Engineering Commons^™

Development Of Fault Tolerant Adaptive Control Laws For Aerospace Systems, Andres E. Perez Rocha

Doctoral Dissertations and Master's Theses

The main topic of this dissertation is the design, development and implementation of intelligent adaptive control techniques designed to maintain healthy performance of aerospace systems subjected to malfunctions, external parameter changes and/or unmodeled dynamics. The dissertation is focused on the development of novel adaptive control configurations that rely on non-linear functions that appear in the immune system of living organisms as main source of adaptation. One of the main goals of this dissertation is to demonstrate that these novel adaptive control architectures are able to improve overall performance and protect the system while reducing control effort and maintaining adequate operation …

Configuration Validation Of A Novel In-Space Propellant Storage And Transfer System, Priyadarshan Sundararaju

Doctoral Dissertations and Master's Theses

The concept of developing a new technology for on-orbit storage and refueling system has been a great interest among scientists for many decades. This study is about Centaur-based on-orbit propellant storage and transfer. This system takes the advantage of rotational settling to a simple fluid management (FM) system. Specifically, enabling settled fluid transfer and settled pressure control between two tanks. This thesis work focuses on configuration and validation of static and dynamic stability, mass gauging and CFD analysis of the rotational propellant transfer method in space. The application of this technology in Low Earth Orbit (LEO) and Geo-Synchronous Orbit (GEO) …

Effect Of Slot Span On Wing Performance, Juan F. Granizo

Doctoral Dissertations and Master's Theses

This report presents new numerically-derived correlations to estimate the aerodynamic properties of a three-dimensional wing that features a partial to full span fixed slot. Fixed slots have been thoroughly studied in the past with regards to their operation and the relation between slot geometry and wing performance. There have also been many studies on the advantages and disadvantages of tip-slotted wings and the comparison between these and full-slotted wings. Up to this point however, a study on the effects of slot span on wing performance has not been performed. Effect of slot span on wing performance is evaluated in an …

Performance Characterization Of Ceramic Matrix Composites Through Uniaxial Monotonic Tensile Testing, Jóhannes Pétursson

Doctoral Dissertations and Master's Theses

Ceramic matrix composite (CMC) samples were tested in order to characterize their mechanical performance and provide metrics for material process refinement and component design. Monotonic, uniaxial tensile testing of an uncoated carbon fiber reinforced silicon carbide ceramic at room temperature was performed following ASTM standard C1275 to measure ultimate tensile strength and elastic modulus. Equipment verification was carried out through alignment measurement with a gaged tensile specimen using ASTM E1012 to ensure the monotonic nature of the testing equipment. Tensile strength data was treated with Weibull statistical models to produce A and B-basis strength properties for design values.

An alternative …

Turbulence Control In Wall Jets, Jonathan Latim

Doctoral Dissertations and Master's Theses

The turbulent boundary layer has been the focus of many studies over the last century or so due to its engineering significance. Recent studies have shown that the turbulent boundary layer encapsulates extremely energetic large-scale structures which play a much more significant role in its dynamics than has been previously thought. Further, these large scales amplitude and frequency modulate the finer scales of turbulence. This offers a path to control wall turbulence by controlling the large-scales of the flow. The focus of this thesis is to establish ways to manipulate the energy of the large-scale structures in a model turbulent …

Effect Of Flow-Acoustic Resonant Interactions On Aerodynamic Response Of Transitional Airfoils, Joseph Hayden

Doctoral Dissertations and Master's Theses

A high-accuracy numerical study is conducted to examine the impact of flow-acoustic resonant interactions on the aerodynamic response of symmetric and cambered airfoils in the realistic transitional flow regimes with Rec=140,000 and M=0.0465 as well as the low Reynolds number flow regime with Rec=10,000 and M=0.2. The symmetric NACA-0012 and the cambered SD7003 airfoils are investigated at various angles of attack that have been found previously to include both the tone and no-tone producing regimes, with specific focus on the aerodynamic lift response. Additional simulations are conducted with a low-intensity synthetic turbulence introduced upstream of the airfoils in order to …

Model Predictive Control Of A Nonlinear Aeroelastic System Using Volterra Series Representations, Wai Leuk Law

