Aerospace Engineering Commons^™

The Breakup Of Rp-2 Liquid Fuel Droplets In A Detonation Field, Daniel Dyson

Electronic Theses and Dissertations, 2020-2023

Experimentally obtained droplet breakup patterns are presented for RP-2 liquid fuel droplets in the environment behind a detonation wave. To the best of our knowledge, this data is the first of its kind to examine the fundamental interactions between detonation waves and an individual fuel droplet. The experiments presented here are expected to support the ongoing effort of creating accurate models of droplet breakup in a variety of environments, which in turn will lead to enhanced predictions of rotating detonation engine performance, improved safety considerations for facilities operating in hazardous conditions, and new knowledge in energetics, hypersonics, and explosion dynamics …

Recent Analytic Development Of The Dynamic Q-Tensor Theory For Nematic Liquid Crystals, Xiang Xu

Mathematics & Statistics Faculty Publications

Liquid crystals are a typical type of soft matter that are intermediate between conventional crystalline solids and isotropic fluids. The nematic phase is the simplest liquid crystal phase, and has been studied the most in the mathematical community. There are various continuum models to describe liquid crystals of nematic type, and Q-tensor theory is one among them. The aim of this paper is to give a brief review of recent PDE results regarding the Q-tensor theory in dynamic configurations.

Autoignition Delay Time Measurements And Chemical Kinetic Modeling Of Hydrogen/Ammonia/Natural Gas Mixtures, Jessica Baker

Electronic Theses and Dissertations, 2020-2023

In recent years, hydrogen-carrying compounds have accrued interest as an alternative to traditional fossil fuels due to their function as zero-emission fuels. As such, there is interest in investigating hydrogen-carrying compounds to improve understanding of the fuels' characteristics for use in high pressure systems. In the current study, the oxidation of ammonia/natural gas/hydrogen mixtures was carried out to study CO formation profiles as well as the ignition delay times behind reflected shock waves in order to refine chemical kinetic models. Experiments were carried out in the University of Central Florida's shock tube facility by utilizing chemiluminescence to obtain OH* emission …

Shock Tube And Gas Dynamic Design Considerations And Implementation For Extended Test Times, Jacklyn Higgs

Electronic Theses and Dissertations, 2020-2023

A new shock tube test section has been designed and manufactured for the purpose of increasing the test time and expanding the applications of the shock tube for a multitude of ongoing and future projects. One purpose for the test section extension is to allow for flow visualization of droplets impacted by a shock wave for the interaction of hypersonic vehicles and atmospheric disturbances. Another purpose is to measure behind the incident shock to capture the chemical kinetics for a high-altitude environment and low-pressure, high-temperature space applications. This new test section contains 24 round optical ports for laser spectroscopy for …

Investigating The Effect Of Cmas Infiltration On Residual Stress Of High Temperature Ceramic Coatings For Turbine Engines Using 3d Confocal Raman Spectroscopy, Zachary Stein

Electronic Theses and Dissertations, 2020-2023

Calcium-magnesium-aluminosilicates (CMAS), such as sand or volcanic ash, are ingested by aircraft jet engines during operation. CMAS then becomes molten while traveling through the combustor of the engine before depositing onto turbine blades within the turbine section of the engine. The molten CMAS melt infiltrates and interacts with the high temperature ceramic coated turbine blades. This infiltration increases coating stiffness and promotes coating phase destabilization, encouraging micro-crack formation and increasing the risk of spallation. Thermomechanical effects from CMAS infiltration were mapped over time with confocal Raman spectroscopy. The residual stresses within infiltrated 7YSZ EB-PVD coatings were captured with microscale resolution. …

A Decoupled Engineering Methodology For Accurate Prediction Of Ablative Surface Boundary Conditions In Thermal Protection Systems, Justin Cooper

Theses and Dissertations--Mechanical and Aerospace Engineering

The main objective of the present work is to demonstrate a method for prediction of aerothermal environments in the engineering design of hypersonic vehicles as an alternative to the current heritage method. Flat plate and stagnation point boundary layer theory require multiple assumptions to establish the current engineering paradigm. Chief among these assumptions is the similarity between mass and heat transfer. Origins of these assumptions are demonstrated and their relationship to conservative engineering design is analyzed, as well as conditions where they possibly break down. An alternative approach for assessing aerothermal environments from the fluid domain is presented, which permits …

Numerical And Scaling Study On Application Of Inkjet Technology To Automotive Coating, Masoud Arabghahestani Dr.

