Engineering Commons^™

Effect Of Swirl Ratio On Simulated Vortech Chamber Vortex Parameters, Samuel Kolar

Civil Engineering Undergraduate Honors Theses

A numerical simulator can use computational fluid dynamics (CFD) to model an experimental tornado-simulating chamber at Texas Tech University (known as VorTECH). Previous studies evaluating this particular CFD model have produced results that compare the touchdown swirl ratio (S_TD), core radius (r_c), maximum tangential velocity at touchdown (V_tmax @ S_TD), and height of the maximum tangential velocity (z_c) reasonably well with experimental data from the VorTECH facility. The effects of swirl ratio beyond S_TD on important vortex parameters including r_c, V_tmax, z …

Numerical Simulations Of Supersonic/ Hypersonic Flows In Compression Corners And A Hypersonic Flow Study Of Atmospheric Entry Of Mars Science Laboratory Capsule, Dexter Allen

McKelvey School of Engineering Theses & Dissertations

This thesis consists of two related parts. The first part is the study of supersonic/hypersonic flow in compression corners. The compression corners are simple geometries but rich in flow-features that can be challenging for accurate prediction of their flow fields in high-speed compressible flow using the Reynold-Averaged Navier-Stokes (RANS) equations in conjunction with a turbulence model. At higher degrees of corner angles, there exists a shock-boundary layer interaction region which includes a significant recirculation zone in the corner. In this thesis, experimentally available test cases for compression corner at Mach 3, 8, and 11 at various corner angles are modeled …

Field Flow Measurements For Pipe Installations With Non-Ideal Conditions, Jake Douglas

All Graduate Theses and Dissertations, Fall 2023 to Present

Accurate flow measurement data is necessary to effectively manage water resources. The purpose of this research is to investigate options to improve field flow measurement by investigating alternatives for calibrating flow meters installed in non-ideal piping. Typically, to accurately measure a flow rate using most types of flow meters, it is recommended that a straight section of pipe be installed immediately upstream and downstream of the flow meter to avoid flow fluctuations at the meter location. However, in many cases, flow disturbances upstream of the meter are unavoidable.

The performance of field flow measurements in non-ideal piping scenarios were studied …

Numerical Study In Wind Energy Extraction From Controlled Limit-Cycle Oscillations In Modified Glauert Airfoil, Ethan L. Deweese

Doctoral Dissertations and Master's Theses

Typically, wind energy harvesting technology employs wind turbines. Towards the goal of meeting increasing energy needs with renewable energy sources a novel wind energy harvesting scheme is considered, utilizing a modified Glauert (MG) airfoil experiencing aeroelastic limit cycle oscillation (LCO) from which energy may be extracted. Synthetic jet actuators (SJA)s are used along with the unique geometry of the MG airfoil to control flow separation and amplify the LCO and energy generation potential of the system. The discussed wind energy harvesting scheme could provide flexibility in allowing installations previously unsuitable to wind turbines due to geometric or low wind velocity …

Development Of Eagle3d Solver For Wall Modeled Les Of Transonic Flows, Spencer Moore

Doctoral Dissertations and Master's Theses

Wall modeled Large Eddy Simulation (LES) is an area of interest due to its ability to lower computational costs of LES simulation. Even with the application of wall models, LES still proves to have practicality issues when it comes to use in industry, due to the expertise, time, and computational resources required to get results. A case described by an axisymmetric transonic bump is explored utilizing the Embry-Riddle Aeronautical Universities in house unstructured finite volume multi-element CFD code, Eagle3D. Eagle3D, has been brought to the state of the art and validated against current research using this transonic bump case as …

Development Of Eagle3d Solver For Wall Modeled Les Of Transonic Flows, Spencer Moore

