Engineering Commons^™

Closed-Loop Thrust And Pressure Profile Throttling Of A Nitrous Oxide/Hydroxyl-Terminated Polybutadiene Hybrid Rocket Motor, Zachary W. Peterson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Hybrid motors that employ non-toxic, non-explosive components with a liquid oxidizer and a solid hydrocarbon fuel grain have inherently safe operating characteristics. The inherent safety of hybrid rocket motors offers the potential to greatly reduce overall operating costs. Another key advantage of hybrid rocket motors is the potential for in-flight shutdown, restart, and throttle by controlling the pressure drop between the oxidizer tank and the injector. This research designed, developed, and ground tested a closed-loop throttle controller for a hybrid rocket motor using nitrous oxide and hydroxyl-terminated polybutadiene as propellants. The research simultaneously developed closed-loop throttle algorithms and lab scale …

Design Of A Split Hopkinson Bar Apparatus For Use With Fiber Reinforced Composite Materials, Shawn Michael Lang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tabulated material properties are the starting block for the design of most structures. Mechanical structures undergo a wide range of loading conditions. Structures can be loaded statically or dynamically with a wide range of strain rates. With impact loading or high strain rates the relationships between stress and strain are not the same as in static loading. It has been observed that material properties are dependent upon the rate at which they are tested. Many investigators have studied the effect of high compressive strain rate loading conditions, in metals. The most common method for determining the dynamic response of materials …

Numerical And Experimental Study Of Anisotropic Effective Thermal Conductivity Of Particle Beds Under Uniaxial Compression, Jingwen Mo

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Planetary heat flow is of great interests to planetary scientists, which can be used to determine the history and current status of pianetary bodies. Thermal conductivities of planetary bodies are generally measured using long needle-like probes inserted into planet's surface, which measure the horizontal effective thermal conductivity (parallel to the planetary surface). The vertical effective thermal conductivity (perpendicular to the planetary surface), used for heat flow calculation, is assumed to be the same as the horizontal effective thermal conductivity. However, ETC of particle beds is known to be an anisotropic property under low compressive pressures.

The objective of this study …

Experimental Studies Of Vertical Mixing In An Open Channel Raceway For Algae Biofuel Production, Ram Sudheer Voleti

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The USU BioEnergy Center has been successful in developing algae feedstocks for renewable biofuels and bioproducts. The concept is to utilize and maximize algae feedstocks for liquid transportation fuels, biomass for burning and digestion, and high value co-products. It is theorized that increasing the mixing in open and closed algal production systems improves the productivity of the algae culture. A raceway cultivation system was chosen to examine the phenomena of mixing. Vertical mixing will provide more uniform exposure to sunlight for all of the algae in the raceway. The main focus of this research was to increase vertical mixing. Delta …

Waste Heat Utilization In An Anaerobic Digestion System, Brett Boissevain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Anaerobic digestion has great potential as an energy source. Not only does it provide an effective method for waste mitigation, but it has the potential to generate significant quantities of fuel and electricity. In order to ensure efficient digestion and biomass utilization, however, the system must be continuously maintained at elevated temperatures. It is technically feasible to supplement such a system with outside energy, but it is more cost effective to heat the system using only the produced biogas. While there is considerable literature covering the theory of anaerobic digestion, there are very few practical studies to show how heat …

Evaluation Of Turbulence Variable Distributions For Incompressible Fully Rough Pipe Flows, Emilie B. Fowler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The specific turbulent kinetic energy, root-mean-square fluctuating vorticity, and mean-vortexwavelength distributions are presented for fully rough pipe flow. The distributions of these turbulence variables are obtained from a proposed turbulence model. Many of the turbulence models commonly used for computational fluid dynamics are based on an analogy between molecular and turbulent transport. However, traditional k-ε and k-ω models fail to exhibit proper dependence on the molecular viscosity. Based on a rigorous application of the Boussinesq’s hypothesis, Phillips proposed a vorticity-based transport equation for the turbulent kinetic energy. The foundation for this vorticity-based transport equation is presented. In future development of …

An Investigation Into Delta Wing Vortex Generators As A Means Of Increasing Algae Biofuel Raceway Vertical Mixing Including An Analysis Of The Resulting Turbulence Characteristics, Aaron H. Godfrey

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Current standards of living and future prosperity are closely tied to the availability of sufficient and inexpensive energy resources. Currently society is fueled primarily by some form of fossil fuel. By their very nature these fuel sources are non-renewable, thus our current energy habits are unsustainable. Among the various renewable energy technologies is the capability to produce diesel fuel by colonies of algae. While this technology has many positive features it remains too expensive to be a realistic fuel source. The current work performed analysis using computer simulation of an aquatic environment commonly used to grow algae for the purposes …

Effective Thermal Conductivity Of Tri-Isotropic (Triso) Fuel Compacts, Charles P. Folsom

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Next Generation Nuclear Plant (NGNP) program objective is to develop a new type of nuclear reactor that produces process heat instead of electricity. The process heat can be used in the production of hydrogen and many other industrial processes. As part of the NGNP program a new type of nuclear fuel is being developed. The fuel is a composite construction of specially coated fuel particles and graphite pressed together in a cylindrical compact.

Thermal conductivity is an important thermophysical property of the fuel that needs to be measured. Knowledge of the thermal conductivity of the fuel will provide accurate …

Statistical Methods For Launch Vehicle Guidance, Navigation, And Control (Gn&C) System Design And Analysis, Michael Benjamin Rose

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A new tool for launch vehicle design and analysis is developed. The tool is capable of rapid analysis of requirements tradeoffs affecting system design and developed to reduce turnaround time for launch vehicle design and mission planning. It is streamlined to quickly determine trajectory and attitude control dispersions which represent how far the actual trajectory is expected to deviate from the nominal flight path, propellant dispersions which represent how much propellant is required to meet mission requirements, and navigation errors which represent how far the navigation filter’s estimate of the actual trajectory is expected to deviate from the actual trajectory. …

Spacecraft Collision Probability Estimation For Rendezvous And Proximity Operations, Michael R. Phillips

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An increasing number of missions require spacecraft to fly in close proximity. Despite the technological advances that have made these types of missions increasingly possible there remains a limit to how accurately the trajectory of a spacecraft can be predicted. As such, one of the main risks to spacecraft in close proximity is the threat of a collision. Many methods exist for computing the probability of collision between spacecraft. These methods incorporate the uncertainty in predicting the spacecrafts motion when computing an estimate. The accuracy and required computation time of these methods very greatly. A poor estimate of collision risk …