Aerospace Engineering Commons^™

Loss Enhanced Transmission And Collimation In Anisotropic Epsilon-Near-Zero Metamaterials, L. Sun, S. Feng, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We verify the extraordinary transmission enhancement and collimation induced by the material loss in anisotropic epsilon-near-zero metamaterials, and reveal the physical mechanism of this exotic electromagnetic phenomenon via the iso-frequency contour analysis. In addition, we demonstrate the possibility in realization of such loss enhanced transmission of Gaussian beam in realistic silver-germanium multilayered structures by applying full-wave numerical simulations.

Flightlines, Vol. 19, No. 2, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Strain Rate And Orientation Dependencies Of The Strength Of Single Crystalline Copper Under Compression, Virginie Dupont, Timothy C. Germann

Aerospace Engineering - Daytona Beach

Molecular dynamics (MD) simulations are used to model the compression under uniaxial strain of copper single crystals of different orientations at various temperatures and strain rates. Uniaxial strain is used because of the close resemblance of the resulting stress state with the one behind a shock front, while allowing a control of parameters such as strain rate and temperature to better understand the behavior under complex dynamic shock conditions. Our simulations show that for most orientations, the yield strength of the sample is increased with increasing strain rate. This yield strength is also dependent on the orientation of the sample, …

Fundamental Sizing Implications Of Constant Or Increasing Weight Aircraft, Robert A. Mcdonald

Aerospace Engineering

As the energy storage capabilities of batteries and fuel cells advance, these technologies are increasingly being considered for aircraft primary propulsion. In addition to other fundamental differences from conventional systems, these concepts may have constant or even increasing mass throughout the mission. In this paper, the implications of constant or increasing mass on aircraft sizing are considered with the aim of generating insight for the design of these systems.

A (Declassified) History Of Military Drones, Stephen Rayleigh

ERAU Prescott Aviation History Program

Unmanned Aerial Vehicles or drones, are said to be the newest technology of contemporary warfare, but the military's use of drones spans the last 100 years. Hear the riveting story of the numerous secret UAV programs around the world, starting with the Sperry Aerial Torpedo Project in 1918 (consulted by Orville Wright), the German cruise missile program, American remote controlled bombers in WWII, the Firebee recon drone used in Vietnam, Israel's highly successful UAV program, and finally the coming of age of UAV's in Operation Desert Storm.

Jet Engine Thrust Ratings, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

A Method To Generate Pressure Gradients For Molecular Simulation Of Pressure-Driven Flows In Nanochannels, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

One of the Difficulties in Molecular Simulation of Pressure-Driven Fluid Flow in Nanochannels is to Find an Appropriate Pressure Control Method. When Periodic Boundary Conditions (PBCs) Are Applied, a Gravity-Like Field Has Been Widely Used to Replace Actual Pressure Gradients. the Gravity-Fed Method is Not Only Artificial, But Not Adequate for Studying Properties of Fluid Systems Which Are Essentially Inhomogeneous in the Flow Direction. in This Paper, a Method is Proposed Which Can Generate Any Desired Pressure Difference to Drive the Fluid Flow by Attaching a "Pump" to the Nanofluidic System, While the Model is Still Compatible with PBCs. the …

Telescope Assembly Alignment Simulator Performance Optimization, Joshua G. Thompson, Brian Eney, Zaheer Ali, Bob Thompson

STAR Program Research Presentations

The Telescope Assembly Alignment Simulator (TAAS) calibrates scientific instruments (SI’s) that are installed on the Stratospheric Observatory For Infrared Astronomy (SOFIA). An SI’s accuracy is directly dependent on the consistent performance of the TAAS, which has never been fully characterized. After designing various thermal and optical experiments to identify the current unknowns of TAAS, we now have a far better grasp on how the equipment behaves.

Potential Significance Of Photoexcited No2 On Global Air Quality With The Nmmb/Bsc Chemical Transport Model, O. Jorba, D. Dabdub, Christopher S. Blaszczak-Boxe, C. Pérez, Z. Janjic, J. M. Baldasano, M. Spada, A. Badia, M. Gonçalves

Publications and Research

Atmospheric chemists have recently focused on the relevance of the NO2* + H2O → OH + HONO reaction to local air quality. This chemistry has been considered not relevant for the troposphere from known reaction rates until nowadays. New experiments suggested a rate constant of 1.7 × 10−13 cm3 molecule−1 s−1, which is an order of magnitude faster than the previously estimated upper limit of 1.2 × 10−14 cm3 molecule−1 s−1, determined by Crowley and Carl (1997). Using the new global model, NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM), simulations are presented that assess the potential significance of this chemistry on global …

Merrill-Cazier Library Gas Exhibition, Betty Rozum, Andrew Wesolek, Pamela N. Martin

Education and Outreach

This exhibition, presented in the Merrill-Cazier Library, captured the history and accomplishments of the GAS program. Click the download button to see a PowerPoint presentation featuring images and text from the exhibition.