Theses and Dissertations--Mechanical and Aerospace Engineering

A thorough literature review identified lack of precision control over quality of droplets generated by the currently available industrial sprayers and a growing need for higher quality droplets in the coating industry. Particularly, lack of knowledge and understanding in continuous inkjets (CIJ) and drop-on-demand (DOD) technologies is identified as significant. Motivated by these needs, this dissertation is dedicated to computational fluid dynamics (CFD) and scaling studies to improve existing inkjet technologies and develop new designs of efficient coating with single and/or multiple piezoelectric sensors to produce on-demand droplets. This dissertation study aims at developing a new DOD type coating technology, …

Experimental Investigation Of Roughness And Blowing Effects Over Ablator-Like Surfaces, Colby Borchetta

Theses and Dissertations--Mechanical and Aerospace Engineering

Two separate experiments using PIV were carried out to investigate the effects of
roughness and blowing over surfaces geometrically similar to ablation materials used for atmospheric re-entry. The first, water tunnel experiments, employed a dimpled surface similar to AVCOAT, while the second set was completed in a wind tunnel with a material similar to PICA. For the first set, the flow with blowing becomes destabilized, and more disorganized. The blowing disrupts the relatively simple vorticity shedding process and significantly modifies momentum transport via interaction of detached structures. Flow structure and their modifications were examined with a sPOD analysis. The focus …

Quantification Of The Aerodynamic Drivers Of A Deployable Propeller, David Malyszek

Electronic Theses and Dissertations, 2020-2023

With the use deployable drones becoming more common research into their improvement is necessary. Deployable drones that are launched from tubes have size limits on the diameter of the propeller during launch and storage. The purpose of this research is to develop deployable propeller blades for practical uses, such as tube launched propeller driven drones and easier to transport wind turbine blades. A deployable propeller will allow for the utilization of larger propellers when a large non-deployable blade isn't an option. Because deployable propellers need to fold, the deployable propeller blades were designed to be hollow and with a slit …

Experimental Study Of Wall Bounded Harbor Seal Whisker Inspired Pin Geometries, Anish Prasad, Mark Ricklick

Publications

Conventional cylindrical/elliptical pins are one of the most widely used geometries in convection cooling systems and are used in the internal cooling of gas turbine blades and other applications, as they promote better heat transfer at the expense of large pressure losses and unsteadiness in the flow. The need to reduce pressure drop and maintain the heat transfer rates are a pressing requirement for a variety of industries to improve their cooling efficiency. One such prominent field of research is conducted in optimizing the design of pin geometries. In this study, a harbor seal whisker inspired geometry is being studied …

Co2 Based Parachute Deployment, Anthony M. S. Settlemier, Nicholas Motter

Williams Honors College, Honors Research Projects

This paper describes the design process of a CO2 based parachute deployment system for the Akronauts Rocket Design team, with particular emphasis on the selection of methodologies of deployment as well as design iteration. The objective was to create a fully mechanical system in order to replace the black powder based systems that were used previously by the team.

Emphasis was put in creating a system that would function well at higher altitudes while also preventing damage to the parachute during deployment. This system emphasizes robustness under launch conditions.

