Aerospace Engineering Commons^™

Bio-Inspired Electroactive Polymer (Eap) Sensors For Surface And Canal Flow Sensing In Dynamic Environments, Nazanin Minaian

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nature can often create some of the most efficient and elegant solutions to complex problems, and engineering stands to benefit greatly from these time-tested designs. One of the more sophisticated examples of this is the lateral line system in fish: a distributed network of superficial and canal neuromasts that enables aquatic species to detect fluid disturbances with remarkable precision. This dissertation leverages that biological framework to explore the potential of electroactive polymers (EAPs), aiming not just to replicate structure, but to emulate function.Two classes of EAPs form the basis of this work: electroactive plasticized polymer gels (EPPGs) and ionic polymer-metal …

Development Of A Passive Drag Reduction Modification For The 25° Ahmed Body Using Large Eddy Simulation, Skylar Polek

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the field of automotive aerodynamics, the Ahmed body is a generic vehicle-shaped bluff body which is meant to generalize the rear end of fastback and hatchback vehicles. Specifically, an Ahmed body with a rear slant angle of 25° has seen common use due to its resemblance of common rear windshield shapes as well as its notoriously complex wake structure. This research focuses on simulating the flow over a 25° in various situations with an ultimate goal of drag reduction. First, a simple benchmark of the k-ω shear stress transport (SST), large eddy simulation (LES) with the Smagorinsky-Lilly subgrid scale …

Performance Effects Of Dissociated Hydrogen In Nuclear Thermal Propulsion Engines, Richard Adam Gorrell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nuclear thermal propulsion (NTP) research considers hydrogen dissociation as negligible to design and analysis of propulsion engines. This study reintroduces chemically reacting flow to NTP engine analysis for investigation of the dissociation effect on engine performance. A first-principles approach observes the basic chemical mechanism and reaction within the high-speed, high-temperature NTP flow to baseline expected atomic hydrogen levels and validate equilibrium. A surface reaction study looks into hydrogen absorption through dissociation and its effect on the boundary layer, and bulk flow. For total performance, the resulting dissociated flow is analyzed through nozzle expansion and performance metrics calculated.

All historic reactor …

Numerical Investigations Of Sco2 Compressor Aerothermodynamics Using A Streamline Curvature Based Throughflow Method, Victor Quintanilla

UNLV Theses, Dissertations, Professional Papers, and Capstones

Supercritical carbon dioxide (sCO₂) has emerged as a promising working fluid for the Brayton power cycle, offering enhanced efficiency due to the high density and low viscosity of carbon dioxide (CO₂) near the critical point. A critical component of the sCO₂ Brayton cycle is the turbomachinery, namely the compressor, which significantly contributes to the efficiency enhancement in the sCO₂ Brayton cycle owing to reduced compression work requirements. Its primary function involves elevating the fluid's pressure, effectively priming it for the subsequent heat addition process from a thermal energy source. However, despite its advantages, challenges …

A Dynamic Scoring Methodology For Morphing Airfoil Designs With Application To A Stalling Scenario, Stone Wachs

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shape Changing Airfoils (SCAs) are a developing technology with potential aircraft applications. Leading aerospace corporations are actively researching SCA capabilities. The necessity for this technology stems from the requirement of control surfaces for safe aircraft control. However, the process of testing and determining optimal SCA designs can be costly and time-consuming. While methodologies exist, they often require specific scenario examples and lack a standard approach. To address this issue, a standardized methodology is needed that can be applied to various applications and scenarios. This methodology consists of computational/experimentally produced data for airfoils, a subjective and strategic scoring equation, an algorithmic …

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 …

Simulating Condensation In The Theory Of Classical Nucleation, David Vallet

UNLV Theses, Dissertations, Professional Papers, and Capstones

The scope of this thesis is to numerically investigate condensation that occurs in transonic and supersonic flows. Condensation shocks are a phenomenon that occurs within converging-diverging nozzles. There are many applications forconverging-diverging nozzles, such as thermovapour compressors (TVC), which are largely used for desalination. As water resources become more precious within the western United States there is a need to develop cost effective solutions for cleaning water. Steam generator power stations are another application where enhanced simulations and accuracy of design could improve efficiency and save on carbon emissions. Traditionally, numerical designs of transonic flows have been conducted with either …

Mathematical Modeling: Finite Element Analysis And Computations Arising In Fluid Dynamics And Biological Applications, Jorge Reyes

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is often the case when attempting to capture real word phenomena that the resulting mathematical model is too difficult and even not feasible to be solved analytically. As a result, a computational approach is required and there exists many different methods to numerically solve models described by systems of partial differential equations. The Finite Element Method is one of them and it was pursued herein.This dissertation focuses on the finite element analysis and corresponding numerical computations of several different models. The first part consists of a study on two different fluid flow models: the main governing model of fluid …