Doctoral Dissertations and Master's Theses

Wall modeled Large Eddy Simulation (LES) is an area of interest due to its ability to lower computational costs of LES simulation. Even with the application of wall models, LES still proves to have practicality issues when it comes to use in industry, due to the expertise, time, and computational resources required to get results. A case described by an axisymmetric transonic bump is explored utilizing the Embry-Riddle Aeronautical Universities in house unstructured finite volume multi-element CFD code, Eagle3D. Eagle3D, has been brought to the state of the art and validated against current research using this transonic bump case as …

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 …

Numerical Analysis Of A Multi-Stage Elastohydrodynamic Seal For Aircraft Engines, Md Wasif Hasan

Electronic Theses and Dissertations

At present, both governmental and private aviation enterprises are trying to develop aircraft that are swifter, more lightweight, and more cost-effective in order to maintain competitiveness on both the domestic and global stage. Continuous innovation and sustainability efforts are necessary to achieve advancements in aviation systems, such as fans, compressors, combustors, and turbines, as well as sub-systems, like engine seals. Advanced engine seals exhibit considerable potential in enhancing the engine's pressure ratio and cycle temperatures, leading to reduced engine weight, increased thrust, and improved fuel economy. In this study, a novel multistage seal idea has been proposed for the supercritical …

Development, Implementation, And Optimization Of A Modern, Subsonic/Supersonic Panel Method, Cory D. Goates

All Graduate Theses and Dissertations, Fall 2023 to Present

In the early stages of aircraft design, engineers consider many different design concepts, examining the trade-offs between different component arrangements and sizes, thrust and power requirements, etc. Because so many different designs are considered, it is best in the early stages of design to use simulation tools that are fast; accuracy is secondary. A common simulation tool for early design and analysis is the panel method. Panel methods were first developed in the 1950s and 1960s with the advent of modern computers. Despite being reasonably accurate and very fast, their development was abandoned in the late 1980s in favor of …

Applications Of Large Eddy Simulations To Novel Internal Combustion Concepts, Patrick O'Donnell

All Dissertations

Computational fluid dynamics (CFD) simulations of internal combustion engines (ICEs) are becoming an increasingly popular tool in the automotive industry to either explain experimentally observed trends or perform lower cost design iterations. The convenience of commercially available CFD software and advancements made in computing hardware have been the impetus behind this growing popularity. However, obtaining accurate results using these software packages is not a trivial process and requires an in-depth understanding of the underlying numerical methodology and sub models for various physical phenomena. Specific to the ICEs, CFD simulation often entails the use of models for detailed chemistry and combustion, …

Towards Cfd Investigations Into Particulate Air Pollution Of A Desert Urban Environment, Prosun Roy

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation has explored computational fluid dynamics (CFD) techniques for studying particulate air quality in the Las Vegas urban area. The dissertation is based on three research tasks: • High time-resolution fenceline air quality sensing and dispersion modeling for environmental justice-centered source attribution. (Chapter 2) • Pollen dispersion and deposition in real-world urban settings: A computational fluid dynamic study. (Chapter 3) • Effects of urban canopy parameterizations on modeling pollen dispersion and exposure. (Chapter 4) In Chapter 2, we investigate the facilitation of low-cost air quality sensors (LCAQS) and CFD technique on exposure assessment of environmental justice (EJ) communities and …

Stabilization Trajectory And Recovery System For High Altitude Weather Balloon Payloads (S.T.A.R.), Robert Canalas, Aaron Juan, Miles Nguyen, James Oblitas, Anne Paloma

Mechanical Engineering Senior Theses

Of the 657,000 global balloon launches each year, only 20% of payloads are recovered, leading to unsustainable business and environmental practices. This paper details the development and evaluation of the S.T.A.R. (Stabilization, Trajectory, and Recovery) system, which increases the recovery rate of weather balloon sensors by enabling ideal landing conditions. System testing concludes that S.T.A.R. is capable of housing weather sensors in a fully controllable glider capable of targeted landing. If properly scaled up and redesigned for mass production, the S.T.A.R. system increases weather-sensing equipment recovery for weather-reporting institutions around the world. Although the featured iterations consist of basswood, carbon …

