Digital Commons Network^™

Experimental Study On The Effect Of Air Flow On Soap Bubble Formation, John M. Davidson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Soap bubbles are a common interfacial fluid dynamics phenomenon having applications such as buoyant hollow spherical fillers and flow visualization of large scale airflows. In contrast to the dynamics of liquid drops in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented, possibly because soap bubbles have gas-liquid-gas interfaces. Having the thin-liquid-film interface seems to alter the characteristics of the bubble/drop creation process. Thus, the main objective of this study is to experimentally examine how airflow develops and interacts with the soap liquid film as the film stretches and finally collapses to pinch-off. …

Liquid Phase Stability Under An Extreme Temperature Gradient, Zhi Liang, Kiran Sasikumar, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Nonequilibrium Molecular Dynamics Simulations, We Subject Bulk Liquid to a Very High-Temperature Gradient and Observe a Stable Liquid Phase with a Local Temperature Well above the Boiling Point. Also, under This High-Temperature Gradient, the Vapor Phase Exhibits Condensation into a Liquid at a Temperature Higher Than the Saturation Temperature, Indicating that the Observed Liquid Stability is Not Caused by Nucleation Barrier Kinetics. We Show that, Assuming Local Thermal Equilibrium, the Phase Change Can Be Understood from the Thermodynamic Analysis. the Observed Elevation of the Boiling Point is Associated with the Interplay between the "Bulk" Driving Force for the Phase …

Modeling, Simulation, And Characterization Of Space Debris In Low-Earth Orbit, Paul D. Mccall

FIU Electronic Theses and Dissertations

Every space launch increases the overall amount of space debris. Satellites have limited awareness of nearby objects that might pose a collision hazard. Astrometric, radiometric, and thermal models for the study of space debris in low-Earth orbit have been developed. This modeled approach proposes analysis methods that provide increased Local Area Awareness for satellites in low-Earth and geostationary orbit. Local Area Awareness is defined as the ability to detect, characterize, and extract useful information regarding resident space objects as they move through the space environment surrounding a spacecraft.

The study of space debris is of critical importance to all space-faring …

Flying The U-2, Art Saboski

ERAU Prescott Aviation History Program

Learn what it was like to fly the famous U-2, one of history’s most secretive aircraft, from a pilot who has done just that. Art Saboski spent most of his Air Force career flying the U-2; commanding U-2 organizations as well as planning and conducting reconnaissance/intelligence operations. He will give his unique perspectives on the high altitude aircraft, its history, development and current uses today.

Coded Aperture Aided Navigation And Geolocation Systems, Jamie R. Morrison, John F. Raquet, Michael J. Veth

AFIT Patents

A micro air vehicle having a navigation system with a single camera to determine position and attitude of the vehicle using changes the direction to the observed features. The difference between the expected directions to the observed features versus the measured direction to the observed features is used to correct a navigation solution.

Aircraft Tests Arrive At Numbers Pilots Need For Safe Operations, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Flightlines, Vol. 20, No. 2, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Traditional Boat Building: An Intersection Of Zanzibar’S Culture And Environment, Eric Levenson

Independent Study Project (ISP) Collection

This study examined traditional boat building on Uzi Island as a manifestation of Zanzibar’s relationship of environment and culture. Information was gathered about traditional boat building practices, the resource use and management pertaining to boats, the cultural reliance on boats, and local views on environment and conservation. This information showed that the people of Uzi Island were dependent on the use of traditional boats to maintain their livelihood, however the tree types used for boat building are being over-harvested. This tension of culture and environment exposed the need for conservation of Zanzibar’s natural resources in a manner that does not …

Kinetic Simulations Of Plasma Plume Potential In A Vacuum Chamber, Joseph J. Wang, Daoru Frank Han, Yuan Hu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct Simulation Monte Carlo and Particle-in-Cell simulations are carried out to study the potential of a mesothermal plasma plume in a vacuum chamber. The results show that the beam potential with respect to the ambient in a vacuum chamber is different from that in space because the facility plasma can prematurely terminate the plume expansion process. As a result, the plume potential measured in a vacuum chamber may be significantly lower than that under the in-space condition. This can lead to under estimation of the backflow of CEX ions and ionized contaminants in plasma thruster plume modeling.

