Organizational Unit:

Daniel Guggenheim School of Aerospace Engineering

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https://hdl.handle.net/1853/70742

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Organizational Unit

College of Engineering

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Organizational Unit

Aerospace Design Group

Organizational Unit

Aerospace Systems Design Laboratory (ASDL)

Organizational Unit

Air Transportation Laboratory

Organizational Unit

Cognitive Engineering Center

Organizational Unit

Space Systems Design Laboratory (SSDL)

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https://finding-aids.library.gatech.edu/agents/corporate_entities/106

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Publication Search Results

Now showing 1 - 10 of 127

Probabilistic evaluation of finite element response (PREFER) for Georgia

(Georgia Institute of Technology, 2006-12-30) Mavris, Dimitri N.
LES of sooting flames

(Georgia Institute of Technology, 2006-12-29) Menon, Suresh ; El-Asrag, Hossam
Development and implementation of a capability-planning framework

(Georgia Institute of Technology, 2006-12-21) Mavris, Dimitri N.
Flow field/mixing characterization of 9H fuel nozzle

(Georgia Institute of Technology, 2006-12-01) Lieuwen, Timothy C.
A Systematic Process for Adaptive Concept Exploration

(Georgia Institute of Technology, 2006-11-29) Nixon, Janel Nicole

This thesis presents a method for streamlining the process of obtaining and interpreting quantitative data for the purpose of creating a low-fidelity modeling and simulation environment. By providing a more efficient means for obtaining such information, quantitative analyses become much more practical for decision-making in the very early stages of design, where traditionally, quants are viewed as too expensive and cumbersome for concept evaluation. The method developed to address this need uses a Systematic Process for Adaptive Concept Exploration (SPACE). In the SPACE method, design space exploration occurs in a sequential fashion; as data is acquired, the sampling scheme adapts to the specific problem at hand. Previously gathered data is used to make inferences about the nature of the problem so that future samples can be taken from the more interesting portions of the design space. Furthermore, the SPACE method identifies those analyses that have significant impacts on the relationships being modeled, so that effort can be focused on acquiring only the most pertinent information. The results show that the combination of a tailored data set, and an informed model structure work together to provide a meaningful quantitative representation of the system while relying on only a small amount of resources to generate that information. In comparison to more traditional modeling and simulation approaches, the SPACE method provides a more accurate representation of the system using fewer resources to generate that representation. For this reason, the SPACE method acts as an enabler for decision making in the very early design stages, where the desire is to base design decisions on quantitative information while not wasting valuable resources obtaining unnecessary high fidelity information about all the candidate solutions. Thus, the approach enables concept selection to be based on parametric, quantitative data so that informed, unbiased decisions can be made.
CDA Workshop #4 - Agenda

(Georgia Institute of Technology, 2006-11-28) Clarke, John-Paul B.

Agenda for 4th JPDO EWG Operations Workshop (4th CDA Workshop).
Two component LDV test results for GE 9FB burner nozzle

(Georgia Institute of Technology, 2006-11-28) Lieuwen, Timothy C. ; Scarborough, David ; Gray, Joshua ; Noble, Bobby
Simulations of a Sub-scale Liquid Rocket Engine: Transient Heat Transfer in a Real Gas Environment

(Georgia Institute of Technology, 2006-11-21) Masquelet, Matthieu M.

