Engineering Commons^™

Implementing A Linear Quadratic Spacecraft Attitude Control System, Daniel Kolosa

Masters Theses

This thesis implements a linear quadratic attitude control system for a low-thrust spacecraft. The goal is to maintain spacecraft alignment with a time-varying thrust vector needed for trajectory change maneuvers. A linear quadratic attitude control approach is used to maintain spacecraft pointing throughout flight. This attitude control strategy uses the thrust-acceleration input obtained from a linear quadratic optimal trajectory control model that simulates the trajectory of a spacecraft in orbit maneuvers. This attitude model simulates a CubeSat, a small satellite that is equipped with a low-thrust propulsion and attitude control system. An orbit raising and a plane change scenario is …

Optimization Of Titanium Liquid/Gas Diffusion Layers In Proton Exchange Membrane Electrolyzer Cells, Stuart Mccoy Steen

Masters Theses

Polymer electrolyte membrane electrolyzer cells (PEMECs), which are reverse PEM fuel cells (PEMFCs), are effective energy storage medium by producing hydrogen/oxygen from water using electricity from renewable energy sources. This is due in part because of its efficiency, high energy density, compact design, and large capacity. In a PEMEC, a liquid/gas diffusion layer (LGDL) is located between the catalyst layer and the current distributing flow field. The LGDL is expected to transport electrons, heat, and reactants/products to and from the catalyst layer with minimum voltage, current, thermal, interfacial, and fluidic losses. Carbon materials (carbon paper or carbon cloth), typically used …

Characterization Of Convective Heat Transfer Coefficients Of A Self-Aspirated Hot Gas Temperature Probe, Samuel David Stephens

Masters Theses

The objective of this work is to provide a Nusselt Number in a Reynolds Number and Prandtl Number correlation for various surfaces of an aspirated total temperature probe exposed to high temperature flow. The experiment discharged thermally stabilized dry air through large scale models of the probe surfaces in a blow-down wind tunnel and a direct connect facility. The model contained electrically heated sections exposed to the flow which were thermally insulated and instrumented with thermocouples. Experimental data were recorded for several Reynolds numbers and heater positions across three configurations. Uncertainty analysis was performed by the Monte Carlo uncertainty propagation …

Wind Oscillator For Power Genration, Rs Vewen Ramasamy

Masters Theses

This thesis describes in detail the design, mechanical, electrical and software considerations in developing a working model for the non-conventional wind power converter called Wind Oscillator. This was based on the concept developed and patented by Tianshu Liu in the paper “Wind Oscillator and Rotor for Power Generation”[1]. In order to verify the practicality of this idea, a working model of the Wind Oscillator was designed, built and tested in the Western Michigan University wind tunnel facility. LabVIEW data acquisition and photogrammetry was performed on the model so as to evaluate the power generated by the Wind Oscillator and to …

Flight Testing The Piper Pa-32 Saratoga And Pa-31 Navajo, Matthew John Dimaiolo

Masters Theses

The purpose of this thesis was to flight test the University of Tennessee Space Institute’s PA-32 Saratoga and PA-31 Navajo and provide baseline data for future students to reference. Flight tests consisted of both performance and stability and control parameters using a variety of flight test techniques. The tests selected represent the fundamentals that are taught in classes and short courses at the university, beginning with the air data system calibration, proceeding to cruise and climb performance, to stall performance and characteristics, and to static and dynamic stability.

After an introduction and description of the aircraft and flight test program, …

Cfd Analysis Of Viscosity Effects On Turbine Flow Meter Performance And Calibration, Carl Tegtmeier

Masters Theses

In this research turbine flow meters were studied, using computational fluid dynamics (CFD) modeling to the study effects of viscosity on the flow meters, across a wide range of operation, to improve our understanding and their performance. A three-dimensional computational model was created for a typical flow meter geometry. The work began with a steady state model to provide an acceptable initial condition for further simulations. These results were input into a transient model that has a rotating zone around the rotor to provide insight into the interaction between static and rotational structures. In order to automatically adjust the rotor …

Trajectory Analysis And Comparison Of A Linear Aerospike Nozzle To A Conventional Bell Nozzle For Ssto Flight, Elizabeth Lara Lash

Masters Theses

Single-stage to orbit (SSTO) rocket technology offers the potential to substantially reduce launch costs, but has yet to be considered practical for conventional launch vehicles. However, new research in composite propellant tank technology opens the field for renewed evaluation. One technology that increases the efficiency and feasibility of SSTO flight is an altitude compensating rocket engine nozzle, as opposed to a conventional constant area, bell nozzle design. By implementing an altitude compensation nozzle, such as a linear, aerospike nozzle for in-atmosphere flight, the propellant mass fraction (PMF) may be reduced by as much as seven percent compared to a conventional …

Design, Testing, And Calibration Of A Custom Air Data Boom To Obtain Flight Data For The Utsi Cessna-T210j (N33ut), Kristopher Nathaniel Oegema