A Mechanically Intelligent Hosing-Drone, Blake Hament

UNLV Theses, Dissertations, Professional Papers, and Capstones

This manuscript presents a ”mechanically intelligent” approach to designing a Hosing-Drone for heavy-duty pressure washing. Spraying a hose creates strong reaction forces and torques. Previously demonstrated spraying robots are over-engineered to be very massive with huge inertias. These high inertias ”wash out” the reaction from the spraying. In the proposed approach, the contributions from all observable fluid dynamics, fluid structure interactions, and aerodynamics are studied individually and for the coupled system. Experimental data is collected and fit to dynamic models. These models are used to design a smaller, lighter, more agile vehicle than has been previously demonstrated. An impedance controller …

Enhancements To Nuclear Thermal Propulsion Rockets, Kimberly Gonzalez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nuclear thermal rocket propulsion has been proposed as a highly efficient technology for space vehicles traveling from earth orbit to the moon, Mars, and other locations in the solar system. With twice the performance of a chemical rocket, nuclear thermal propulsion (NTP) uses the thrust produced by heating hydrogen gas within a thermal nuclear reactor where the exhaust is then passed through a de Laval nozzle to produce supersonic flow. NTP engines were the subject ofthe NERVA experiments at the Nevada Test Site in the 1970’s, and they produced a specific impulse of up to 900 seconds which is almost …

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 …

Carbon Fiber Coil Spring Characterization And Manufacturing, Cooper Madrazo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Helical coil springs are used in many mechanical design applications including industrial machines, devices, and vehicle suspension systems. It is desirable to minimize the weight of vehicle suspension systems as this can improve performance and handling. Most vehicle suspension coil springs are made from solid steel alloys or other metallic materials. Significant weight savings could be achieved if the metallic material were replaced by high performance fiber reinforced polymer composites. However, the coil spring geometry is a difficult manufacturing challenge for composite materials. The goal of this thesis was to investigate efficient and low-cost manufacturing methods to produce light-weight polymer …

Viability Of Energy And Fuel Sources For Interstellar Travel; Design And Feasibility Of The Construction Of Manned Interstellar Space Shuttles, Lukas Mittelman

UNLV Theses, Dissertations, Professional Papers, and Capstones

The importance of proving the viability of interstellar transport and addressing its potential hazards and pitfalls is immense. If we do not look toward the future and examine what could be waiting for us, we are doing our children, our children’s children, and so on, a disservice. Here we must attempt to lay the groundwork for our future scientists, engineers, and adventurers. Asking and answering questions like, which propulsion and energy systems must we incorporate to send us through the cosmos? Will we utilize technologies known today, such as fossil fuel rockets, fission or fusion rockets, and antimatter drives (pion …

The Chime Fast Radio Burst Population Does Not Track The Star Formation History Of The Universe, Rachel C. Zhang, Bing Zhang

Physics & Astronomy Faculty Research

The redshift distribution of fast radio bursts (FRBs) is not well constrained. The association of the Galactic FRB 200428 with the young magnetar SGR 1935+2154 raises the working hypothesis that FRB sources track the star formation history of the universe. The discovery of FRB 20200120E in association with a globular cluster in the nearby galaxy M81, however, casts doubts on such an assumption. We apply the Monte Carlo method developed in a previous work to test different FRB redshift distribution models against the recently released first CHIME FRB catalog in terms of their distributions in specific fluence, external dispersion measure …

Computational Sodium Heat Pipe Simulation In Three Dimensions For Transient Nuclear Reactor Analysis With Variable Surface Heat Flux, Valerie Jean Lawdensky

UNLV Theses, Dissertations, Professional Papers, and Capstones

Heat pipes are used to transfer heat through phase change in a liquid/vapor contained in a metal tube. They are passive devices that require no pumps to circulate the fluid and can transfer heat far more efficiently than a solid copper rod of the same diameter. They are commonly used in laptop computers where copper heat pipes filled with water take heat away from the CPU and transfer the heat to air through a heat exchanger. Heat pipes were also used in the Kilopower nuclear reactor where higher temperatures required sodium as the working fluid with stainless steel tubes. Computer …

Streaming Instability With Multiple Dust Species-Ii. Turbulence And Dust-Gas Dynamics At Non-Linear Saturation, Chao-Chin Yang, Zhaohuan Zhu

Physics & Astronomy Faculty Research

The streaming instability is a fundamental process that can drive dust-gas dynamics and ultimately planetesimal formation in protoplanetary discs. As a linear instability, it has been shown that its growth with a distribution of dust sizes can be classified into two distinct regimes, fast-and slow-growth, depending on the dust-size distribution and the total dust-To-gas density ratio . Using numerical simulations of an unstratified disc, we bring three cases in different regimes into non-linear saturation. We find that the saturation states of the two fast-growth cases are similar to its single-species counterparts. The one with maximum dimensionless stopping time τs,max = …

