Aerospace Engineering Commons^™

Benchmarking Of A Sco2 Heat Exchanger Flow Loop, David Velasco

Doctoral Dissertations and Master's Theses

Heat transfer of supercritical carbon dioxide (sCO2) was studied experimentally by commissioning a sCO2 flow loop featuring a horizontal tube-in-tube counterflow heat exchanger with a circular cross section. The main objective was to establish experimental heat transfer research capabilities for sCO2 at Embry-Riddle Aeronautical University’s (ERAU) Thermal Science Lab. sCO2 experiences a drastic change in thermophysical properties near its critical point that results in unique heat transfer characteristics. The high pressures at which sCO2 exists make the large gradients in thermophysical and transport properties difficult to study, experimentally and numerically. However, understanding the heat transfer characteristics and thermophysical behavior of …

The Influence Of Mixing Duct Length And Phase Of Flight On Wall Temperatures Of A Rocket Based Combined Cycle Engine In Ejector And Air-Augmented Modes, Jonathan Grow

Doctoral Dissertations and Master's Theses

Rocket Based Combined Cycle (RBCC) engines have been theorized as a possible means of powering launch vehicles and high-speed atmospheric vehicles. By incorporating aspects of both air-breathing and rocket propulsion, RBCC engines promise up to a 230 % increase in specific impulse over traditional chemical rocket propulsion by entraining a secondary flow of atmospheric air and mixing it with the exhaust of a rocket motor. Students within the Embry-Riddle Future Space Explorers and Developers Society (ERFSEDS) identified a
problem of excessive heating and structural failure of the mixing duct during launch and transonic flight of a student-built flight test vehicle. …

Modeling, Control, And Hardware Development Of A Thrust-Vector Coaxial Uav, Andrew North

Doctoral Dissertations and Master's Theses

This thesis introduces a unique thrust vector coaxial unmanned aerial vehicle (UAV) configuration and presents a comprehensive investigation encompassing dynamics modeling, hardware design, and controller development. Using the Newton-Euler method, a dynamic model for the UAV is derived to gain in-depth insights into its fundamental flight characteristics. A simple thrust model is formulated and modified by comparing it with data obtained from vehicle testing. The feasibility of manufacturing such a vehicle is assessed through the development of a hardware prototype. Finally, a linear state feedback controller is designed and evaluated using the non-linear dynamics model. The results demonstrate successful validation …

State-Of-The-Art Of Thermal Control Solutions To Establish A Modular, Multi-Orbit Capable Spacecraft Thermal Management System Design Methodology, Robert C. Consolo Jr

Doctoral Dissertations and Master's Theses

Today, the exploration and exploitation of space continues to become a more common occurrence. All types of spacecraft (S/C) utilize various types of thermal management solutions to mitigate the effects of thermal loading from the unforgiving vacuum of space. Without an appropriately designed thermal system, components on-board the S/C can experience failure or malfunction due to fluctuations in temperatures either beyond the designed operational parameters or unstable oscillating temperatures. The purpose of this study is to perform a comprehensive review of technologies available today that are being used for thermal management onboard S/C in addition to investigating the means 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 …

A Comparative Study Between 6 Degree-Of-Freedom Trajectory Model And Modified Point Mass Trajectory Model Of Spinning Projectiles, Ange Du

Doctoral Dissertations and Master's Theses

For spinning projectiles, the 6 Degree-of-Freedom model can closely capture their trajectories with high accuracy and details. However, it comes with the drawbacks of long computation time and needing many aerodynamic coefficients which can be hard to obtain. The Modified Point Mass Trajectory Model was introduced as a simplified solution. This work compares them with each other, and with some more conventional methods. A program is developed to simulate and visualize trajectories. With some augmentations, the Modified Point Mass model is able to generate comparable results in most cases, but not including special cases such as when the projectile is …

7-Dof Robotic Arm Xy-Plane Translational Stability, Christopher Dean Alkire

Doctoral Dissertations and Master's Theses

Robotic arms are traditionally mounted to rigid structures as they perform tasks. As a result, the arm’s movement would not affect the position of its mount and its operational space that it is performing a task within would remain constant. If a robotic arm were to function in orbit, the motion of the arm would cause it to rotate and translate about its center of mass, which changes as the joints of the arm rotate.

The purpose of this thesis is to focus on the two-dimensional translational effects of an arm operating on a simulated zero-friction surface and provide a …

Supersonic Retro-Propulsion Computational Fluid Dynamics Analysis Applied To Future Mars Mission, Margarita Nataly Brandt

Doctoral Dissertations and Master's Theses

Supersonic Retro-Propulsion is one of the most promising emerging technologies being considered by NASA for use in future Mars missions. This new form of Entry Descent Landing has the potential to help increase the allowable payload mass currently constraining many science instruments and operations. Computational Fluid Dynamics was used to show the feasibility of supersonic retro - propulsion in Mars atmospheric conditions. The results presented show the SRP will be able to perform satisfactory using the same conditions that the Curiosity Rover was exposed to during its landing sequence. The plume expansion was analyzed for various cases, moving from free …

Development Of An Exteroceptive Sensor Suite On Unmanned Surface Vessels For Real-Time Classification Of Navigational Markers, Christopher Lloyd Kennedy