Tubular And Sector Heat Pipes With Interconnected Branches For Gas Turbine And/Or Compressor Cooling, Brian D. Reding Ii

FIU Electronic Theses and Dissertations

Designing turbines for either aerospace or power production is a daunting task for any heat transfer scientist or engineer. Turbine designers are continuously pursuing better ways to convert the stored chemical energy in the fuel into useful work with maximum efficiency. Based on thermodynamic principles, one way to improve thermal efficiency is to increase the turbine inlet pressure and temperature. Generally, the inlet temperature may exceed the capabilities of standard materials for safe and long-life operation of the turbine. Next generation propulsion systems, whether for new supersonic transport or for improving existing aviation transport, will require more aggressive cooling system …

Adopting A Kinetic Energy Recovery System For Helicopters, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Correlational Study Of Open Circuit Resonant (Sansec) Sensor’S Electric Field Distribution On Lightning Attachment, Kayla M. Farrow, Linda L. Vahala

Electrical & Computer Engineering Faculty Publications

NASA Langley Research Center (LaRC) is conducting research to develop an open circuit SansEC (Sans Electric Connection) sensor to provide lightning strike protection (LSP) in conjunction with damage detection and diagnosis for composite aircraft. SansEC sensors are simplistic devices consisting of an open circuit conductive trace shaped in a planar geometric spiral. The length and width of the conductive trace as well as the gap separation between adjacent turns determines the inductance, resistance and capacitance of the LRC circuit and its associated resonant response. When the sensor is placed on a composite substrate, the electric impedance of the substrate is …

Multi-Stage Axial Compressor With Counter-Rotation, Vinod Gehlot, Magdy S. Attia, Divyam Garg

Publications

A multi-stage axial compressor incorporating a counter-rota­tional movement is provided with a series of rotors mounted along and driven by a driveshaft, and a geared counter-rotat­ing outer casing. A planetary gear system is assembled along a static casing, which can be assembled as a forward or aft casing for the compressor. The bearings of the planetary gear system typically will be aligned concentrically with a center rotor drum assembly mounted along the single driveshaft. The counter-rotating drum assembly will be assembled over the rotor drum assembly and will be engaged by the forward and aft casings so as to provide …

Mechanical Design Of Pird (Principal Investigator Rack Drawer) For Sofia, Hari Prasad Shetty Mr., Murali Krishna Kandlagunta Mrs., John Miles Mr., Zaheer Ali Mr.

STAR Program Research Presentations

SOFIA, the world’s largest airborne observatory with 2.5-meter diameter infrared telescope is equipped with 7 instruments: EXES, FIFI-LS, FLITECAM, FORCAST, GREAT, HAWC, and HIPO. Flying at altitudes between 39,000 and 45,000 feet, SOFIA avoids 99% of the atmospheric water vapor, records and analyzes the infrared radiation from the cosmos. SOFIA is able to observe the occultation of stars by solar system objects. By determining the size, compositions, and atmospheric structures of these objects, SOFIA can help answer the questions on creation and evolution of the universe, formation of the stars and planets, and nature of black hole at the center …

If It Isn’T Tested, It Doesn’T Work: Automated Verification Of Sofia Data Handling Software, Garrett Holthaus, Brett Stroozas, Zaheer Ali

STAR Program Research Presentations

This project involves writing code to automate the verification testing of the Data Handling Working Group (DHWG) software tools for the Stratospheric Observatory for Infrared Astronomy (SOFIA). The DHWG tools extract engineering data from SOFIA missions. Engineering data includes a variety of information on the operations and status of SOFIA systems during a flight, including computer network traffic, user commands, and images acquired from cameras mounted on the telescope assembly. It is important to review engineering data because this data can lead to the discovery of any problems or inefficiencies in SOFIA hardware and software. Analysis of engineering data can …

Interaction Of A Shock Tube Exhaust Flow With A Non-Pre-Mixed Flame, Graham Doig, Zebulan Johnson, Rachel Mann

Aerospace Engineering

No abstract provided.

