Organizational Unit:
Daniel Guggenheim School of Aerospace Engineering

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Now showing 1 - 10 of 347
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Dynamic modeling of plasma effects during multi-phase detonations near a surface and/or in a magnetic field

2013-12 , Menon, Suresh , Schulz, Joseph

A multi-physics model has been developed to simulate detonations and condensed-phase explosions in the presence of an external electromagnetic field. To simulate these effects, models for high-temperature gas physics, plasma-production, dispersed-phase mixing, and turbulence have been implemented within the framework of a numerical method capable of simulating magnetohydrodynamic (MHD) flows. This research has leveraged past work in MHD flows, detonations, and turbulence-chemistry interactions to study multi-scale detonation-plasma-field interactions, and has furthered the understanding of many key physical processes of these flows. This work targeted three main basic science objectives: the study of plasma-production by detonations and condensed-phase explosions, the study of MHD instabilities and turbulence relevant to post-detonation flows, and the study of how a detonation is affected by the presence of a magnetic field. Simulations indicate that gaseous detonation waves generate a weakly ionized plasma in the post-detonation region. The average electrical conductivity in the post-detonation flow, however, is of the order of 10-3 S/m, and practical engineering applications involving the use of MHD forces to manipulate the flow for generation of electrical power, propulsive thrust, etc., require higher levels of electrical conductivity. Simulations of mixtures seeded with particles of a low ionization potential show a substantial increase the flow's electrical conductivity. The presence of these particles can adversely affect the detonation propagation. The physics of how an electromagnetic field interacts with the conducting products of a detonation, and how that interaction might affect the stability and propagation of the detonation wave is systematically studied. The magnetic field applied in the direction of detonation propagation affects the detonation through a combined effect of Joule heating and Lorentz force, in some cases altering the cellular structure of the detonation completely by reducing the half-reaction zone thickness. Basic studies of the Richtmyer-Meshkov instability, an important mechanism for the transition to turbulence in explosions, are used to elucidate several salient features of these types of MHD flows. Namely, simulations show that the presence of a dispersed phase alters the mixing growth-rates of the instability, and furthermore, an applied magnetic field is shown to either suppress or enhance fluid mixing.

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On-demand aircraft conceptual design and development

2013-01 , German, Brian J.

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Hybrid solution-adaptive unstructured Cartesian method for large-eddy simulation of detonation in multi-phase turbulent reactive mixtures

2012-03 , Menon, Suresh , Gallagher, Timothy , Muralidharan, Balaji

A class of problems of both great fundamental interest and practical relevance is in the field of highly compressible turbulent flows of multi-fluids. Shock interaction with turbulence and/or flames have many practical applications and require advanced computational techniques. This report summarizes the work done to date to develop methods and algorithms for hybrid structured-unstructured methods in large-eddy simulations (LES). Particular emphasis is given to efficiency and accuracy while using techniques applicable to solution-adaptive approaches. The formulation and algorithm for statically refined grids for DNS and LES is shown to be robust and allows rapid inclusion in existing solvers with a minimal change in code base while also ensuring compatibility with existing features. Extensions to solution-adaptive techniques from the static approach are discussed. The application of the method to numerous flow examples demonstrates the capability and robustness of the method. Finally, an adaptive Cartesian method using level-sets and cut-cells to solve the interactions of complex, deforming and reacting bodies in a compressible flow field is developed and validated.

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System-wide reliability and life cycle cost model for turbomachinery ...

2011-12-06 , Volovoi, Vitali V.

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Cross fire simulation rig

2013-03 , Zinn, Ben T. , Lubarsky, Eugene

The primary purpose of the project was to investigate the threshold for flame propagation between two combustors of crossfire rig designed to simulate conditions in a GE gas turbine engine.

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State-of-the-art rotor aerodynamics and shipboard rotorcraft flight simulation

2012-09 , Prasad, Jonnalagadda V. R. , Sankar, Lakshmi N.

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Advanced methods for intelligent flight guidance and planning in support of pilot decision making

2012-03-01 , Tsiotras, Panagiotis , Johnson, Eric N.

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Experimental studies of JTECH power generation in a scramjet

2013-03 , Menon, Suresh , Berlette, J. , Scarborough, D.

An analysis of the thermodynamics of the proposed Johnson Thermoelectric Energy Converter (JTEC) device as if it was placed in the walls of the combustor of a supersonic combustion ramjet.

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A novel augmentor that does not use flame holders to stabilize the combustion process

2012-06 , Zinn, Ben T. , Lubarsky, Eugene , Neumeier, Yedidia , Williams, Aimee

This report describes the process of determining auto-ignition delay of the liquid Jet-A aviation fuel injected in a cross flow of vitiated air. Auto-ignition delays were measured by processing of the time-averaged chemiluminescence images for a range of temperatures from 898-1028K, vitiated oxygen percentages from 9.3% to 12.2%, velocities from 80 – 140 m/s and global Jet-A to, vitiated-air mixture equivalence ratios from φ=0.3 to φ=1.5. It was found that ignition delay increases exponentially from one to ten milliseconds with inverse temperature variation and are more scattered at lower temperatures. The data obtained in this study reveals delay times much shorter than those measured in most of other studies, but with same character of dependence upon the temperature of the flow.

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Enhanced modeling and analysis for technology cost-benefit estimation

2011-12-31 , Mavris, Dimitri N.