Doctoral Dissertations and Master's Theses

This thesis presents the development of an exteroceptive sensor suite for real-time detection and classification of navigational markers on Unmanned Surface Vessels. Three sensors were used to complete this task: a 3D LIDAR and two visible light cameras. First, all LIDAR points were transformed from the sensor’s reference frame to the local frame using a Kalman filter to estimate instantaneous vehicle pose. Next, objects were chosen from the LIDAR data to be classified using either Multivariate Gaussian or Parzen Window Classifiers. Both produce 96% accuracy or better, however, multivariate Gaussian ran considerably faster than the Parzen and was simpler to …

Early Damage State Criterion From A Fault-Seeded Helicopter Gear Using Acoustic Emission And Neural Networks, Rudy L. Baum

Doctoral Dissertations and Master's Theses

In response to five failures since 2008 of the tail gearbox of multiple models of Sikorsky's H-60 helicopter, acoustic emission (AE) data collected from a rotating gearbox test stand at the Naval Air Station in Patuxtent River, MD, was used to monitor the initiation and propagation of a flaw from an electro-discharge machined (EDM) notch seeded on the face of a gear tooth. A period of testing was considered which spanned ~300,000 seconds or ~83 hours and culminates to a damage state such that a flaw has initiated on both ends of the EDM notch. AE data was analyzed for …

Design Optimization Of A Composite Wing Box For High-Altitude Long-Endurance Aircraft, Philip T. Arévalo

Doctoral Dissertations and Master's Theses

A design optimization process is developed to define the wing box structure for High-Altitude Long-Endurance Aircraft (HALE). The goal of this study is to determine the best tradeoff between mass and rigidity of a HALE aircraft wing structure. A preliminary composite laminate structural design procedure is described which uses a NASTRAN-based Finite Element Analysis (FEA), and the Hierarchical Evolutionary Engineering Design System (HEEDS) MDO software to define a locus of acceptable, optimized wing box design definitions.

Mapping Automotive Like Controls To A General Aviation Aircraft, Christopher G. Carvalho

Doctoral Dissertations and Master's Theses

The purpose of this thesis was to develop fly-by-wire control laws enabling a general aviation aircraft to be flown with automotive controls, i.e. a steering wheel and gas/brake pedals. There was a six speed shifter used to change the flight mode of the aircraft. This essentially allows the pilot to have control over different aspects of the flight profile such as climb/descend or cruise. A highway in the sky was used to aid in the navigation since it is not intuitive to people without flight experience how to navigate from the sky or when to climb and descend.

Many believe …

Hydrodynamic Impact Analysis And Testing Of An Unmanned Aerial Vehicle, Isabel Bird

Doctoral Dissertations and Master's Theses

Analysis and testing have been conducted to assess the feasibility of a small UAV that can be landed in the water and recovered for continued use. Water landings may be desirable in a number of situations, for example when testing UAVs outside of the territorial waters of the US to avoid violating FAA regulations. Water landings may also be desirable when conducting surveillance missions in marine environments. Although the goal in landing is to have the UAV lightly set down on the water, rough seas or gusty winds may result in a nose-in landing where the UAV essentially impacts the …

An Investigation To Advance The Technology Readiness Level Of The Centaur Derived On-Orbit Propellant Storage And Transfer System, Nathan L. Silvernail

Doctoral Dissertations and Master's Theses

This research was carried out in collaboration with the United Launch Alliance (ULA), to advance an innovative Centaur-based on-orbit propellant storage and transfer system that takes advantage of rotational settling to simplify Fluid Management (FM), specifically enabling settled fluid transfer between two tanks and settled pressure control. This research consists of two specific objectives: (1) technique and process validation and (2) computational model development. In order to raise the Technology Readiness Level (TRL) of this technology, the corresponding FM techniques and processes must be validated in a series of experimental tests, including: laboratory/ground testing, microgravity flight testing, suborbital flight testing, …

Estimation Of Real-Time Runway Surface Contamination Using Flight Data Recorder Parameters, Donovan C. Curry

Doctoral Dissertations and Master's Theses

Within this research effort, the development of an analytic process for friction coefficient estimation is presented. Under static equilibrium, the sum of forces and moments acting on the aircraft, in the aircraft body coordinate system, while on the ground at any instant is equal to zero. Under this premise the longitudinal, lateral and normal forces due to landing are calculated along with the individual deceleration components existent when an aircraft comes to a rest during ground roll. In order to validate this hypothesis a six degree of freedom aircraft model had to be created and landing tests had to be …

Novel Airframe Design For The Dual-Aircraft Atmospheric Platform Flight Concept, Eric Michael Mckee

Doctoral Dissertations and Master's Theses

A high-altitude, long-endurance unmanned aerial airframe was designed for the innovative Dual-Aircraft Atmospheric Platform flight concept that exploits stratospheric wind velocity gradients to remain aloft indefinitely. Classical aircraft preliminary design techniques and high-fidelity tools were used to establish a baseline configuration.

Performance characteristics of numerous airfoil profiles were evaluated with two-dimensional flow software in an effort to determine the best-candidate airfoil for the unique application. Vortex-Lattice method tools were used to investigate the sensitivity of three-dimensional design parameters upon overall vehicle aerodynamic performance and determine both static and dynamic stability characteristics of the airframe. Performance capabilities of the finalized airframe …