Aerospace Engineering Commons^™

Axial Wave Propagation In Truncated Cones, Bhumil A. Diwanji

Mechanical and Aerospace Engineering Theses - Archive

While dealing with problems of impact analysis, where the force is dependent on the time, one can use the transient analysis to compute the response. Transient wave propagation has drawn interest from a long time mainly because of the way structural members behave when subjected to high rates of loading. Solutions to these problems find applications in the design of various mechanical equipments, or any situation where rigid objects are impacting on structural members.The first part of this study deals with the axial wave propagation in cones of different apex angles using transient analysis in ANSYS. The results from the …

Fiber-Optic Pressure Sensor For Time-Of-Flight Measurements In A Shock Wave, Karthikeyan Jagadevan

Mechanical and Aerospace Engineering Theses - Archive

Fiber-optic sensors are widely employed to detect pressures and temperatures precisely. In particular, MEMS-based Ber-optic sensors are immune to electromagnetic interference but may have limitations at high temperatures as encountered in combustors. To ensure high-temperature survivability, such sensors may be bondedanodically. This project explains the development of a Ber-optic pressure sensor utilizing intensity based principle whereby a fused silica optical window was glued to the tungsten carbide enclosure. The development was estimated to determine high pressures of up to at least 3.5 MPa (507 psi). The sensor is designed to capture the pressure pulse and the time-of-flight (TOF) of a …

Peak Stress Of Composite Multiple-Hole Laminates With And Without Patch, Sakthivel Selvaraj

Mechanical and Aerospace Engineering Theses - Archive

In repairing of composite structures, the damage in the composite laminate is usually removed in the form of circular cutouts which results in holes in the laminate. Then a patch laminate is adhesively bonded to the damaged composite laminate. The presence of holes in any structures creates a high stress concentration at the edge of the hole which indeed reduces the life of the structure. The primary objective of this study is to investigate the high stress of the damaged laminate with different hole patterns and the effect of having single and double patches with various configurations on these hole …

Computational Model For Transient And Steady State Analysis Of A 1-Dimensional Auto-Thermal Reformer, Srikanth Honavara Prasad

Mechanical and Aerospace Engineering Theses - Archive

This study presents a 1-dimensional mathematical model of steam reformer to be used with high temperature solid oxide fuel cell (SOFC). Steam reforming (SR) is widely used in industries to produce hydrogen from hydrocarbons. There are various physical processes associated with chemical reactions in the SR of methane such as mass, heat and momentum transport. In this study a one-dimensional SR reactor with built-in preheater and mixing chamber connected to fuel gas and steam reservoirs is modeled and analyzed. The main part of the reformer is a metallic tube with catalyst coating on the inner walls, and it can be …

Compact Survey And Inspection Day/Night Image Sensor Suite For Small Unmanned Aircraft Systems (Eyepod), Alan Bird, Scott A. Anderson, Dale Linne Von Berg, Morgan Davidson, Niel Holt, Melvin Kruer, Michael L. Wilson

Space Dynamics Laboratory Publications

EyePod is a compact survey and inspection day/night imaging sensor suite for small unmanned aircraft systems (UAS). EyePod generates georeferenced image products in real-time from visible near infrared (VNIR) and long wave infrared (LWIR) imaging sensors and was developed under the ONR funded FEATHAR (Fusion, Exploitation, Algorithms, and Targeting for High-Altitude Reconnaissance) program. FEATHAR is being directed and executed by the Naval Research Laboratory (NRL) in conjunction with the Space Dynamics Laboratory (SDL) and FEATHAR’s goal is to develop and test new tactical sensor systems specifically designed for small manned and unmanned platforms (payload weight < 50 lbs). The EyePod suite consists of two VNIR/LWIR (day/night) gimbaled sensors that, combined, provide broad area survey and focused inspection capabilities. Each EyePod sensor pairs an HD visible EO sensor with a LWIR bolometric imager providing precision geo-referenced and fully digital EO/IR NITFS output imagery. The LWIR sensor is mounted to a patent-pending jitter-reduction stage to correct for the high-frequency motion typically found on small aircraft and unmanned systems. Details will be presented on both the wide-area and inspection EyePod sensor systems, their modes of operation, and results from recent flight demonstrations.

Alternative Cooling Technologies For Telecommunication Data Centers: Air Cooling And Rear Door Heat Exchangers, Venkata Naga Poornima Mynampati

Mechanical and Aerospace Engineering Theses - Archive

Telecommunication industry is currently emphasizing to a miniaturization and convergence. The need for smaller, smarter and faster devices is leading drastic increment in power density and accordingly, thermal management of such devices has become a challenge. The heat generated by the devices has to be dissipated in order to ensure proper and efficient functioning of the electronics. Electronics cooling ranges from device level to the room level cooling. Data Center is a facility (room) consisting of servers used for managing and transferring data or information. The thermal management of this facility is challenging due to the huge decrease in floor …

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 …

Laminar-Turbulent Transition For Attached And Separated Flow, Qian Zhang

University of Kentucky Doctoral Dissertations

A major challenge in the design of turbomachinery components for aircraft gas turbine engines is high cycle fatigue failures due to flutter. Of particular concern is the subsonic/transonic stall flutter boundary which occurs at part speed near the stall line. At these operating conditions the incidence angle is large and the relative Mach number is high subsonic or transonic. Viscous effects dominate for high incidence angles.