Modelling Air Quality In An Aircraft Passenger Cabin Using Health Care Standards, Bert Silich

International Journal of Aviation, Aeronautics, and Aerospace

The interest in aerosol contamination of aircraft passenger cabins has increased since the onset of the COVID-19 pandemic. Mathematical models have been developed to help describe how an aerosol behaves in a closed space. The number of infectious particles inhaled is of scientific interest because it can be related to the risk of getting ill from a pathogen. The data required to calculate these results is often difficult to obtain in real world settings. In fact, particle inhalation details are not obtained in the day-to-day routine of a health care environment and are they not required to maintain safety. Hospital …

Aerodynamic Characterization Of An Elliptical Fairing In The Wake Of A Bluff Body, Luis Amaya

Electronic Theses and Dissertations, 2020-2023

Aerodynamic optimization is a key step in designing planes, cars, and even buildings. Numerical modeling is used to automate the optimization process and can use different methods to iterate through designs. In this process, consideration of the starting design is paramount as a poor choice can use up computational time and effort. Often, these designs are made with the intention of being out in the open, for which studies on shape variations in freestream situations abound. However, for the case where an object must be placed in the wake of another, there is little research. The study presented here aims …

Editorial For The Special Issue On Micromachines For Non-Newtonian Microfluidics, Lanju Mei, Shizhi Qian

Mechanical & Aerospace Engineering Faculty Publications

In lieu of an abstract, this is an excerpt from the first page.

Microfluidics has seen a remarkable growth over the past few decades, with its extensive applications in engineering, medicine, biology, chemistry, etc [...]

Aerodynamic Analysis Of Damage State Missiles Using Overset Meshing Techniques For Application To Computational Fluid Dynamics Simulation, Jonathan A. D'Alessio

Graduate Theses, Dissertations, and Problem Reports (ETD)

Significant research over the years has aimed to redefine the flight capabilities of aircraft after sustaining structural damage to critical components. Flight survivability and controllability are key areas of concern when designing fault-tolerant flight control systems to handle a wide range of potential scenarios. However, there is a lack of research on the impact of physically damaged missile systems. Missile counter-defense and intercept capabilities have become more advanced as the United States has focused heavily on these areas over the years. Damaged missiles due to a kinetic intercept capability present an opportunity for analysis of the post-damage implications on flight …

Effect Of Freestream Noise On Hypersonic Crossflow-Induced Boundary-Layer Transition, Andrew Bustard, Thomas J. Juliano, Harrison B. Yates, Mark Noftz, Joseph Jewell

Publications

Between the windward and leeward rays, boundary-layer transition on cones at angle of attack in hypersonic flow is dominated by the crossflow instability [1, 2], wherein stationary and/or traveling crossflow vortices develop and can breakdown into turbulence [3]. Stationary crossflow modes are caused by surface roughness or any other steady forcing and produce disturbances that are fixed in place on the surface [3–6]. Stationary vortices create a generalized inflection point in the velocity profile that is inviscidly unstable [7]. This distorted mean flow develops secondary instabilities, whose growth and breakdown is one path to turbulence [8–10]. Traveling crossflow modes are …

On The Implementation And Further Validation Of A Time Domain Boundary Element Method Broadband Impedance Boundary Condition, Fang Q. Hu, Douglas M. Nark

Mathematics & Statistics Faculty Publications

A time domain boundary integral equation with Burton-Miller reformulation is presented for acoustic scattering by surfaces with liners in a uniform mean flow. The Ingard-Myers impedance boundary condition is implemented using a broadband multipole impedance model and converted into time domain differential equations to augment the boundary integral equation. The coupled integral-differential equations are solved numerically by a March-On-in-Time (MOT) scheme. While the Ingard-Myers condition is known to support Kelvin-Helmholtz instability due to its use of a vortex sheet interface between the flow and the liner surface, it is found that by neglecting a second derivative term in the current …

Experiences During The Implementation Of Two Different Project-Based Learning Assignments In A Fluid Mechanics Course., Orlando Ayala, Kristie Gutierrez, Francisco Cima, Julia Noginova, Min Jung Lee, Stacie Ringleb, Pilar Pazos, Krishnanand Kaipa, Jennifer Kidd