Plasma Aerodynamics: Experimental Quantification Of The Lift Force Generated On An Airfoil Using Plasma Actuation To Estimate Power Requirements In Small Uav Applications, Getachew Ashenafi

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research addressed the amount of electric power required to induce specific changes in lift force using a NACA 2127 airfoil with a chord length of ~28 mm, connected to a micro load cell, in a wind tunnel of 103 square centimeter cross-section. A DBD plasma actuator supplied by a ZVS driven high voltage pulsed DC circuit, operating at a frequency of 17.4 kHz, was utilized for voltages of up to 5000 V. Two configurations of electrode gapping were compared to determine the efficient use of power. The configuration with a gap of ~1 mm between the upstream and downstream …

Numerical And Experimental Analysis Of Air-Cooled Condensers, Kaipo Kekaula

UNLV Theses, Dissertations, Professional Papers, and Capstones

The scope of this project is to numerically and experimentally dry cooling process in air-cooled condensers (ACCs) designed for concentrated solar power (CSP) applications. This effort is driven by the growing economic and political pressure to reduce water consumption during power generation due to limited water resources in the arid geographic climate of the southwestern United States. A computational approach is used in conjunction with experimental validation to gain a more complete understanding of these systems.

Traditionally research into ACCs have been largely limited to air-side heat transfer modelling as it accounts for a large portion of the total thermal …

Discrete Vortex Modeling Of Aerodynamic Flutter Of A Flat Plate With Damped Oscillations, Emma Chao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerodynamic flutter is the unstable oscillation of a body caused by the interaction of aerodynamic forces, structural elasticity, and inertial effects induced by vortex shedding. Current models of this phenomenon require finite element analysis and extensive computational power and processing time. The purpose of this study was to develop and validate a program that is faster and more efficient than existing approaches by using the discrete vortex method (DVM). By reducing the complexities of flutter to the shedding of vortices in an inviscid model of a two-dimensional flat plate with a torsional spring constant at its center, this phenomenon can …

Comparison Of Signaling Profiles In The Low Dose Range Following Low And High Let Radiation, Deepa M. Sridharan, Lung-Chang Chien, Francis A. Cucinotta, Janice M. Pluth

Environmental & Global Health Faculty Research

During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82–6, was exposed to a range of lower doses (0.05–0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si …

Performance Modeling Of Supercritical Carbon Dioxide Zigzag-Channel Printed Circuit Heat Exchangers, Katrine Birgitte Bennett

UNLV Theses, Dissertations, Professional Papers, and Capstones

Supercritical carbon dioxide (sCO2) is currently being studied as the working fluid in power producing Brayton cycles due to its excellent physical and thermodynamic properties, especially near the critical point. Printed circuit heat exchangers (PCHEs) are being considered for use as condensers and recuperators for this purpose due to their high strength and compact designs. Many experimental and numerical studies are being conducted to characterize and optimize sCO2 PCHE operation and develop correlations to describe their thermal-hydraulic performance. Additionally, a few experimental and numerical structural assessments of these PCHEs have been conducted, but all have been somewhat limited due to …

Numerical Study Of Spacer Grid Geometry In A 5 X 5 Nuclear Fuel Rod Bundle, Wan Chuan Fan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reactor fuel rod bundles serve as the primary heat source in light water reactors (LWRs), commonly found in the aforementioned PWR plants. The fuel rod bundles’ structure consists of a collection of fuel rods put into a parallel grid configuration. The bundles also include fuel rod spacers, which hold the fuel rods in place, in accordance with the grid. Repeating structures of the fuel bundles create the meta-structure in the reactor. In other words, the grid configuration repeats until it fills the entire space of the reactor. This results in reactor fuel rods suspended in the working fluid domain, oriented …

Assessing Simulated Transmissivity In Numerical Flow Models Of Complex Hydrogeology, Afan Tarar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accurately extracting a meaningful transmissivity, a target value within one order of magnitude of field estimates, in numerical models poses a significant challenge when modeling complex groundwater systems. Aquifer transmissivity is directly proportional to the aquifer thickness and the estimated aquifer hydraulic conductivity. In complex geologic conditions (especially in fractured systems) with multiple heterogeneous and anisotropic hydrogeologic units, transmissivity can vary over several orders of magnitude.

To extract a meaningful value of transmissivity from a numerical model, a simple five-layer MODFLOW model was constructed. Each layer in the model was assigned a fixed hydraulic conductivity and thickness. The model simulates …

Numerical Analysis And Fluid Flow Modeling Of Incompressible Navier-Stokes Equations, Tahj Hill

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Navier-Stokes equations (NSE) are an essential set of partial differential equations for governing the motion of fluids. In this paper, we will study the NSE for an incompressible flow, one which density ρ = ρ0 is constant.