Extended Pcr Rules For Dynamic Frames, Florentin Smarandache, Jean Dezert

Branch Mathematics and Statistics Faculty and Staff Publications

In most of classical fusion problems modeled from belief functions, the frame of discernment is considered as static. This means that the set of elements in the frame and the underlying integrity constraints of the frame are fixed forever and they do not change with time. In some applications, like in target tracking for example, the use of such invariant frame is not very appropriate because it can truly change with time. So it is necessary to adapt the Proportional Conflict Redistribution fusion rules (PCR5 and PCR6) for working with dynamical frames. In this paper, we propose an extension of …

The Synergistic Integration Of Computational Fluid Dynamics And Experimental Fluid Dynamics For Ground Effect Aerodynamics Studies, Tj Barber, G Doig, C Beves, I Watson, S Diasinos

Aerospace Engineering

This article highlights the ‘synergistic’ use of experimental fluid dynamics (EFD) and computational fluid dynamics (CFD), where the two sets of simulations are performed concurrently and by the same researcher. In particular, examples from the area of ground effect aerodynamics are discussed, where the major facility used was also designed through a combination of CFD and EFD. Three examples are than outlined, to demonstrate the insight that can be obtained from the integration of CFD and EFD studies. The case studies are the study of dimple flow (to enhance aerodynamic performance), the analysis of a Formula-style front wing and wheel, …

Aerodynamics Of An Aerofoil In Transonic Ground Effect: Methods For Blowdown Wind Tunnel Scale Testing, G. Doig, T. J. Barber, A. J. Neely, D. D. Myre

Aerospace Engineering

No abstract provided.

Multi-Dimensional Modeling Of Charring Ablators, Haoyue Weng, Huaibao Zhang, Ovais U. Khan, Alexandre Martin

Mechanical Engineering Faculty Publications

Re-entry of a spacecraft occurs at the hypersonic regime where the flow field is extremely complex: high temperature gradients occurring in the shock-layer region ionize and dissociate the air. Even if a large portion of heat generated during this process is convected away in the surrounding air, a fraction of it is still transferred to the vehicle. Therefore, it is important to protect the vehicle with a suitable kind of shielding. Of the many techniques available today, use of ablative material is gaining popularity. The basic idea behind an ablating heat shield is that the energy incident on the spacecraft …

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 …

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 …

Flightlines, Vol. 19, No. 1, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Peridynamic Model For Dynamic Fracture In Unidirectional Fiber-Reinforced Composites, Wenke Hu, Youn Doh Ha, Florin Bobaru

Department of Mechanical and Materials Engineering: Faculty Publications

We propose a computational method for a homogenized peridynamics description of fiber-reinforced composites and we use it to simulate dynamic brittle fracture and damage in these materials. With this model we analyze the dynamic effects induced by different types of dynamic loading on the fracture and damage behavior of unidirectional fiber-reinforced composites. In contrast to the results expected from quasi-static loading, the simulations show that dynamic conditions can lead to co-existence of and transitions between fracture modes; matrix shattering can happen before a splitting crack propagates. We observe matrix–fiber splitting fracture, matrix cracking, and crack migration in the matrix, including …

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 …

Engineering Innovation And Design For Stem Teachers And The Stem Quality Framework, James Rowley, Sandi Preiss, Margaret Pinnell, Suzanne Franco

Mechanical and Aerospace Engineering Faculty Publications

The backbone of economic growth in the United States relies on engineering innovation. However, engineering innovation cannot occur without engineers and scientists. Unfortunately however, many K-12 students do not have a good understanding of the engineering design process or the vast field of engineering. As a result, many students lose interest in math and science and do not pursue Science, Technology, Engineering and Math (STEM) fields. This paper will describe a unique partnership among the Teacher Education Program and School of Engineering at the University of Dayton (UD) and the Dayton Regional STEM Center (DRSC). This partnership initiated with the …

Simulation Of Blood Flow And Nanoparticle Transport In A Stenosed Carotid Bifurcation And Pseudo-Arteriole, Graham Doig, Guan H. Yeoh, Victoria Timchenko, Gary Rosengarten, Tracie J. Barber, Sherman C.P. Cheung

Aerospace Engineering

Numerical simulation of flow through a realistic bifurcated carotid artery geometry with a stenosis has been conducted for comparison to experimental measurements. The behaviour of simplified therapeutic nanoparticles in relatively low concentration was observed using a discrete particle approach. The role of size (diameters from 500 nm to 50 nm) in determining particle residence time and the potential for both desirable and undesirable wall interactions was investigated. It was found that mean particle residence time reduced with decreasing particle diameter, and the percentage of particles experiencing one or more wall interactions increased simultaneously. Further simulations were conducted on a scaled-down …

