Aerospace Engineering Commons^™

An Investigation On Pulsing Performance Of Mn Class Bi-Propellant Thrusters, Carlos Francisco Gomez

Open Access Theses & Dissertations

With the advancement of technology and machining methods, considerable attention has been focused in manufacturing micro thrusters for micro spacecraft applications (Yetter et al, 2003). Micro propulsion systems are currently being investigated for Miniature Kill Vehicles (MKV) and Micro Satellite Systems (MSS) with an emphasis in reducing weight and cost but without affecting performance. Reducing the weight seems practical when reducing the size of the propulsion system, but problems are encountered with system design.

In addition, propulsion requirements strongly influence choice in propellant and complexity. A thorough understanding of stabilizing thrust levels and the ability to control the propulsion system …

Black Carbon Over Mexico: The Effect Of Atmospheric Transport On Mixing State, Mass Absorption Cross-Section, And Bc/Co Ratios, R. Subramanian, G. L. Kok, D. Baumgardner, A. Clarke, Y. Shinozuka, T. L. Campos, C. G. Heizer, B. B. Stephens, B. De Foy, Paul B. Voss, R. A. Zaveri

Engineering: Faculty Publications

A single particle soot photometer (SP2) was operated on the NCAR C-130 during the MIRAGE campaign (part of MILAGRO), sampling black carbon (BC) over Mexico. The highest BC concentrations were measured over Mexico City (sometimes as much as 2μg/m3) and over hillfires to the south of the city. The age of plumes outside of Mexico City was determined using a combination of HYSPLIT trajectories, WRF-FLEXPART modeling and CMET balloon tracks. As expected, older, diluted air masses had lower BC concentrations. A comparison of carbon monoxide (CO) and BC suggests a CO background of around 65 ppbv, and a background-corrected BC/COnet …

Low-Thrust Control Of Orbital Elements, Nathan Harl

Doctoral Dissertations

"This dissertation presents a method for controlling the orbital elements of a spacecraft using continuous low-thrust systems. The method involves the use of a general performance index, which is designed to minimize the difference between the instantaneous orbital elements of a spacecraft and some desired set of orbital elements. Due to the generality of the controller design, the resultant controller can be applied to a wide variety of scenarios about various bodies in space. To minimize the designed performance index, a shooting method and a Sequential Quadratic Programming algorithm are utilized and compared.

The primary application of the general controller …

An Uncertainty Quantification Of The Variation Of Internal Heat Transfer Coefficients And The Effect On Airfoil Life, Jan H. Marsh

Electronic Theses and Dissertations

Uncertainty in accurately knowing applied internal heat transfer coefficients inside of a cooling passage can lead to variability in predicting low cycle fatigue life of a turbine vane or blade. Under-predicting a life value for a turbine part can have disastrous effects on the engine as a whole, and can negate efforts in innovative design for advanced cooling techniques for turbine components. Quantification of this fatigue life uncertainty utilizing a computational framework is the primary objective of this thesis. Through the use of probabilistic design methodologies a process is developed to simulate uncertainties of internal heat transfer coefficient, which are …

Thrust Measurement Of Dielectric Barrier Discharge Plasma Actuators And Power Requirements For Aerodynamic Control, Joseph William Ferry

Masters Theses

"Plasma-based aerodynamic actuators are of interest to researchers because they do not require moving control surfaces or a source of pressurized air to modify a flow field. Dielectric barrier discharge (DBD) plasma actuators have the added advantages of simple installation and low power consumption.

DBD plasma actuators are AC devices. This work measured actuator power consumption and thrust production for driving frequencies between 1 and 18 kHz, and for driving voltages of 6 and 9 kV peak to peak. The actuator consumed between 3 and 22 W of power and produced thrust levels between 0.05 and 0.2 mN per meter …

Thermal Performance Of Cryogenic Multilayer Insulation At Various Layer Spacings, Wesley Louis Johnson

Electronic Theses and Dissertations

Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less than 10-3 torr), and is widely used on spaceflight vehicles. Over the past 50 years, many numerous investigations of MLI have yielded a general understanding of the many variables associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Because conduction between reflectors increases with the thickness of the spacer material, and yet the …

The Gas Team And Nasa (Aka Boil, Boil, Toil And Trouble), Get Away Special Team 2010

Education and Outreach

No abstract provided.

Funboe (Follow-Up Nucleate Boiling On-Flight Experiment), Getaway Special Team 2010

Education and Outreach

No abstract provided.

