Engineering Commons^™

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 …

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 …

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 …

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 …

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 …

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.