Engineering Technology Faculty Publications

There is growing evidence of the effectiveness of project-based learning (PBL) in preparing students to solve complex problems. In PBL implementations in engineering, students are treated as professional engineers facing projects centered around real-world problems, including the complexity and uncertainty that influence such problems. Not only does this help students to analyze and solve an authentic real-world task, promoting critical thinking, but also students learn from each other, learning valuable communication and teamwork skills. Faculty play an important part by assuming non-conventional roles (e.g., client, senior professional engineer, consultant) to help students throughout this instructional and learning approach. Typically in …

Liquid Engine External Pressurizer (Leep), Emily Armbrust

Williams Honors College, Honors Research Projects

The purpose of this project is to take the current liquid rocket engine test stand design and implement an external pressurant instead of utilizing the 2-phase oxidizer vapor to pressurize itself and the fuel. The purpose behind the design is because the team is limited with the current design concerning burn time due to the amount of propellant they can put in the tanks and the pressure it can reach. The initial pressure is currently not held since there is no external input of mass into the tanks, as the propellant is leaving. Adding an external pressurant allow for the …

Schlieren Imaging Of A Supersonic Wind Tunnel, Caleb Townsend, Tayler S. Powell

Williams Honors College, Honors Research Projects

This project exemplifies Schlieren Imaging on a Supersonic Wind Tunnel. Schlieren Imaging allows one to visualize fluid flow by refracting light through a fluid. The Schlieren Imaging system denoted in this paper is used to visualize the shock waves of air onto a test section within a supersonic wind tunnel. This is done by directing a beam of light through a test section and then focusing the light onto a blade edge. This blade edge then breaks up the light beam so that the refractions, created by the pressure differences, are blocked by the knife edge which allows the pressure …

Aerodynamics Wind Tunnel Lab, James Soroczak, Brett Preslar

Williams Honors College, Honors Research Projects

The goal of this project is to create a lab for an aerodynamics class with the purpose of exploring the effects of various physical features and aerodynamic conditions on a wing. The main area of study will be the effects on lift, drag, and moment. To best display these effects, an airfoil/wing to wind tunnel interface with variable physical characteristics will be designed. The various physical alterations will be implemented to show the effect each one has on lift, drag, and moment. These alterations will include different aspect ratios, removable winglets, and various lengths. The airspeed and angle of attack …

Energy Based Diagnostics Of Cfd: Revealing New Insights To Complex Aerodynamics, George Loubimov

Electronic Theses and Dissertations, 2020-2023

This thesis documents a new approach to assess the aerodynamics of complex fluid dynamic systems using modern assessment methods associated with computational fluid dynamics (CFD). The method is developed to extract novel and additional insight in the context of a higher-fidelity modeling tool. Although the methods are based on classical control volume techniques balancing fluid momentum and energy, the approach uses the detailed data provided by CFD to expand on it. Classical methods typically use a fixing control volume defined at simple control surfaces, whereas this assessment method utilizes CFD to provide complex integrals on the control surfaces and uses …

Integrating Experimental Parameter Space For Granular Flow Within Polygon Tumblers, Michaela Mcmahon

Graduate Research Theses & Dissertations

Granular flows are complex phenomena bridging both fluid and solid mechanics and observed frequently in the natural world. The transitional dynamics of acceleration from solid body motion to rapid flow can affect many aspects including volume flow rates and mixing behaviors. In order to study the combination of both variables together within polygon-shaped tumblers, control systems are necessary with a corresponding user interface. This thesis reports an interface for changing variable inputs to the system. Predictions of rotation rates with corresponding interfaces with hardware connections are described. Results of image analysis verify output performance that incorporates the following variable changes: …

Experimental Analysis Of Flowing Layer Characteristics In Equilateral Triangular Tumblers For Quasi-2d Macro-Particle Flow, Jason Quinn Ostenburg

Graduate Research Theses & Dissertations

Rotating tumblers are used in a wide variety of industrial applications from mixing anddeburring to flow regulation and storage. Almost all model tumblers previously analyzed, both theoretically and experimentally, had circular cross sections that produced consistent flowing layer dimensions and steady state flow. In contrast, tumblers with triangular cross sections produced unsteady flow as a direct result of the dynamic dimensions of the flowing surface. Although unsteady, the flow produced in triangular tumblers is periodic every 120◦ of rotation after an initial mixing period. The mechanisms by which the flow characteristics vary as a triangular tumbler rotates and the number …

