Aerospace Engineering Commons^™

Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, Stephanie Clark

Graduate Theses and Dissertations

Recent advances within the field of cube satellite technology has allowed for the possible development of a maneuver that utilizes a satellite's Low Earth Orbit (LEO) and increased atmospheric density to effectively use lift and drag to implement a noncoplanar orbital maneuver. Noncoplanar maneuvers typically require large quantities of propellant due to the large delta-v that is required. However, similar maneuvers using perturbing forces require little or no propellant to create the delta-v required. This research reported here studied on the effects of lift on orbital changes, those of noncoplanar types in particular, for small satellites without orbital maneuvering thrusters. …

An Inverse Design Method For Supersonic Airfoils, Steven Edward Skare

Master's Theses

Airfoil design is one of the most important aspects of aircraft design. Slight changes in airfoil geometry can lead to significant changes in a wide variety of aircraft performance metrics. Inverse design methods offer an efficient alternative to standard direct methods. The key to this design problem is to derive a direct relationship between changes in airfoil geometry and changes in pressure or velocity distributions. This relationship is then used to modify an initial airfoil and its pressure distribution to match a target pressure distribution, which is specified by design parameters. At this point, the engineer now has a final …

Primary And Secondary Flow Interactions In The Mixing Duct Of A 2-D Planer Air Augmented Rocket, Martin Roy Popish

Master's Theses

Experiments were conducted on the Cal Poly air augmented rocket (AAR) in order to characterize two-dimensional flowfield phenomenon occurring in the mixing duct. The testing utilized a direct connect system where high pressure nitrogen is fed into the combustion chamber, to form a primary flow. The high pressure nitrogen is then expanded through a nozzle, with an area ratio of 22 and an exit area of 0.75 in², up to Mach 4.3. Secondary air is entrained from a plenum chamber which is used to create a lower stagnation pressure for the secondary flow. The two flows mix in …

Novel Heavy Duty Engine Concept For Operation Dual Fuel H 2-Nh3, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A prior paper has presented a novel design of a heavy-duty truck engine fueled with H2. in this design, the customary in-cylinder Diesel injector and glow plug are replaced with a main chamber fuel injector and a jet ignition pre-chamber. the jet ignition pre-chamber is a small volume that is connected to the in-cylinder through calibrated orifices accommodating another fuel injector and a glow or a spark plug that controls the start of combustion. This design permits to operate the engine in four different modes: traditional compression ignition (CI), diffusion, Diesel-like (M1); mixed gasoline/Diesel-like (M2); traditional spark ignition (SI), premixed, …

Reduction Of Solid-Solid Thermal Boundary Resistance By Inserting An Interlayer, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Effective Method is Proposed to Greatly Improve the Thermal Transport Across the Interface between Two Solids with Dissimilar Phonon Spectra. If the Two Solids Have Similar Crystal Structure and Lattice Constant, It is Predicted from the Molecular Dynamics Modeling that an over 50% Reduction of the Thermal Boundary Resistance Can Be Achieved by Inserting a 3-Unit-Cell-Thick Interlayer Whose Debye Temperature is Approximately the Square Root of the Product of the Debye Temperatures of the Two Solids. on the Other Hand, If the Two Solids Have a Large Difference in Lattice Constant, It is Found the Interfacial Atomic Restructuring Plays …

Sun-Synchronous Orbit Slot Architecture Analysis And Development, Eric Watson

Master's Theses

Space debris growth and an influx in space traffic will create a need for increased space traffic management. Due to orbital population density and likely future growth, the implementation of a slot architecture to Sun-synchronous orbit is considered in order to mitigate conjunctions among active satellites. This paper furthers work done in Sun-synchronous orbit slot architecture design and focuses on two main aspects. First, an in-depth relative motion analysis of satellites with respect to their assigned slots is presented. Then, a method for developing a slot architecture from a specific set of user defined inputs is derived.