Quantification Of Uncertainty In Aerodynamic Heating Of A Reentry Vehicle Due To Uncertain Wall And Freestream Conditions, Benjamin R. Bettis

Masters Theses

"The primary focus of this study is to demonstrate an efficient approach for uncertainty quantification of surface heat flux to the spherical non-ablating heatshield of a generic reentry vehicle due to epistemic and aleatory uncertainties that may exist in various parameters used in the numerical solution of hypersonic, viscous, laminar blunt-body flows with thermo-chemical non-equilibrium. Two main uncertainty sources were treated in the computational fluid dynamics (CFD) simulations: (1) aleatory uncertainty in the freestream velocity and (2) epistemic uncertainty in the recombination efficiency for a partially catalytic wall boundary condition. The Second-Order Probability utilizing a stochastic response surface obtained with …

Spacecraft Coating-Induced Charging: A Materials And Modeling Study Of Environmental Extreme, Michelle M. Donegan, Jennifer L. Sample, John R. Dennison, R. Hoffman

All Physics Faculty Publications

As mankind reaches to explore extreme environments in space, the application of ceramics surface coatings is increasing. The 2005 mission concept for Solar Probe used a unique design to achieve the necessary thermal control for a very close approach to the solar corona, including the use of a highly refractory, electrically insulating ceramic coating over a carbon-carbon composite heat shield. The proposed trajectory takes the spacecraft from a Jovian fly-by to within 4 solar radii of the Sun, spanning 5 orders of magnitude in solar radiation and solar wind plasma density as well as spacecraft temperatures from <100 K to >2000 K. Using …

Advancements In Dual-Pump Broadband Cars For Supersonic Combustion Measurements, Sarah Augusta. Tedder

Dissertations, Theses, and Masters Projects

Space- and time-resolved measurements of temperature and species mole fractions of nitrogen, oxygen, and hydrogen were obtained with a dual-pump coherent anti-Stokes Raman spectroscopy (CARS) system in hydrogen-fueled supersonic combustion free jet flows. These measurements were taken to provide time-resolved fluid properties of turbulent supersonic combustion for use in the creation and verification of computational fluid dynamic (CFD) models. CFD models of turbulent supersonic combustion flow currently facilitate the design of air- breathing supersonic combustion ramjet (scramjet) engines. Measurements were made in supersonic axi-symmetric free jets of two scales. First, the measurement system was tested in a laboratory environment using …

Multifunctional Polymer Synthesis And Incorporation Of Gadolinium Compounds And Modified Tungsten Nanoparticles For Improvement Of Radiation Shielding For Use In Outer Space, Emily Grace Harbert

Dissertations, Theses, and Masters Projects

No abstract provided.

Constrained Optimal Orbit Design For Earth Observation, Sharon D. Vtipil

Mechanical & Aerospace Engineering Theses & Dissertations

The purpose of this dissertation is to demonstrate use requirements for a satellite observation mission can be used to determine a constrained optimal orbit based on observation site requirements, observation condition restraints, and sensor characteristics. The typical Earth observation satellite is first designed according to an appropriate orbit; then the observation requirements are used to develop a target schedule. The new design process outlines the development of the appropriate orbit by incorporating user requirements at the forefront of mission planning, not after an orbit has been selected. This research shows how to map the user requirements into constraints for the …

Active Control Of Shocks And Sonic Boom Ground Signal, Bedri Yagiz

Mechanical & Aerospace Engineering Theses & Dissertations

The manipulation of a flow field to obtain a desired change is a much heightened subject. Active flow control has been the subject of the major research areas in fluid mechanics for the past two decades. It offers new solutions for mitigation of shock strength, sonic boom alleviation, drag minimization, reducing blade-vortex interaction noise in helicopters, stall control and the performance maximization of existing designs to meet the increasing requirements of the aircraft industries. Despite the wide variety of the potential applications of active flow control, the majority of studies have been performed at subsonic speeds. The active flow control …

Analysis Of Wake Vortices Of A Medium Range Twin-Propeller Military Cargo Aircraft Using Statistically Designed Experiments, Burhan Sahin

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental study was initiated to analyze the trajectories of the streamwise vortices behind the wing tip and flap of a medium range and propeller driven twin-engine military cargo aircraft. The model used for the experimental study was a generic, high wing and half model of a propeller driven aircraft and mounted within Old Dominion University's Low Speed Wind Tunnel where the wind tunnel flow speed was set to constant value of 9 m/sec. The main purpose of the study was to reach regression models for the motion and vorticity strength of both vortices under varying factors such as angle …