A Non-Reacting Passive Scalar Comparison Of Starccm And Openfoam In A Supersonic Cavity Flame Holder, Thomas Nuese

Electronic Theses and Dissertations

The scramjet engine equipped with a modern-day airliner would allow for very quick travel across the United States. The major problem is that designing such an engine and testing it to make sure it is safe would cost millions if not billions of dollars. Computational fluid dynamics allows for complex designs to be tested but can still take many days, weeks, or even months to complete. With the use of computational fluid dynamics (CFD), the scramjet engine can be analyzed to determine a quicker way to test and develop a reliable configuration in addition to analyzing the effects of different …

Aerodynamic Performance Of A Biologically Inspired Hybrid Plasma-Mechanical Flow Control And Sensing Device, Joseph Dygert

Graduate Theses, Dissertations, and Problem Reports (ETD)

The continued high global demand for passenger and freight air traffic along with increased use of unmanned aerial vehicles operating in broader Reynolds number regimes has resulted in researchers examining alternative technologies, which would result in safer, more reliable, and superior performing aircraft. Aerodynamic flow control may be one of the most promising approaches to solving this problem, having already proven its ability to enable higher flow efficiency while simultaneously improving overall control of flow behavior such as laminar-to-turbulent transition. Recent research in aerodynamic flow control has seen a pronounced growth in the areas of biomimicry and plasma flow control …

Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan

College of Graduate Studies: Theses & Dissertations

In recent years the development of rocket engines has been mainly focused on improving the engine cycle and creating new fuels. Rocket nozzle design has not been changed since the late 1960s. Recent needs for reliable and reusable rockets, as well as advancements in additive manufacturing, have brought new interest into the aerospike nozzle concept. This nozzle is a type of altitude adjusting nozzle that is up to 90% more efficient than bell nozzles at low altitudes and spends up to 30% less fuel. Since the nozzle body is submerged in the hot exhaust gasses it is difficult to keep …

Numerical Investigation On The Effect Of Spectral Radiative Heat Transfer Within An Ablative Material, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The spectral radiative heat flux could impact the material response. In order to evaluate it, a coupling scheme between KATS - MR and P1 approximation model of radiation transfer equation (RTE) is constructed and used. A Band model is developed that divides the spectral domain into small bands of unequal widths. Two verification studies are conducted: one by comparing the simulation computed by the Band model with pure conduction results and the other by comparing with similar models of RTE. The comparative results from the verification studies indicate that the Band model is computationally efficient and can be used to …

Numerical Simulation Of A Cryogenic Spray, Neel Kishorkumar Shah

Doctoral Dissertations and Master's Theses

Cryogenic sprays have many applications in modern engineering. Cooling of electronic equipment subject to high heat flows, surgical ablation of gastrointestinal mucosae or orbital maneuvering are a few examples of their versatility. However, the atomization of a cryogenic liquid is a complex process. During such an event, aerodynamic effects associated with secondary atomization are further affected by thermodynamic flashing. A better understanding of the characteristics of cryogenic sprays is then necessary to allow for improved design and optimization in applications. The overarching objective of this study is to document such characteristics. The numerical simulation was performed over cryogenic nitrogen spray …

Reduced-Order Dynamic Modeling And Robust Nonlinear Control Of Fluid Flow Velocity Fields, Anu Kossery Jayaprakash, William Mackunis, Vladimir Golubev, Oksana Stalnov

Publications

A robust nonlinear control method is developed for fluid flow velocity tracking, which formally addresses the inherent challenges in practical implementation of closed-loop active flow control systems. A key challenge being addressed here is flow control design to compensate for model parameter variations that can arise from actuator perturbations. The control design is based on a detailed reduced-order model of the actuated flow dynamics, which is rigorously derived to incorporate the inherent time-varying uncertainty in the both the model parameters and the actuator dynamics. To the best of the authors’ knowledge, this is the first robust nonlinear closed-loop active flow …