Fadec Advances Allow Better Engine Performance, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Ablation Test-Case Series #2. Numerical Simulation Of Ablative-Material Response: Code And Model Comparisons, Jean R. Lachaud, Alexandre Martin, Tom Van Eekelen, Ioana Cozmuta

Mechanical Engineering Faculty Publications

This test-case series on the numerical simulation of the response of ablative-materials really started out of pure curiosity. Code developers and users were curious to see "how the codes compare" and "what is the effect of the different hypotheses in the models implemented". The objective of these test-case series is to propose problems of increasing complexity until it is agreed that the most-elaborated well-defined problem is formulated. The first test-case was mostly a simple heat transfer problem chosen for it’s simplicity (it is summarized in section 2.1). The second test-case series goes one step further, with the objective of reaching …

Ablation Test-Case Series #3. Numerical Simulation Of Ablative-Material Response: Code And Model Comparisons, Tom Van Eekelen, Jean R. Lachaud, Alexandre Martin, Ioana Cozmuta

Mechanical Engineering Faculty Publications

The test-case series #3 will be a further extension of the tests defined within the framework of the NASA ablation modelling workshops. In order to reduce the amount of work, all tests within test-case series #3, will use the TACOT material defined by Lachaud et al. The main goal of this new series, is to test the 3D modelling capabilities of the participating codes. The first 1D results were presented at the 4th Ablation workshop, and together with the results of the second test-case series, will be discussed and analyzed more thoroughly at the 5th Ablation Workshop, Feb. 28- March …

Study Of Turbulence-Radiation Interaction In Hypersonic Turbulent Boundary Layers, L. (Lian) Duan, M. P. Martín, A. M. Feldick, M. F. Modest, D. A. Levin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations are conducted to investigate the effect of turbulence-radiation interaction in hypersonic turbulent boundary layers, representative of the Orion crew exploration vehicle at the peak heating condition during reentry. Both the effects of emission and absorption are considered by solving the radiative transfer equation using the tangent slab approximation and a spectral model with line-by-line accuracy. Nondimensional governing parameters to measure the significance of turbulence-radiation interaction are proposed, and the direct numerical simulation fields with and without radiation coupling are used to assess turbulence-radiation interaction. Is it found that the fluid medium within the boundary layer is optically …

Generation Of Four Dimensional Grid Of Probabilistic Hazards For Use By Decision Support Tools, Ian A. Wilson

Publications

A new method and system for generating probabilities of objective values of hazards as a fine granularity grid in four dimensions (three spatial dimensions plus time) to be used by decision support and visualization tools. Utilizing the pro­posed system, proxies for hazard data received at different times and in different formats may be used as input data to a grid of intelligent software agents which generate a four dimensional matrix of probabilities of objective values of hazards. The method allows for proxies and/or subjective information on hazards that may arrive asynchronously and with coarse temporal and spatial accuracy to be …

Aircraft Operations Based Mission Requirements, Robert A. Mcdonald

Aerospace Engineering

The mission capabilities of aircraft in the current commercial fleet are a combined result of many factors. The launch customer for each aircraft has a voice in determining the requirements. The manufacturer desires to best position the aircraft in the market considering their own aircraft and their competitors aircraft it will replace and compete with. Consequently, anyone considering the development of an aircraft to compete with or replace an aircraft in-service must do more than simply choose to meet the capabilities of that aircraft. This is especially true when unconventional systems are considered; the fundamental trade-offs for these systems may …

High Speed Flow Simulation In Fuel Injector Nozzles, Sukanta Rakshit

Masters Theses 1911 - February 2014

Atomization of fuel is essential in controlling combustion inside a direct injection engine. Controlling combustion helps in reducing emissions and boosting efficiency. Cavitation is one of the factors that significantly affect the nature of spray in a combustion chamber. Typical fuel injector nozzles are small and operate at a very high pressure, which limit the study of internal nozzle behavior. The time and length scales further limit the experimental study of a fuel injector nozzle. Simulating cavitation in a fuel injector will help in understanding the phenomenon and will assist in further development.

The construction of any simulation of cavitating …

The Allen Telescope Array Search For Electrostatic Discharges On Mars, Marin M. Anderson, Andrew P.V. Siemion, William C. Barott, Geoffery C. Bower, Gregory T. Delory, Imke De Pater, Dan Werthimer

Department of Electrical Engineering and Computer Science - Daytona Beach

The Allen Telescope Array was used to monitor Mars between 2010 March 9 and June 2, over a total of approximately 30 hr, for radio emission indicative of electrostatic discharge. The search was motivated by the report from Ruf et al. of the detection of non-thermal microwave radiation from Mars characterized by peaks in the power spectrum of the kurtosis, or kurtstrum, at 10 Hz, coinciding with a large dust storm event on 2006 June 8. For these observations, we developed a wideband signal processor at the Center for Astronomy Signal Processing and Electronics Research. This 1024 channel spectrometer calculates …