In order to predict the flutter phenomena, accurate calculation of the steady and unsteady aerodynamic loading on the turbomachinery airfoils is necessary. The development of unsteady aerodynamic models to predict the unsteady forces and …

Pilot Source Study: An Analysis Of Pilot Backgrounds And Subsequent Success In Us Regional Airline Training Programs, Guy M. Smith, David A. Newmyer, Elizabeth Bjerke, Mary Niemczyk, Raymond A. Hamilton

Applied Aviation Sciences - Daytona Beach

The 2010 Pilot Source Study, commissioned to research the success of pilots in initial training for Part 121 operations, analyzed the training performance of 2,156 new-hire pilots in the years 2005-2009. Six regional airlines provided data that was mined from human resource and pilot training files. Five university researchers independently analyzed the data and integrated their results. The study expressed success in terms of fewer extra training events and fewer non-completions in regional airline training. Statistically, the best performing pilots were those who had flight instructor certificates, graduated from collegiate accredited flight programs, received advanced (post-Private) pilot training in college, …

Guidance And Control For Chase Uav Via Sliding Mode Approach, Takeshi Yamasaki, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This study focuses on integrated guidance and control for a chasing UAV against a maneuvering target. a sliding mode approach is selected to develop the integrated guidance and control using a full model of nonlinear, rigid body, 6 Degree-Of-Freedom equations of motion including nonlinear aerodynamics for the target-following capability and maneuverability enhancement against uncertain target maneuvers. Intermediate control variables for the integrated guidance and control system are carefully selected and approximated time derivatives of a sliding surface are applied such that a sliding surface structure is simple and sufficient to propagate the actuator input to the sliding surface in order …

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 …

Integration And Test Of A Refrigerant-Based Cold-Gas Propulsion System For Small Satellites, Ryan Alan Pahl

Masters Theses

"Due to the launch safety constraints placed on university-built small satellites, designing a low-cost propulsion system to meet mission requirements presents a significant challenge to aspiring student engineers. The Missouri University of Science and Technology is currently developing a low-cost, two-phase propulsion system using the refrigerant R-134a as the propellant that can be stored at low pressures while still providing sufficient performance to meet mission goals. The purpose of this study is to present the testing results of a refrigerant-based cold gas system utilizing R-134a as a saturated liquid propellant and the ability to design this system to be portable …

Development Of An Optical Fiber-Based Corrosion Detection Sensor Based On Laser Light Reflection, Manjunatha Shenoy

Mechanical and Aerospace Engineering Theses - Archive

Corrosion plays a detrimental effect on the structural integrity of many engineering structures. It can compromise the safe operation of these structures by forming corrosion pits that deteriorates the structural surfaces and causes stress concentrations. Therefore, it is critical that corrosions are detected before structural integrity is compromised and repair becomes economically prohibitive. However, corrosions usually occur at intricate places that are hard to inspect visually. Manual inspection of the structures for corrosions requires dismantling the structures, which incurs high maintenance costs and could potentially cause damage to the components. One approach to reduce this cost is to detect and …

An Integration Of A Modern Flight Control System Design Technique Into A Conceptual Design Stability And Controls Tool, Aeromech, Amen Omoragbon

Mechanical and Aerospace Engineering Theses - Archive

The aircraft conceptual design (CD) phase is the most abstract, thus challenging phase of the entire aircraft design process. It is the responsibility of the CD engineer to identify and then to explore various aircraft concepts with the goal of arriving at the most promising concept for further evaluation. During this early design phase, the discipline stability and control tends to be underrepresented due to the lack of non-linear aerodynamic and inertia data. The methodology and software AeroMech is a vehicle configuration independent aircraft conceptual design stability and control tool, developed to help the conceptual designer to address stability and …

Imbalance Response Of A Four Degree Of Freedom Rigid Rotor Supported By Hybrid Three Pad Air Foil Bearing, Prajwal Krishna Shetty

Mechanical and Aerospace Engineering Theses - Archive

Air foil bearings (AFB's) are widely used in small to midsized turbomachinery. They provide safer, cleaner and cheaper bearing operation. They are simple in construction, offer very low drag friction and have very high reliability at high speed operations. A major advantage of air foil bearings compared to conventional rigid surface bearings is their superior dynamic performance in rotor bearing systems. Since there is no contact between the rotor and bearing surface, the air foil bearings have a higher service life compared to rigid surface bearings. Hybrid AFB's operate under both hydrodynamic and hydrostatic condition. The present study is a …