Doctoral Dissertations and Master's Theses

The purpose of this study is to investigate the potential effectiveness of using a Volterra-based Model Predictive Control strategy to control a nonlinear aeroelastic system. Model Predictive Control (MPC), also known as Receding Horizon Control (RHC), entails computing optimal control inputs over a finite time horizon, applying a portion of the computed optimal control sequence, and then repeating the process over the next time horizon. The Volterra series provides input-output models of a dynamical system in terms of a series of integral operators of increasing order, where the first-order Volterra operator models the linear dynamics and the higher-order operators model …

Windshield Defrost And Deice Using Carbon Nanotube Composite, Santhosh Kumar Loganathan

Doctoral Dissertations and Master's Theses

Carbon nanotubes (CNT) are well known for their high thermal and electrical conductivities and can offer a great advantage by converting the applied electrical energy into instant heat with minimum energy loss. The goal of this research is to develop a very thin CNT layer sandwiched between two layers ofglasssubstrate in order to generate instant heat through electrodes. The thin CNT layer is fabricated using the CNTRENETM solution, which is a mixture of single-walled nanotubes (SWNTs) (~75%), double-walled nanotubes (DWNTs), and multi-walled nanotubes (MWNTs) with an average CNT length of ~0.4 - 0.6 μm. The thin layer is deposited by …

Coupled Fluid-Structure Interaction Modeling Of A Parafoil, Brandon Burnett

Doctoral Dissertations and Master's Theses

In the summer of 2014, Performance Designs, Inc. contacted Embry-Riddle Aeronautical University’s Eagle Flight Research Center to lead an investigation on square parachute design and optimization using modern computational methods to reduce costs in experimental testing. This thesis investigates the foundation for using an implicit fluid-structure interaction computational model to tackle the challenges of modeling a highly-flexible, porous fabric for design optimization of a parafoil parachute’s transient performance. Canopy deformations of a single-cell square parafoil using a fluid-structure interaction (FSI) model with nonlinear material modeling is compared to an experimental setup of matching geometry. The results of this thesis yielded …

More Electric Systems Architecture Effect On Business Jet Performance, Kelsey M. Mazur

Doctoral Dissertations and Master's Theses

A more-electric systems architecture, using current state of the art components, is proposed for the business jet Dassault Falcon 2000. A model of the existing aircraft, both of its overall flying characteristics and performance and of its detail systems layout, is created using Pacelab APDc and SysArcc programs. The model is validated with respect to the aircraft published data. Then, another model of the same aircraft is created but, this time, it is for the aircraft with the new architecture and their respective performance is compared. In particular, this results in changes in mission range and the overall system's weight. …

A Detailed Uncertainty Analysis Of Heat Transfer Experiments Using Temperature Sensitive Paint, Anish Prasad

Doctoral Dissertations and Master's Theses

Heat transfer experiments for different cooling techniques for a gas turbine blade are performed and the data are collected via temperature sensitive paint, ammeter, thermocouple and manometer measurement techniques. These data are subjected to uncertainty analysis and the major contributing parameter in the uncertainty is found. A tool to identify the major contributing parameter is devised to reduce the uncertainty in the experiment. Further the effect of temperature difference (surface temperature to bulk temperature) is studied to determine the impact on uncertainty and to determine its importance. The analysis between various implementations of the student’s t distribution are conducted to …

Study Of Surface Tension, Natural Evaporation, And Subcooled Boiling Evaporation Of Aqueous Surfactant Solutions, Matthew John Lehman

Doctoral Dissertations and Master's Theses

The relation between surface tension and surfactant concentration and its effect on solution evaporation under natural convection and subcooled pool boiling is examined through experimental methods. Aqueous solutions of sodium lauryl sulfate (SLS), ECOSURFTM EH-14, and ECOSURFTM SA-9 are used in this study. SLS is an anionic surfactant while EH-14 and SA-9 are environmentally-friendly nonionic surfactants.