Influence Of Interactions Between Turbulence And Radiation On Transmissivities In Hypersonic Turbulent Boundary Layers, A. M. Feldick, L. (Lian) Duan, M. F. Modest, M. P. Martín, D. A. Levin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In the current paper, a high-fidelity large eddy simulation solver is coupled to our modified line-by-line radiative transport equation solver to study the effects of absorption turbulence-radiation interations in a hypersonic turbulent boundary layer, representative of the Orion CEV entering Earth's atmosphere, at peak heating condition. The turbulent and radiation fields represent extreme conditions typical of Orion, as the simulated boundary layer represents the region of high turbulence coupled to region of highest incident radiation. A simplification in the calculation of molecular spectra with a single temperature property database in allows for tractable calculation of spectral properties. A comparison of …

Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers. Part 2. Effect Of Wall Temperature, L. (Lian) Duan, I. Beekman, M. P. Martín

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we perform direct numerical simulation (DNS) of turbulent boundary layers at Mach 5 with the ratio of wall-to-edge temperature T w/T ℘ from 1.0 to 5.4 (Cases M5T1 to M5T5). The influence of wall cooling on Morkovin's scaling, Walz's equation, the standard and modified strong Reynolds analogies, turbulent kinetic energy budgets, compressibility effects and near-wall coherent structures is assessed. We find that many of the scaling relations used to express adiabatic compressible boundary-layer statistics in terms of incompressible boundary layers also hold for non-adiabatic cases. Compressibility effects are enhanced by wall cooling but remain insignificant, and the …

Direct Detection Of No Produced By High-Temperature Surface-Catalyzed Atom Recombination, Dušan A. Pejaković, Jochen Marschall, Lian Duan, Maria P. Martin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The surface-catalytic recombination of oxygen and nitrogen atoms to form nitric oxide was confirmed by the direct detection of product NO molecules, using single-photon laser-induced fluorescence spectroscopy. Experiments were performed from room temperature to 1200 K in a quartz diffusion-tube sidearm reactor enclosed in a high temperature tube furnace. Atomic nitrogen was generated using a microwave discharge, and atomic oxygen was produced via the rapid gas-phase titration reaction N + NO → O + N2. The use of isotopically labeled titration gases 15N16O and 15N18O allowed for the unambiguous identification of nitric oxide produced by the O + N surface …

Management Of A University Satellite Program With Focus On A Refrigerant-Based Propulsion System, Shawn W. Miller

Masters Theses

"The Missouri University of Science and Technology Satellite (M-SAT) design team has established a satellite program to develop a pair of satellites to perform an autonomous formation flight mission. The resulting configuration was assembled for the Air Force Research Lab University Nanosat Program. This document, written by the Program Manager and former member of the Propulsion subsystem, is a description of the management process used by the team to develop a satellite configuration. Included in the document is a discussion of team organization, techniques for managing a program, and lessons learned during the 2007 to 2008 timeframe. The managing techniques …

Chemical Evolution Of Volatile Organic Compounds In The Outflow Of The Mexico City Metropolitan Area, E. C. Apel, L. K. Emmons, T. Karl, F. Flocke, A. J. Hills, S. Madronich, J. Lee-Taylor, A. Fried, P. Weibring, J. Walega, D. Richter, X. Tie, L. Mauldin, T. Campos, A. Weinheimer, D. Knapp, B. Sive, L. Kleinman, S. Springston, R. Zaveri, J. Ortega, Paul Voss, D. Blake, A. Baker, C. Warneke, D. Welsh-Bon, J. De Gouw, J. Zheng, R. Zhang, J. Rudolph, W. Junkermann, D. D. Riemer

Engineering: Faculty Publications

The volatile organic compound (VOC) distribution in the Mexico City Metropolitan Area (MCMA) and its evolution as it is uplifted and transported out of the MCMA basin was studied during the 2006 MILAGRO/MIRAGE-Mex field campaign. The results show that in the morning hours in the city center, the VOC distribution is dominated by non-methane hydrocarbons (NMHCs) but with a substantial contribution from oxygenated volatile organic compounds (OVOCs), predominantly from primary emissions. Alkanes account for a large part of the NMHC distribution in terms of mixing ratios. In terms of reactivity, NMHCs also dominate overall, especially in the morning hours. However, …