Computational Analysis Of Steady Hypersonic Flow Fields Of Nasa Benchmark Geometries Utilizing Ansys Fluent, Aidan Murphy

McKelvey School of Engineering Theses & Dissertations

The Hypersonic International Flight Research Experimentation (HIFiRE) program explores and advances hypersonic aerospace systems by developing a multitude of test flight geometries and conducting experimental test flights to obtain data for use in validation of computational models and results. This study focuses on computational validation of heat flux, and calculation of static pressure profiles, skin friction coefficient profiles, and flow contours. The flow fields studied are for Mach number 7.18 and angles of attack (α) of 0° & 2°. These flow fields include many compressible flow features such as an expansion wave at the intersection of the cone and flat …

Drop Impact On Dry And Liquid Infused Substrates With Micro-Wells., Ahmed Nazrul Islam

Electronic Theses and Dissertations

Drop impact on different types of surfaces are important physical concepts that are routinely found in day-to-day life and such studies have immense application for various types of industries. One such important application of drop dynamics is in the field of aviation science which is concerned of very large freezing drizzle drops impacting on airplane wings. Such drops are known as supercooled large droplets (SLD), and they pose a great risk and have been long known to have caused notable accidents in the past. SLDs are liquid drops that can remain in the state of liquid phase and grow into …

Reynolds-Averaged Navier-Stokes Cfd Simulation Of High-Speed Boundary Layers, Michael Tullis

Mechanical Engineering Undergraduate Honors Theses

This paper presents an investigation of Reynolds-averaged Navier-Stokes (RANS) turbulence models used in computational fluid dynamics (CFD) simulations of boundary layer flow and heat transfer in high Mach number flows. This study evaluates an industry standard RANS turbulence model (k-omega SST) and a recently proposed modification to that model (Danis and Durbin [1]), and quantifies the accuracy for predicting high Mach number boundary layer flow. The test cases were previously documented by Duan et al. (2018), who used direct numerical simulation (DNS) to calculate boundary layer flow of an ideal gas over a flat plate at freestream Mach numbers ranging …

Computational Modeling Of Patterned Membranes And Spacers For Improved Hydrodynamics And Fouling Reduction In Reverse Osmosis Water Treatment Processes, Zuo Zhou

All Dissertations

My research goal is to discover ways to improve the hydrodynamics of reverse osmosis (RO) membrane systems through creative membrane surface patterning and spacer designs. Since concentration polarization (CP) usually promotes membrane fouling, improving hydrodynamics would result in reduced fouling and better membrane performance. With computational fluid dynamics (CFD), we can explore dozens or even hundreds of models with different geometries and boundary conditions. Through plotting their velocity profile, streamlines, shear stress, pressure profile, concentration profile, and so on, we can determine which design would lead to the best performance.

At first, patterned membranes were evaluated and compared with flat …

Prediction & Active Control Of Multi-Rotor Noise, Samuel O. Afari

Doctoral Dissertations and Master's Theses

Significant developments have been made in designing and implementation of Advanced Air Mobility Vehicles (AAMV). However, wider applications in urban areas require addressing several challenges, such as safety and quietness. These vehicles differ from conventional helicopter in that they operate at a relatively lower Reynolds number. More chiefly, they operate with multiples of rotors, which may pose some issues aerodynamically, as well as acoustically. The aim of this research is to first investigate the various noise sources in multi-rotor systems. High-fidelity simulations of two in-line counter-rotating propellers in hover, and in forward flight conditions are performed. Near field flow and …

The Numerical Study Of Aeroacoustics Performance Of Wings With Different Wavelength Leading-Edge Tubercles, Youjie Zhang