Heat, Mass And Force Flows In Supersonic Shockwave Interactions, John Michael Dixon

UNLV Theses, Dissertations, Professional Papers, and Capstones

There is no cost effective way to deliver a payload to space and, with rising fuel prices, currently the price to travel commercially is also becoming more prohibitive to the public. During supersonic flight, compressive shock waves form around the craft which could be harnessed to deliver an additional lift on the craft. Using a series of hanging plates below a lifting wing design, the total lift generated can be increased above conventional values, while still maintaining a similar lift-to-drag ratio. Here, we study some of the flows involved in supersonic shockwave interaction. This analysis uses ANSYS Fluent Computational Fluid …

Spacecraft And Propulsion Technician Error, Daniel Clyde Schultz

Doctoral Dissertations and Master's Theses

Commercial aviation and commercial space similarly launch, fly, and land passenger vehicles. Unlike aviation, the U.S. government has not established maintenance policies for commercial space. This study conducted a mixed methods review of 610 U.S. space launches from 1984 through 2011, which included 31 failures. An analysis of the failure causal factors showed that human error accounted for 76% of those failures, which included workmanship error accounting for 29% of the failures. With the imminent future of commercial space travel, the increased potential for the loss of human life demands that changes be made to the standardized procedures, training, and …

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 …

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. …

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 …

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 …

Comm-Multiple Access - Slides, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Comm-Multiple Access" from April 24, 2012.

Ec 723 Satellite Communication Systems, Mohammed Khedr

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Mohammed Khdr titled "EC 723 Satellite Communication Systems" from April 10, 2012.

Space Science And Astrophysics Programs, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Space Science and Astrophysics Programs" from April 9, 2012.

Asteroid Retrieval Feasibility Study, John Brophy, Fred Culick, Louis Friedman, Pedro Llanos, Et Al.

Publications

This report describes the results of a study sponsored by the Keck Institute for Space Studies (KISS) to investigate the feasibility of identifying, robotically capturing, and returning an entire Near-Earth Asteroid (NEA) to the vicinity of the Earth by the middle of the next decade. The KISS study was performed by people from Ames Research Center, Glenn Research Center, Goddard Space Flight Center, Jet Propulsion Laboratory, Johnson Space Center, Langley Research Center, the California Institute of Technology, Carnegie Mellon, Harvard University, the Naval Postgraduate School, University of California at Los Angeles, University of California at Santa Cruz, University of Southern …

Aerodynamics Of An Aerofoil In Transonic Ground Effect: Numerical Study At Full-Scale Reynolds Numbers, G. Doig, T. J. Barber, A. J. Neely, D. D. Myre

Aerospace Engineering

The potential positive effects of ground proximity on the aerodynamic performance of a wing or aerofoil have long been established, but at transonic speeds the formation of shock waves between the body and the ground plane would have significant consequences. A numerical study of the aerodynamics of an RAE2822 aerofoil section in ground effect flight was conducted at freestream Mach numbers from 0·5 to 0·9, at a range of ground clearances and angles of incidence. It was found that in general the aerofoil's lifting capability was still improved with decreasing ground clearance up until the point at which a lower …

Section Abstracts: Aeronautical And Aerospace Sciences

Virginia Journal of Science

Abstracts of the Aeronautical and Aerospace Sciences Section for the 90th Annual Meeting of the Virginia Academy of Science, May 23-25, 2015. Norfolk State University, Norfolk, Virginia.

A Nanoporous Silicon Nitride Membrane Using A Two-Step Lift-Off Pattern Transfer With Thermal Nanoimprint Lithography, Bhargav P. Nabar, Zeynep Çelik-Butler, Brian H. Dennis, Richard E. Billo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nanoimprint lithography is emerging as a viable contender for fabrication of large-scale arrays of 5500 nm features. A fabrication process for the realization of thin nanoporous membranes using thermal nanoimprint lithography is presented. Suspended silicon nitride membranes were fabricated by low-pressure chemical vapor deposition (LPCVD) in conjunction with a potassium hydroxide-based bulk micromachining process. Nanoscale features were imprinted into a commercially available thermoplastic polymer resist using a prefabricated silicon mold. The pattern was reversed and transferred to a thin aluminum oxide layer by means of a novel two-stage lift-off technique. The patterned aluminum oxide was used as an etch mask …