Surfactants, surface active agents, are known to affect evaporation performance of solutions and are studied in relation to water loss prevention and heat dissipation. Surfactants could be useful under drought conditions which present challenges to water management on a yearly basis in arid areas …

Automotive-Inspired Inceptors And Control Laws Designed For Simplified Piloted Flight, Kashif Ali

Doctoral Dissertations and Master's Theses

This thesis details the development of a simulator-based experiment in automotive- inspired controls for aircraft. The goal is to fuse the ease of drivability of a car with the flight of an aircraft. A standard automotive control hardware setup coupled with fly-by-wire control laws will allow non-pilots to fly a plane using their familiarity with driving a car. A mathematical description of the control law logic and controller implementation is presented and the human subjects' performance is measured from data collected during experimental testing of the simulator. Preliminary results indicate that non-pilots improve their path-tracking performance and reduce control activity …

Safety Assurance Of Non-Deterministic Flight Controllers In Aircraft Applications, Alfonso Noriega

Doctoral Dissertations and Master's Theses

Loss of control is a serious problem in aviation that primarily affects General Aviation. Technological advancements can help mitigate the problem, but the FAA certification process makes certain solutions economically unfeasible. This investigation presents the design of a generic adaptive autopilot that could potentially lead to a single certification for use in several makes and models of aircraft. The autopilot consists of a conventional controller connected in series with a robust direct adaptive model reference controller. In this architecture, the conventional controller is tuned once to provide outer-loop guidance and navigation to a reference model. The adaptive controller makes unknown …

A Computer Program For The Coupled Implementation Of Meanline And Throughflow Methods To Simplify The Aerodynamic Design Of Multistage Axial Compressors, Alexander V. Rozendaal

Doctoral Dissertations and Master's Theses

A computer program capable of simplifying the preliminary aerodynamic design process of multistage axial compressors has been developed. This interactive design tool, named C-STAAC, combines the Meanline and Throughflow analysis capabilities of two independent compressor design codes to form one standalone system. The program greatly improves the efficiency of the Preliminary-to-Throughflow stages of compressor design by providing fully coupled interaction between the two platforms. The result enables the user to produce stacked airfoil geometry from only a handful of initial input parameters.

The program additionally offers a wide selection of pre- and post-processing capabilities that were not previously available with …

Heat Transfer Analysis Of An Oblique Jet Impingement Cooling On Cmc Rough Surface, Karthik Krishna

Doctoral Dissertations and Master's Theses

A Ceramic Matrix Composite is high strength and high temperature capability composite, utilized in components like heat shield of space vehicles, flame holders and disc brakes. To be used in both static and dynamic components of a future gas turbine engine and even with high temperature capabilities of these CMC components, convection cooling will still likely be required. The surface of the CMC varies significantly from traditional super-alloy used in a modern engine, with large level of roughness and significant three-dimensional waviness. These complex features will impact the behavior of the near wall flows, and affect the heat transfer rates …

Detecting Delamination In Carbon Fiber Composites Using Piezoresistive Nanocomposites, Sandeep Chava

Doctoral Dissertations and Master's Theses

Carbon fiber prepreg composites are utilized successfully as structural materials for different lightweight aerospace applications. Delamination is a critical failure mode in these composite materials. As composite plies separate from each other, the composite loses some of its ability for supporting expected loads. Therefore, detection of delamination at right time is a foremost significance. This study presents a new way for detecting delamination in composite plates using piezoresistive nanocomposites. This new procedure is setup and studied through both experimental and computational investigations. In this research, nanocomposites with 5% coarse graphene platelets are fabricated for detecting delamination. 8-ply carbon fiber prepreg …

The Effect Of Generation On Retention Of Women Engineers In Aerospace And Industry, Kristine Maria Kiernan

Doctoral Dissertations and Master's Theses

The purpose of this dissertation was to determine the nature and extent of differences between generational cohorts regarding the effect of family factors on retention of women in engineering, with an emphasis on women in the aerospace industry. While 6% of the aerospace workforce is made up of aeronautical engineers, an additional 11.2% of the aerospace workforce is drawn from other engineering disciplines. Therefore, the analysis included all engineering sub-disciplines. In order to include women who had left the workforce, women in all industries were used as a proxy for women in aerospace.