Honors Undergraduate Theses

The leading-edge tubercle is a type of airfoil modification that inspired by the humpback whale. It was found that the aerodynamic performance of the wing would increase compared to the wing without tubercles. In the past several years, a lot of numerical and experimental studies have been accomplished to explore this leading-edge modification. Besides the aerodynamic performance change, this research explores the aeroacoustics behavior of airfoils with leading-edge tubercles. A numerical study based on Computational Fluid Dynamics (CFD) is established, and simulations using Star CCM are accomplished based on reasonable set-ups. The airfoil chosen to create the wing is NACA …

A Computational Fluid Dynamic Analysis Of Oxyacetylene Combustion Flow For Use In Material Response Boundary Conditions, Craig Meade

Theses and Dissertations--Mechanical Engineering

Oxyacetylene torches are used in the aerospace industry and research to test thermal protection system materials (TPS) due to their high flame temperatures and high heat flux capabilities. The purpose of this work is to determine a combustion model to accurately simulate the high temperature flow of an oxyacetylene torch. The flow conditions around a sample material can then be used as boundary conditions when modeling TPS material response. Two separate combustion models with equilibrium chemistry were investigated using ANSYS Fluent™; the Eddy-Dissipation Model, and the Partially Premixed model.The results of this study are compared to existing experiments for validation.

Cfd Analysis For Beyond Bubbly Gas-Liquid Two-Phase Flows In A Large Diameter Pipe, Sungje Hong

Doctoral Dissertations

"Due to the complexity of multiphase flow phenomena, numerical analysis for multiphase turbulent flow is not as reliable as single-phase computational fluid dynamics (CFD). A literature review has revealed that the current efforts on multiphase flow simulation have focused on small diameter channels under very restricted flow conditions and have been conducted without identifying some important procedures. To expand CFD applications to a wide range of two-phase flow conditions in large diameter channels, this study aims to validate the current CFD models for vertical concurrent air-water two-phase flow simulations beyond bubbly flows. First, a numerical model developed to describe dynamical …

Development Of A Quasi-Dimension Gci Combustion Model Aided By Cfd, Jinsu Kim

Graduate Theses, Dissertations, and Problem Reports

Advanced combustion strategies have been proposed to improve fuel efficiency while minimizing exhaust emissions. Gasoline compression ignition (GCI) combustion featuring partially premixed compression ignition (PPCI) and diffusion combustion has been recognized as an attractive, viable combustion strategy for its potential and advantages over conventional diesel and gasoline engines. The optimization of the GCI engine system requires the development of a quasi-dimensional GCI combustion model capable of simulating GCI combustion while requesting less computational burden than CFD simulation, which is very critical in engine system simulation. This study developed a quasi-dimension, phenomenological combustion model for PPCI and diffusion combustion to facilitate …

Computational Fluid Dynamics Modeling Of Hemodialysis In Patients With An Arteriovenous Fistula, Maximilian Roth

McKelvey School of Engineering Theses & Dissertations

With the advent of arteriovenous fistula (AVF) for use in hemodialysis, the anastomosis built for such use has become a central point of the study to understand the flow and wall shear stresses in such a system since very large wall shear stresses can lead to arterial/vein rupture. Considering the commonly used creation site of an anastomosis as connecting the radial artery to the cephalic vein, a model is created to calculate the wall shear stresses across various components of the system. The model depicts a connection of the specified vein and artery bridged together allowing the increase in blood …

Predictive Capabilities Of Laminar-Turbulent Transition Models For Aerodynamics Applications, Jared Alexander Carnes

Doctoral Dissertations

Laminar-turbulent boundary-layer transition has a demonstrable impact on the performance of aerospace vehicles. The ability to accurately predict transition is integral to properly capturing relevant flow physics. Traditionally, computational fluid dynamics simulations are performed fully turbulent, meaning that laminar flow is neglected. This, however, can result in errant predictions of vehicle performance as quantities such as skin-friction drag may be overpredicted. Resultingly, development of Reynolds-averaged Navier-Stokes transition models has seen significant attention over the last decades in order to model transition and realize the performance improvements of laminar flow.