Masters Theses

Flight testing is dependent on the ability to accurately calculate the flight characteristics of an aircraft during a test. Any error caused by an instrument will grow into potentially larger errors or unacceptable ranges of uncertainty for any flight test calculations. The aircrafts pitot static system is designed to minimize the error in readings caused by the pressure changes resulting in air flying around the aircrafts structure. However, it still does not meet the level of accuracy desired for quality flight testing data. In order to get the most accurate data possible noncommercial equipment is installed on the aircraft for …

Analysis Of Flammability Limits And Gas Properties Of A Solid Rocket Motor Test In A High Altitude Test Facility, Richard Scott Kirkpatrick

Masters Theses

The testing of solid and liquid rocket propulsion systems in a confined test facility often produces explosive or flammable gases which must be safely handled. Often inert gases such as nitrogen are used to lower the molar fraction of oxygen to low enough levels to minimize the probability of an explosion or deflagration. For this thesis, the chemical composition of these rocket exhaust gases mixed with air were used to determine the flammability limits of the gas mixture. Using the ideal gas law and the conservation of mass, the exhaust gas composition and gas properties such as pressure, temperature, volume …

Parameter Determination And Experimental Validation Of A Wire Feed Additive Manufacturing Model, Kannan Suresh Kumar

Masters Theses

“Laser metal deposition is an additive manufacturing method with great scope and robustness. The wire fed additive manufacturing method has great opportunities in space applications and other zero gravity manufacturing processes. Process parameters play an important role in controlling the complex phenomenon and obtaining an ideal manufactured part. These parameters can be efficiently determined using simulation tools which are highly essential in visualizing real world experiments, therefore saving time and experimental costs. The objective of this study is to develop a transient 3D model of laser aided wire feed metal deposition which realizes the heat transfer and fluid flow behavior …

Adjoint-Based Airfoil Shape Optimization In Transonic Flow, Joe-Ray Gramanzini

Masters Theses

"The primary focus of this work is efficient aerodynamic shape optimization in transonic flow. Adjoint-based optimization techniques are employed on airfoil sections and evaluated in terms of computational accuracy as well as efficiency. This study examines two test cases proposed by the AIAA Aerodynamic Design Optimization Discussion Group. The first is a two-dimensional, transonic, inviscid, non-lifting optimization of a Modified-NACA 0012 airfoil. The second is a two-dimensional, transonic, viscous optimization problem using a RAE 2822 airfoil. The FUN3D CFD code of NASA Langley Research Center is used as the ow solver for the gradient-based optimization cases. Two shape parameterization techniques …

Hybrid Manufacturing Process Of SicF/Sic Composite Using Preceramic Polymer, Robert Raymond Meinders

Masters Theses

"Continuous fiber-reinforced silicon carbide (SiC_f/SiC) ceramic composites have been increasingly used due to their high temperature strength and graceful failure mechanisms. A disadvantage is the high cost and lengthy production processes that are required to develop these materials. Polymer infiltration and pyrolysis (PIP) is one of the most attractive fabrication processes for composites due to shape flexibility, mass production and relatively low cost; however, the quality of material obtained by this method has been considered insufficient due to the microstructure defects of the material obtained. This study investigated a hybrid of multiple polymer manufacturing processes to maximize quality …

Space-Based Relative Multitarget Tracking, Keith Allen Legrand

Masters Theses

"Access to space has expanded dramatically over the past decade. The growing popularity of small satellites, specifically cubesats, and the following launch initiatives have resulted in exponentially growing launch numbers into low Earth orbit. This growing congestion in space has punctuated the need for local space monitoring and autonomous satellite inspection. This work describes the development of a framework for monitoring local space and tracking multiple objects concurrently in a satellite's neighborhood. The development of this multitarget tracking systems has produced collateral developments in numerical methods, relative orbital mechanics, and initial relative orbit determination.

This work belongs to a class …

Uncertainty Quantification Of Turbulence Model Closure Coefficients For Transonic Wall-Bounded Flows, John Anthony Schaefer

Masters Theses

"The goal of this work was to quantify the uncertainty and sensitivity of commonly used turbulence models in Reynolds-Averaged Navier-Stokes codes due to uncertainty in the values of closure coefficients for transonic, wall-bounded flows and to rank the contribution of each coefficient to uncertainty in various output flow quantities of interest. Specifically, uncertainty quantification of turbulence model closure coefficients was performed for transonic flow over an axisymmetric bump at zero degrees angle of attack and the RAE 2822 transonic airfoil at a lift coefficient of 0.744. Three turbulence models were considered: the Spalart-Allmaras Model, Wilcox (2006) k-ω Model, and the …

Discrete-Time Neural Network Based State Observer With Neural Network Based Control Formulation For A Class Of Systems With Unmatched Uncertainties, Jason Michael Stumfoll

Masters Theses

"An observer is a dynamic system that estimates the state variables of another system using noisy measurements, either to estimate unmeasurable states, or to improve the accuracy of the state measurements. The Modified State Observer (MSO) is a technique that uses a standard observer structure modified to include a neural network to estimate system states as well as system uncertainty. It has been used in orbit uncertainty estimation and atmospheric reentry uncertainty estimation problems to correctly estimate unmodeled system dynamics. A form of the MSO has been used to control a nonlinear electrohydraulic system with parameter uncertainty using a simplified …