Exits to other fields were modeled separately …

Uav As A Service: Providing On-Demand Access And On-The-Fly Retasking Of Multi-Tenant Uavs Using Cloud Services, Justin Yapp

Doctoral Dissertations and Master's Theses

As commercial roles for Unmanned Aerial Vehicles (UAVs) become more well-defined and demand for the services provided by them increases, UAVs rely more on new cloud computing services and co-operative coordination to provide mission planning, control, tracking and data processing. We present UAV as a Service (UAVaaS) framework, which brings features commonly found in traditional cloud services, such as Infrastructure, Platform, and Software as a Service, to the domain of UAVs. Our work aims to conceptualize and design UAVaaS for commercial applications. Specifically, a cloud-provided orchestration framework that allows multi-tenant UAVs to easily serve multiple heterogenous clients at once and …

Computational Investigation Of Impingement Cooling For Regeneratively Cooled Rocket Nozzles, Bianca A. De Angelo

Doctoral Dissertations and Master's Theses

Jet impingement cooling is an internal cooling configuration used in the thermal management of temperature sensitive systems. With rocket engine combustion temperatures rising as high as 3600 K, it is essential for a cooling method to be applied to ensure that the nozzle integrity can be maintained. Therefore, a novel heat transfer study is conducted to investigate if jet impingement cooling is feasible for a regenerative cooling rocket nozzle application. Regenerative cooling for liquid propellant rockets has been widely studied. However, to the best of the author’s knowledge, there is currently no literature describing this method in conjunction with impingement …

Fluidic Jet Turbulence Generators For Deflagration To Detonation Transition In Pulsed Detonation Combustors, Jarrett E. Lowe

Doctoral Dissertations and Master's Theses

The goal of this study is to establish the dominant flow structure required to effectively accelerate the turbulent deflagration flame front to detonation velocity in the shortest possible distance while using a single Jet in Cross Flow (JICF). Jets in crossflow, depending on orientation and momentum ratio, can induce two types of flow structures that propagate downstream; vortex filaments and turbulent eddies. Vortex flow structures are coherent rotating columns that can persist for a considerable distance before diffusing. Turbulent eddies are characterized as random fluctuations in flow velocity or small pockets of rotation. The test rig used for this study …

Study Of Hybrid Magneto-Active Propellant Management Device For Slosh Damping, Leander Paul

Doctoral Dissertations and Master's Theses

Sloshing of liquid upon the application of an external force is a natural phenomenon as the free surface is allowed to move without any constraints. Study of slosh is an ongoing research for many decades and many novel inventions in Propellant Management Devices (PMDs) such as the rigid baffles and elastomeric membranes have been implemented to counteract the free surface effect in both passive and active membrane known as Magneto-Active Propellant Management Device (MAPMD) to actively control the free surface effect and reduce fuel slosh is explored in this research. Being a hybrid membrane, it would initially offer passive resistance …

Analysis Of A Coupled Micro- And Triple-Impingement Cooling Configuration In The C3x Vane, Chase D. Rossman

Doctoral Dissertations and Master's Theses

This study attempts to improve the trailing edge protection of a turbine vane by incorporating two concepts from the literature. These two concepts are optimized near wall cooling passages and a triple-impingement configuration in the vane trailing edge. Finally this study explores a CFD conjugate analysis based on the Shear Stress Transport k(l) turbulence model. The overall goal is to produce a more effective cooling configuration by studying the effects of the flow and heat transfer of the dual configuration, while keeping the integrity of the turbine vane. Star-CCM+ was utilized to carry out the computational data on a 3-D …

Prediction Of Tonal Acoustic Radiation Due To Feedback-Loop Resonant Interactions In Transitional Airfoils, Seyyed Saman Salehian

Doctoral Dissertations and Master's Theses

The objective to this work is to employ the surface integral methods to study the far-field noise propagation from the flow acoustic resonant interactions of the transitional airfoil. The Potential-Theoretic Method (PTM) as an advancement to traditional Kirchhoff methods is presented. The PTM eliminated the need to calculate the normal derivatives of pressure and an arbitrary Kirchhoff surface can be employed. The numerical procedure to implement the PTM is fairly simple. The formulation and physical assumptions of the approach is reviewed, and the numerical procedure is implemented. Furthermore, the two dimensional formulation of the Ffowcs Williams - Hawkings (FW-H) equation …