In this work, the behaviors of several different transition-prediction methods are …

Using Computational Fluid Dynamics To Predict Flow Through The West Crack Breach Of The Great Salt Lake Railroad Causeway, Michael Rasmussen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Great Salt Lake in Utah, USA, is a terminal, saline lake and is divided into two primary sections (northern and southern) by an east-to-west railroad causeway. Shortly after completion of the earth-fill causeway in the late 1950s, the two sections became dramatically different with differences in water surface elevation and water density. These differences cause the formation of a unique flow behavior commonly referred to as a density-driven exchange flow or bi-directional flow; a behavior observed in other lake and ocean settings where two fluids of differing densities interact. Measuring these exchange flows is a priority for lake managers …

Analysis Of Turbulent Flow Behavior In Helicopter Rotor Hub Wakes, Forrest Mobley

Masters Theses

The rotor hub is one of the most important features of all helicopters, as it provides the pilot a means for controlling the vehicle by changing the characteristics of the main and tail rotors. The hub also provides a structural foundation for the rotors and allows for the rotor blades to respond to aerodynamic forces while maintaining controllability and stability. Due to the inherent geometry and high rate of rotation, the rotor hub in its current form acts a large bluff body and is the primary source of parasite drag on the helicopter, despite its relatively small size. The rotor …

Fire Simulation And Analysis Of A Switchgear Cabinet Fire And Its Effects On Cable Trays, Yalcin Meraki

Masters Theses

Switchgear rooms are crucial in containing essential equipment such as cabinets and cable trays in case of a possible fire. There are three fire model classes which are algebraic models, zone model, and computation fluid dynamics model (CFD). PyroSim software, a visual user interface for the Fire Dynamics Simulator (FDS) developed at the National Institute of Standards and Technology (NIST), was used for simulation by using the CFD. Two different 464 kW and 1002 kW heat release rate (HRR) values were used under the same conditions for the fire scenario. By considering a fire scenario, the fire ignited due to …

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 …

Using Experiments, 3d Scanning, And Computational Fluid Dynamics To Analyze Variance In Minor Loss Coefficients, Adam B. Pack

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As water moves through pipes, it loses energy. The energy losses are due to friction and the minor losses associated with various pipe fittings, which change the direction of flow. Pipe bends, or elbows, are a common pipe fitting and a significant source of energy loss in piping systems. This research was performed to better understand the variability of energy loss due to different pipe elbow designs and to investigate methods to replicate these losses using numerical simulations.

Eight pipe elbows, all 3-inch, 90-degree, schedule 40 PVC elbows that vary by radius of curvature and/or end connection type, were tested …

Fuel Injector Design Of A Hypersonic Jet Engine Using Computational Fluid Dynamics, Melissa Rose Mercado

UNLV Theses, Dissertations, Professional Papers, and Capstones

The development of hypersonic airbreathing engines, such as a supersonic combustion ramjet, or scramjet, are implemented for flight Mach numbers over 5 where combustion must occur in supersonic conditions. The advancement of scramjet propulsion has led to favored usage over rocket propulsion systems for in atmosphere applications due to their lighter weight, higher specific impulse, and greater maneuverability [1]. The combustor section of a scramjet engine houses the fuel injectors. Fuel is injected into the supersonic flow with the main objective of achieving rapid and thorough fuel-air mixing because the residence time in the combustion chamber has a timescale of …

Computational Study Of Dense Gas Dispersion In Urban Areas, Rasna Sharmin

All Dissertations

A series of steady-state simulations have been conducted to investigate removal of dense gas from a simple square canyon formed between two square cross-section obstacles. Due to urbanization and industrialization, there always lies a high risk of exposure to harmful pollutants which can result from accidental release of toxic gasses. Those are often denser than the atmosphere. and can easily get trapped in between buildings in urban canopies. It is important to have full understanding of flushing mechanism of dense fluid inside urban canopies by steady turbulent flow because the exposure to these toxic dense gasses can be catastrophic. There …