Experimental Investigation Of Blowing Effects On Turbulent Flow Over A Rough Surface, Mark A. Miller, Alexandre Martin, Sean C. C. Bailey

Mechanical Engineering Faculty Publications

A high Reynolds number turbulent channel flow facility was used to study the combined effects of roughness and flow injection on the mean flow and turbulence characteristics. It was found that the additional momentum injection through the surface enhanced the roughness effects and for the mean flow the effect of blowing was indistinguishable from that of increased roughness. However, for the turbulence statistics, this analogy broke down in that the addition of blowing resulted in behavior which did not follow that predicted by Townsend’s hypothesis. This was observed as a reduction of outer-scaled Reynolds stress well into the outer layer. …

Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin J. Fregly, Jonathan P. Walter, Allison Kinney, Scott A. Banks, Darryl D. D'Lima, Thor F. Besier, David G. Lloyd

Mechanical and Aerospace Engineering Faculty Publications

This study investigates whether use of muscle excitation controls constructed from subjectspecific muscle synergy information can improve optimization prediction of knee contact forces and muscle excitations during walking. Muscle synergies quantify how a large number of experimental muscle electromyographic (EMG) signals can be reconstructed by linearly mixing a much smaller number of neural commands generated by the nervous system. Our hypothesis was that controlling all muscle excitations with a small set of experimentally calculated neural commands would improve prediction of knee contact forces and leg muscle excitations compared to using independently controlled muscle excitations.

T/O Overruns And Veer-Offs On Slippery Runways With Crosswinds, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

More Effective Human Spaceflight Programs And Their International Security Implications, Bert Chapman, Sarag J. Saikia

Libraries Faculty and Staff Scholarship and Research

NASA can more effectively perform its missions by transferring its aeronautic responsibilities to the Federal Aviation Administration and be renamed the National Space Agency. The U.S. must also recognize that space is an emerging arena of international competition and conflict and militarily protect its space assets from China which seeks to use space to restrict the U.S.' ability to defend its strategic interests in regions such as the Western Pacific.

Improving Affordability: Separating Research From Development And From Design In Complex Programs, Bohdan W. Oppenheim

Systems Engineering Faculty Works

This paper presents arguments for why defense programs creating physical systems should clearly separate three developmental phases from each other: research, development and design. Research is to be performed first by small teams of scientists addressing the "unknown unknowns" and maturing fundamental science from TRL of 1 to about 3. Next, development of physical modules is to be performed by small and highly specialized engineers. Finally, the system-level design should focus on efficient trading off the module locations, sizes and shapes versus system performance, mass, power requirements, etc. The design with all modules mature and available is equivalent to a …

Simulations Of Ion Thruster Plume Contamination With A Whole Grid Sputtered Mo Source Model, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A particle simulation based source model is developed to calculate the density distribution of the sputtered Mo atoms for a whole ion optics grid. The source model is used in PIC simulation of ion thruster plume contamination for 3-grid and 2-grid ion thrusters. The results show that the commonly used point-source approximation for sputtered Mo atoms is oversimplified and would lead to over-prediction of contamination deposition.

Creating Exact Bezier Representations Of Cst Shapes, David D. Marshall

Aerospace Engineering

The paper presents a method of expressing CST shapes pioneered by Kulfan into standard Bezier curves and surfaces. Out of the seven standard shape classes identified by Kulfan as representable using CST curves, four of them, including airfoils, can be represented as Bezier curves exactly. For the other three, a convergent series expansion proves insufficient to achieve any practical accuracy, however these three classes are not the most commonly used of the CST classes. With the ability to express most common CST curves and surfaces as generic Bezier curves and surfaces, CST shapes can be used in CAD, solid modeling, …

Coupled Flow Field Simulations Of Charring Ablators With Nonequilibrium Surface Chemistry, Hicham Alkandry, Iain D. Boyd, Alexandre Martin

Mechanical Engineering Faculty Publications

This paper describes the coupling of a Navier-Stokes solver to a material response code to simulate nonequilibrium gas-surface interactions. The Navier-Stokes solver used in this study is LeMANS, which is a three-dimensional computational fluid dynamics code that can simulate hypersonic reacting flows including thermo-chemical nonequilibrium effects. The material response code employed in this study is MOPAR, which uses the one-dimensional control volume nite-element method to model heat conduction and pyrolysis gas behavior. This coupling is demonstrated using a test case based on the Stardust sample return capsule. Coupled simulations are performed at three different trajectory conditions. The effects of the …