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 …

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 …

Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers With Varying Freestream Mach Number, L. (Lian) Duan, I. Beekman, M. P. Mart́In

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, the effects of freestream Mach number on the statistics and large-scale structures in compressible turbulent boundary layers are investigated using direct numerical simulations (DNS). DNS of turbulent boundary layers with nominal freestream Mach number ranging from 3 to 8 are performed. The validity of Morkovin's scaling, strong Reynolds analogy, and Walz's equation are assessed. We find that many of the scaling relations used to express compressible boundary layer statistics in terms of incompressible boundary layers still hold for the range of freestream Mach number considered. Compressibility effects are enhanced with increasing freestream Mach number but remain insignificant, …

Exomedicine Synthesis Paper, Rita Briggs

Robert "Bob" Twiggs STEM Education Collection

A report by Rita Briggs titled "Exomedicine Synthesis Paper" from 2010.

Overnight Atmospheric Transport And Chemical Processing Of Photochemically Aged Houston Urban And Petrochemical Industrial Plume, Rahul A. Zaveri, Paul B. Voss, Carl M. Berkowitz, Edward Fortner, Jun Zheng, Renyi Zhang, Ralph J. Valente, Roger L. Tanner, Daniel Holcomb, Thomas P. Hartley, Leslie Baran

Engineering: Faculty Publications

Overnight atmospheric transport and chemical evolution of photochemically aged Houston urban and petrochemical industrial plume were investigated in July 2005. We report here on the 26 July episode in which the aged plume was tagged 1.5 h before sunset with a pair of free-floating controlled meteorological balloons, which guided quasi-Lagrangian aircraft sampling in the plume as it was advected 300 km to the north over 8 h. The aged plume around sunset was well mixed within a 1600 m residual layer, and was characterized by enhanced levels of aerosol, O3, CO, olefins, acetaldehyde, total odd nitrogen compounds (NOy), and relatively …

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, …

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 …

Measurement Sensitivity In Tapping-Mode Atomic Force Microscopy Using A Bi-Harmonic Drive Signal, Santosh R. Kodandarama, Douglas A. Bristow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In tapping mode atomic force microscopy, surface features are measured indirectly via the amplitude of the tapping cantilever. a change in surface profile is detectable only if it results in an amplitude change that is significant enough to be measured by the optics. Previous works have focused on improving sensitivity through the system's Q-factor, either by changing physical cantilever properties or using feedback control, but those approaches undesirably slow down the dynamic response. in this work we take a novel approach to sensitivity amplification by reshaping the tapping trajectory. by shaping the trajectory so that the probe spends a greater …

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 …

Real-Time On-Board Object Tracking For Cooperative Flight Control, Ajay Kumar Mandava, Emma Regentova, Henry Selvaraj

Electrical & Computer Engineering Faculty Research

One of possible cooperative Situations for flights could be a scenario when the decision on a new path is taken by A Certain fleet member, who is called the leader. The update on the new path is Transmitted to the fleet members via communication That can be noisy. An optical sensor can be used as a back-up for re-estimating the path parameters based on visual information. For A Certain topology, the issue can be solved by continuous tracking of the leader of the fleet in the video sequence and re-adjusting parameters of the flight, accordingly. To solve such a problem …

A Numerical Investigation Of Flowfield Modification In High-Speed Airbreathing Inlets Using Energy Deposition, Matthew Flynn Rohweder

Masters Theses

"Energy deposition in front of dual-mode ram/scramjet engines is numerically investigated utilizing two-dimensional CFD for its potential to modify inlet/isolator flow-fields for engine start/unstart control and for its general potential for generating large-scale flow-field modification in such flows. A simplified (high Mach number) constant-area duct geometry is initially defined in order to test the feasibility of the concept; the results from this initial investigation demonstrates possible beneficial effects of depositing energy upstream of a thermally choked duct in terms of causing massive changes in flow patterns, including the reestablishment of supersonic flow throughout the duct. This study is followed by …

Development Of A Micro-Catbed For Miniature Thrusters, Chance Paul Garcia

Open Access Theses & Dissertations

The goal of this work is to develop a micro catalytic bed for miniature thrusters. A test bed was constructed for experimental testing to characterize several parts of the micro catalytic bed. The reactant fluid studied is 90% Hydrogen Peroxide (H2O2) by weight. Three different cross sectional area designs were tested to determine decomposition efficiency, temperature reaction propensity, optimum flow rate, and temperature distribution across each bed. The products of decomposition were condensed to measure the oxygen released from decomposition. The results will be used to develop the basis for a micro catalytic bed design to implement into future miniature …