fluid model. Piezoelectric ceramics have proven useful for many industries and areas of research involving: high precision actuators, noise control, ultrasonic devices, and many other areas. As of late, a unique adaptation of piezoelectric ceramics is surfacing in the area of pumping and cooling. Air pumps that use these ceramics replace the traditional electric motor, resulting in lower power consumption, less moving parts, constant pressure gradients, lower overall weight, and a low profile. The current drawback of this …
Aerodynamic Analysis And Drag Coefficient Evaluation Of Time-Trial Bicycle Riders, Peter Nicholas Doval
Aerodynamic Analysis And Drag Coefficient Evaluation Of Time-Trial Bicycle Riders, Peter Nicholas Doval
Theses and Dissertations
Evaluation of drag coefficient often requires wind tunnel experiments and can be prohibitively expensive if not impossible for large objects or systems. Computational Fluid Dynamics (CFD) aerodynamic analysis offers an alternative approach and can be used as a very effective design tool in many industries: automotive, aerospace, marine, etc. The main objective of this research is to investigate feasibility of using non-contact digitizers for developing finite element models of large objects for subsequent CFD analysis. The developed methodology is applied to investigation of time-trial bicycle rider efficiency. Companies competing in this class of racing spend millions trying to optimize bicycle …
Investigation Of Heat Transfer And Flow Using Ribs Within Gas Turbine Blade Cooling Passage: Experimental And Hybrid Les/Rans Modeling, Sourabh Kumar
Investigation Of Heat Transfer And Flow Using Ribs Within Gas Turbine Blade Cooling Passage: Experimental And Hybrid Les/Rans Modeling, Sourabh Kumar
Theses and Dissertations
Gas turbines are extensively used for aircraft propulsion, land based power generation and various industrial applications. Developments in innovative gas turbine cooling technology enhance the efficiency and power output, with an increase in turbine rotor inlet temperatures. These advancements of turbine cooling have allowed engine design to exceed normal material temperature limits. For internal cooling design, techniques for heat extraction from the surfaces exposed to hot stream are based on the increase of heat transfer areas and on promotion of turbulence of the cooling flow. In this study, it is obtained by casting repeated continuous V and broken V shaped …
The Extraction Of Shock Waves And Separation And Attachment Lines From Computational Fluid Dynamics Simulations Using Subjective Logic, Matthew C. Lively
The Extraction Of Shock Waves And Separation And Attachment Lines From Computational Fluid Dynamics Simulations Using Subjective Logic, Matthew C. Lively
Theses and Dissertations
The advancement of computational fluid dynamics to simulate highly complex fluid flow situations have allowed for simulations that require weeks of computation using expensive high performance clusters. These simulations often generate terabytes of data and hinder the design process by greatly increasing the post-processing time. This research discusses a method to extract shock waves and separation and attachment lines as the simulation is calculating and as a post-processing step. Software agents governed by subjective logic were used to make decisions about extracted features in converging and converged data sets. Two different extraction algorithms were incorporated for shock waves and separation …
The Effects Of Micro- And Macro-Scale Geometric Parameters On Performance Of The Pleated Aerosol Filters, Shahryar Fotovati
The Effects Of Micro- And Macro-Scale Geometric Parameters On Performance Of The Pleated Aerosol Filters, Shahryar Fotovati
Theses and Dissertations
While most filters are made of pleated fibrous media, almost all existing theories of aerosol filtration are developed for flat media placed perpendicular to the air flow. Expressions developed for flat sheet media do not provide accurate information directly useful for designing a pleated filter, and therefore, most progress made in developing pleated filters is based on empiricism. This study is aimed at establishing an enabling knowledge that allows for a better design and optimization of pleated aerosol filters. This study is focused on developing a predictive simulation method that accounts for the influence of a filter’s micro-scale geometric parameters, …