A New Approach To Light-Weight Ablators Analysis: From Micro-Tomography Measurements To Statistical Analysis And Modeling, Nagi N. Mansour, Francesco Panerai, Alexandre Martin, Dilworth Y. Parkinson, Alastair A. Macdowell, Abdelmoula Haboub, Timothy A. Sandstrom, Tony Fast, Gerard L. Vignoles, Jean Lachaud

Mechanical Engineering Faculty Publications

The morphology characteristics and ablation behavior of a highly porous carbon fiber preform are studied using a combined experimental/numerical approach. Morphological characterization of the three-dimensional structure of the material is performed by hard X-rays synchrotron micro-tomography at the Advanced Light Source of Lawrence Berkeley National Laboratory. The resulting micro-tomography voxels are used to compute geometrical properties of the carbon preform, like porosity, specific surface area and tortuosity, that are otherwise indirectly measured through experimental techniques. The reconstructed volumes are used to build a computational grid for numerical simulations of the fibers' ablation. By modeling the diffusion of oxygen through the …

Volume Averaged Modeling Of The Oxidation Of Porous Carbon Fiber Material, Alexandre Martin

Mechanical Engineering Faculty Publications

Charring ablators remain the premium choice for space exploration missions that involve atmospheric re-entry. This type of ablative material is composed of a carbon matrix, usually made of fibers, which is then impregnated with a resin. During re-entry, the high heat flux produced by convective heating causes the material to chemically react. First, the resin pyrolyzes, and is vaporized into a gas that travels through the material, and is eventually ejected at the surface. Then, as the temperature rises, the surface of the porous matrix recess through ablative processes. For re-entry conditions typical of space exploration missions, this is mainly …

Flow-Tube Oxidation Experiments On The Carbon Preform Of Pica, Francesco Panerai, Alexandre Martin, Nagi N. Mansour, Steven A. Sepka, Jean Lachaud

Mechanical Engineering Faculty Publications

Oxidation experiments on the carbon preform of a phenolic-impregnated carbon ablator were performed in the NASA Ames ow-tube reactor facility, at temperatures between 700 and 1300 K, under dry air gas at pressures between 103 and 104 Pa. Mass loss, volumetric recession and density changes were measured at different test conditions. An analysis of the diffusion/reaction competition within the porous material, based on the Thiele number, allowed us to identify low temperature and low pressure conditions to be dominated by in-depth volume oxidation. Experiments above 1000 K were found at transition conditions, where diffusion and reaction occur at similar scales. …

Multi-Dimensional Modeling Pyrolysis Gas Flow Inside Charring Ablators, Haoyue Weng, Alexandre Martin

Mechanical Engineering Faculty Publications

Using an ablative thermal/material response code, the importance of three-dimensionality for modeling ablative test-article is addressed. In particular, the simulation of the pyrolysis gas flow inside a porous material is presented, using two different geometries. The effects of allowing the gas to flow out of the side wall are especially highlighted. Results show that the flow inside the test-article is complex, and that the 0D or 1D assumption made in most Material Response (MR) codes might not be valid for certain geometries.

Linear Model Estimation Of Nonlinear Systems Using Least-Squares Algorithm5, Alireza Rahrooh, Walter W. Buchanan, Remzi Seker

Publications

This paper presents utilizes Least-Squares Algorithm to obtain more accurate linear models of nonlinear systems using parameter estimation. This approach generates an optimal linear model which is valid over a wide range of trajectories and converges to the desired steady-state value with no errors unlike the existing techniques. The proposed technique is very efficient and does not require storing the data. Therefore, it can easily be used and implemented with limited resources for undergraduate curriculum especially in underdeveloped countries. Most available techniques for linearization of nonlinear system are only valid about the operating point; furthermore, the knowledge of the operating …

Establishing Mission Requirements Based On Consideration Of Aircraft Operations, Robert A. Mcdonald

Aerospace Engineering

The design requirements for a next-generation commercial aircraft can do much to secure its fate as a success or failure. New aircraft are often designed to meet or surpass the capabilities of an existing aircraft they are intended to replace. However, in the case of unconventional aircraft, this could lead to significant overdesign resulting in nonviable concepts. Instead, a method of analyzing observed aircraft use is presented with the intent of establishing a set of requirements based on replacing aircraft utility instead of capability. Two aircraft in the commercial fleet are used as example cases, and launch customers for each …