Safte-Vat Functionality Effects On Flight Instructors' Situation Awareness And Instrument Student Pilots' Performance During Ftd Training, Rafael E. Abreu Vega

Doctoral Dissertations and Master's Theses

SAFTE-VAT is a virtual air traffic control systems that adds the capability to integrate automated air traffic control functionality and generate semiautonomous and autonomous air traffic to the Frasca 172S level 6 plus FTD to improve behavioral fidelity and to facilitate flight instructors the capacity to focus more on instructing student pilots instead of role-playing ATC duties. While SAFTE-VAT may offer a more realistic ATC interaction experience onboard the FTD that may result in a positive transfer of training increase, the effects on flight instructors’ situation awareness and overall student pilot performance are uncertain. In this small study, flight instructors …

An Experimental Study Of Momentum-Driven Unsteady Jets, Sravan Kumar Artham

Doctoral Dissertations and Master's Theses

Jets are seen commonly in nature and engineering and can be broadly classified into steady and unsteady jets. The study of unsteady jets has received little attention when compared to its steady counterpart. A type of unsteady jet is the turbulent puff which is a momentum driven jet in which fluid is ejected from a jet orifice intermittently. Common examples of turbulent puff like jets are coughs and volcanoes. The studies on momentum driven unsteady jets have primarily focused on single ejection events (single puffs) where an instantaneous supply of momentum drives the source fluid downstream of a nozzle. This …

Optical Tracking And Spectral Characterization Of Cubesats For Operational Missions, Forrest Gasdia

Doctoral Dissertations and Master's Theses

Orbital debris in low Earth orbit is of growing concern to operational satellites from the government and commercial sector. With an uptick in worldwide satellite launches and the growing adoption of the CubeSat standard, the number of small objects in orbit are increasing at a faster pace than ever. As a result, a cascading collision event seems inevitable in the near future.

The United States Strategic Command tracks and determines the orbit of resident space objects using a worldwide network of radar and optical sensors. However, in order to better protect space assets, there has been increased interest in not …

The Effect Of Axial Spacing Of Constant And Variable Blockages On The Deflagration-To-Detonation Transition In A Pulse Detonation Engine, Nicole Gagnon

Doctoral Dissertations and Master's Theses

An investigation was conducted into the effects of obstacle spacing on the deflagration-to-detonation transition section length in a pulse detonation engine. Testing was conducted with one hundred and ninety-five different obstacle, and spacing configurations. The configurations included constant, as well as variable spacing between obstacles. The goal of this investigation was to correlate the spacing between obstacles and the blockage ratio of the obstacles with the detonation success and the shortening of the DDT section. The ten cases that achieved the highest percentage of detonations were investigated further to determine the distance needed for the deflagration-to-detonation transition. A 33% blockage …

Investigation Of Pin Fin Cooling Channels For Applications In Gas Turbines, Royce Fernandes

Doctoral Dissertations and Master's Theses

Gas turbine blades are often cooled using internal cooling channels to prevent failure at temperatures beyond material limitations. Pin fin channels are commonly used on the trailing edge of the blades, where they enhance heat transfer and also provide structural support. This study focuses on the validation of several commercially available RANS turbulence models in CFD, that are used to computationally simulate the flow features inside a pin fin cooling channel. Turbulence models investigates are: Menter’s kω SST, realizable k-ε, and a quadratic formulation of the realizable k-ε model. The geometry investigated is a staggered 8 row pin fin channel. …

Mechanical And Electrical Characterization Of Hybrid Carbon Nanotube Sheet-Graphene Nanocomposites For Sensing Applications, Jiukun Li

Doctoral Dissertations and Master's Theses

The unique mechanical and electrical properties of carbon nanotubes and graphitic structures have drawn extensive attention from researchers over the past two decades. The electro-mechanical behavior of these structures and their composites, in which electrical resistance changes when mechanical deformation is applied facilitates their use in sensing applications.

In this work, carbon nanotube sheet- epoxy nanocomposites with the matrix modified with various contents of coarse and fine graphene nanoplatelets are fabricated. The addition of a secondary filler results in improvements of both electrical and mechanical properties. In addition, with the inclusion of the second filler, change in resistivity with mechanical …