Aerospace Engineering Commons^™

Modeling Thin Layers In Material Response Solvers, Christen Setters

Theses and Dissertations--Mechanical Engineering

Thermal Protection Systems (TPS) are a necessary component for atmospheric entry. Most TPS contain thin layers of various materials such as ceramic coatings, pore sealers and bonding agents. When modeling TPS, these thin layers are often neglected due to the difference in scale between the TPS (centimeters) and the thin layers (micrometers). In this study, a volume-averaging flux-conservation method is implemented in the governing equations of a finite volume material response code. The model proposes the addition of a volume and area fraction coefficient which utilizes a weighted-averaging between the amount of thin layer and heat shield material in a …

Turbulence Suppression In An Axially Rotating Pipe, Alyn J. Smith

Theses and Dissertations--Mechanical Engineering

The phenomenon of turbulence suppression in a rotating pipe flow system has been well documented by past research and experimentation. Despite this, the methods that drive this phenomenon have not yet been effectively characterized, especially at higher Reynolds numbers. While many experiments have been performed to better understand swirling turbulent pipe flow, a difficulty that arises is how to test for high levels of rotation without reducing the Reynolds number. This thesis documents the design and construction of a new pressurized pipe flow system at the University of Kentucky aimed at achieving high Reynolds numbers without causing a reduction in …

Electromagnetic Formation Control Using Frequency Multiplexing, Zahra Abbasi

Theses and Dissertations--Mechanical Engineering

This dissertation addresses control of relative positions and orientations of formation flying satellites using magnetic interactions. Electromagnetic formation flight (EMFF) is implemented, in which each satellite is equipped with a set of electromagnetic coils to generate an electromagnetic field. Traditional EMFF technique applies DC magnetic fields which lead to a nonlinear and highly coupled formation dynamics that allow for only position or orientation control of the satellites. We present a new frequency multiplexing method, which is a technique that uses multi-frequency sinusoidal controls, to approximately decouple the formation dynamics and to provide enough controls for both position and orientation control. …

The Kentucky Re-Entry Universal Payload System (Krups): Orbital Flight, James Tyler Nichols

Theses and Dissertations--Mechanical Engineering

Due to the uniqueness of atmospheric entry environments, ground facilities cannot accurately replicate re-entry conditions. Consequently, scientists primarily rely on numerical models to predict these conditions and inform Thermal Protection System (TPS) designs. These models often lack flight validation, which is necessary for increasing their fidelity. Thus, there is a substantial need to obtain such data to advance modeling capabilities.

The Kentucky Re-entry Universal Payload System (KRUPS) is an adaptable test-bed for scientific experimentation with initial application to TPS. This vehicle was designed at the University of Kentucky to serve as an inexpensive means of obtaining validation data to enhance …

Measurements Of Wind Turbine Wake Evolution And Trajectory During Morning Boundary Layer Transition And Under Wake Steering Conditions Via Unmanned Aerial Vehicles, Stewart Nelson

Theses and Dissertations--Mechanical Engineering

In July of 2019, a flight campaign was conducted using semi-autonomous Unmanned Aerial Vehicles (UAVs) at the Port Alma Kruger Energy wind farm in Ontario, Canada, to study various aspects of wind turbine wake evolution. Horizontal transects across the wakes were measured using modified fixed-wing aircraft fitted with a five-hole probe to measure the wind velocity vector. Reference boundary layer conditions were measured by an octocopter with an assortment of mounted sensors flying vertical profiles upstream of the turbines. Three experiments were conducted during the campaign, which consisted of a study on wake behavior during the morning boundary layer transition, …

Attitude Control And Consensus On So(3) Using Sinusoids: Theory And Application To Small Satellites, Roshan Anandrao Chavan

Theses and Dissertations--Mechanical Engineering

We present and analyze kinematic-level and dynamic-level feedback control algorithms for single agent attitude control and multi-agent attitude consensus on SO(3). The kinematic-level algorithms yield attitude feedback controls that are piecewise-continuous sinusoidal angular velocities. The dynamic-level algorithms yield attitude feedback controls that are relative angles of rotational-mass actuators, which are continuous but only piecewise continuously differentiable sinusoids. Furthermore, the dynamic-level algorithms are designed to accommodate actuator stroke constraint. We present application of the dynamic-level control algorithms to attitude control and consensus of small-satellites.

A Computational Fluid-Structure Interaction Method For Simulating Supersonic Parachute Inflation, Jonathan Boustani

Theses and Dissertations--Mechanical Engineering

Following the successful landing of the Curiosity rover on the Martian surface in 2012, NASA/JPL conducted the low-density supersonic decelerator (LDSD) missions to develop large diameter parachutes to land the increasingly heavier payloads being sent to the Martian surface. Unexpectedly, both of the tested parachutes failed far below their design loads. It became clear that there was an inability to model and predict loads that occur during supersonic parachute inflation. In this dissertation, a new computational method that was developed to provide NASA with the capability to simulate supersonic parachute inflation is presented and validated. The method considers the loose …

Structural Optimization Of Space Transit Vehicle Concept, Hercules, James Philip Rogers

Theses and Dissertations--Mechanical Engineering

STRUCTURAL OPTIMIZATION OF SPACE TRANSIT VEHICLE CONCEPT, HERCULES:

A COMPARATIVE STUDY OF STRUCTURAL OPTIONS

Hercules is a vehicle concept developed by NASA Langley's Vehicle Analysis Branch to satisfy the need for sustainable transit between Earth, the moon, and Mars. Hercules features unprecedented abort capabilities and mission flexibility to aid in NASA's Mars campaign. By utilizing modern software to perform structural analysis and optimization for a large selection of stiffened panel concepts, beam concepts, and materials trends in the structural optimization emerge. These trends will be invaluable for the design of future spacecraft needed to fulfill similar roles.

The structural optimization …