First, we will present the derivation of the NSE and discuss solutions and boundary conditions for the equations. We will then discuss the Reynolds number, a dimensionless number that is important in the observations of fluid flow patterns. We will study the NSE at various Reynolds numbers, and use the Reynolds number to write the NSE in a nondimensional form.

We will …

Adaptive And Supertwisting Adaptive Spacecraft Orbit Control Around Asteroids, Keum W. Lee, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

This paper addresses the development of control systems for the orbit control of spacecraft around irregularly shaped rotating asteroids with uncertain parameters. The objective is to steer the spacecraft along prescribed orbits. First, a nonlinear adaptive law for orbit control was designed. This was followed by the design of a supertwisting adaptive (STWA) control system. In the closed-loop system, which includes the adaptive law or the STWA law, all the signals remain bounded, and the trajectory tracking error asymptotically converges to zero for any initial condition. Finally, under the assumption of boundedness of the derivative of the uncertain functions of …

The Potential Science And Engineering Value Of Samples Delivered To Earth By Mars Sample Return, David W. Beaty, Monica M. Grady, Harry Y. Mcsween, Elliot Sefton-Nash, B. L. Carrier, Francesca Altieri, Yuri Amelin, Eleonora Ammannito, Mahesh Anand, Liane G. Benning, Janice L. Bishop, Lars E. Borg, Dale Boucher, John R. Brucato, Henner Busemann, Kathleen A. Campbell, Andrew D. Czaja, Vinciane Debaille, David J. Des Marais, Michael Dixon, Bethany L. Ehlmann, Jack D. Farmer, David C. Fernandez-Remolar, Justin Filiberto, Jennifer Fogarty, Daniel P. Galvin, Y. S. Goreva, Lydia J. Hallis, Andrea Dawn Harrington, Elisabeth M. Hausrath, Chris D.K. Herd

Geoscience Faculty Research

Executive summary provided in lieu of abstract.

Cfd Modeling Of Smoke Movement In An Atrium, Robin Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is to better understand the behavior of smoke movement in an atrium. Thus gives first responders and civilians in and out of building a better understanding

With the advancements of modern technology, computers and softwares make simulation models possible such as fire models to simulate fire and smoke movements. In this paper, a computational fluid dynamic (CFD) software Fire Dynamic Simulator (FDS) is used to conduct a series of atrium tests to investigate the effectiveness of smoke exhaust systems. FDS solves the Navier-Stokes equations appropriate for low speed flows (Ma < 0.3) with an emphasis on smoke, heat transport and CO2 concentrations from fires. The default turbulence model used in FDS simulation is the Large Eddy Simulation (LES), which is the solution of Navier-Stokes equations at low speed.

The compartment tested was 9 …

Finite-Time Sliding Mode And Super-Twisting Control Of Fighter Aircraft, Kaushik Raj, Venkatesan Muthukumar, Sahjendra N. Singh, Keum W. Lee

Electrical & Computer Engineering Faculty Research

The development of two nonlinear robust higher-order flight control systems for roll-coupled maneuvers of fighter aircraft with uncertain parameters is discussed in this article. The objective is to independently control the output variables (roll angle, pitch angle and sideslip angle) using aileron, elevator and rudder control surfaces. For a nominal model of aircraft, first a finite time stabilizing (FTS) control law, based on the notion of geometric homogeneity, is designed. Then for robust control in the presence of parameter uncertainties, (i) a discontinuous sliding mode (DSM) control law and (ii) a super-twisting (STW) continuous control law is designed. It is …

Linear And Nonlinear Adaptive Attitude Control Of Asteroid-Orbiting Spacecraft Using State Feedback And Output Feedback, Nicholas Moya

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents the derivation of both a linear and nonlinear adaptive control law for the attitude states of a spacecraft in orbit around rotating asteroids. The asteroid is assumed to be irregularly shaped and in an elliptical orbit around the sun. The linearized, time-varying spacecraft model will assume to include unknown parameters and will have external disturbances present. The objective is to control the roll, pitch, and yaw angle trajectories of the spacecraft such that they track desired reference trajectories. To achieve this, the control law will be composed of (1) a feedback controller, sufficiently robust to disturbance such …

The Future Of Construction As It Applies To The Colonization Of The Moon And Mars, Julian Prestia

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goals of this research are:

1. To compile a comprehensive list of all the viable known solutions (and early stage potential solutions) to the issues related to constructing permanent, sustainable, and safe structures for human colonies on our moon and Mars,

2. Determine the most effective potential solutions, and

3. Further develop these ideas as to assist in further space endeavors.

This proposed paper will assist space experts in determining the best next steps in the development of deep-space travel and colonization technologies. Preliminary research has identified several key problems associated with establishing space colonies. They are as follows: …