The prediction of transient phenomena inside Liquid Rocket Engines (LREs) has not been feasible until now because of the many challenges posed by the operating conditions inside the combustion chamber. Especially, the departure from ideal gas because of the cryogenic injection in a high-pressure chamber is one of the ma jor hurdle for such simula- tions. In order to begin addressing these issue, a real-gas model has been implemented in a massively parallel flow solver. This solver is capable of performing Large-Eddy Simula- tions (LES) in geometrical configurations ranging from an axisymmetric slice to a 3D slice up to a full 3D combustor. We present here the results from an investigation of unsteady combustion inside a small-scale, multi-injectors LRE. Both thermally perfect gas (TPG) and real gas (RG) approaches are evaluated for this LOX-GH2 system. The Peng-Robinson cubic equation of state (PR EoS) is used to account for real gas effects associated with the injection of cryogenic oxygen. Realistic transport properties are computed but simplified chemistry is used in order to achieve a reasonable turnaround time. Results show the impor- tance of the unsteady dynamics of the flow, especially the interaction between the different injectors. The role of the equation of state is assessed and the real gas model, despite a limited zone of application, seems to have a strong influence on the overall chamber behav- ior. Although several features in the simulated results agree well with past experimental observations, the prediction of heat flux using a simplified flux boundary condition is not completely satisfactory. This work also reviews in details the state of our knowledge on supercritical combustion in a coaxial injector configuration, stressing issues where numeri- cal modeling could provide new insights. However, many developments and improvements are required before an LES modeling of such a flow is both feasible and valid. We finally propose a comprehensive roadmap towards the completion of this goal and the possible use of CFD as a design tool for a modern liquid rocket engine.
Vibration and Aeroelastic Analysis of Highly Flexible HALE Aircraft

(Georgia Institute of Technology, 2006-11-20) Chang, Chong-Seok

The highly flexible HALE (High Altitude Long Endurance) aircraft analysis methodology is of interest because early studies indicated that HALE aircraft might have different vibration and aeroelastic characteristics from those of conventional aircraft. Recently the computer code Nonlinear Aeroelastic Trim And Stability of HALE Aircraft (NATASHA) was developed and used to the flight dynamics and aeroelastic analysis of flying wing HALE aircraft. Further analysis improvements were required to extend its capability to the ground vibration test (GVT) environment and to both GVT and aeroelastic behavior of HALE aircraft with other configurations. First, the geometrically exact fully intrinsic beam theory was extended to treat other aircraft configurations modeled as an assembly of beam elements. It includes auxiliary elevator input in the horizontal tail and fuselage aerodynamics. Second, the methodology was extended to treat the GVT environment to provide modal characteristics for model validation. A newly developed bungee formulation is coupled to the intrinsic beam formulation for the GVT modeling. After the coupling procedures, the whole formulation cannot be fully intrinsic because the geometric constraint by bungee cords makes the system statically indeterminant. Third, because many HALE aircraft are propeller driven, the methodology was extended to include an engine/nacelle/propeller system using a two-degree-of-freedom model. This step was undertaken to predict a dynamic instability called ``whirl flutter," which can be exhibited in such HALE aircrafts. For simplicity, two fundamental assumptions are made: constant approximation on the propeller aerodynamics and the use of equivalent three-bladed counterpart for two-bladed propeller system to obviate the need for Floquet theory. The validity of these assumptions is verified by investigating the periodic effect of side forces and hub moments and the periodic inertia effect. Finally, parametric studies show how the current methodology can be utilized as a unified preliminary analysis tool for the vibration and aeroelastic analysis of highly flexible HALE aircraft.
Large Eddy Simulation of a High Aspect Ratio Combustor

(Georgia Institute of Technology, 2006-11-20) Kirtaş, Mehmet

The present research investigates the details of mixture preparation and combustion in a two-stroke, small-scale research engine with a numerical methodology based on large eddy simulation (LES) technique. A major motivation to study such small-scale engines is their potential use in applications requiring portable power sources with high power density. The investigated research engine has a rectangular planform with a thickness very close to quenching limits of typical hydrocarbon fuels. As such, the combustor has a high aspect ratio (defined as the ratio of surface area to volume) that makes it different than the conventional engines which typically have small aspect ratios to avoid intense heat losses from the combustor in the bulk flame propagation period. In most other aspects, this engine involves all the main characteristics of traditional reciprocating engines. A previous experimental work has identified some major design problems and demonstrated the feasibility of cyclic combustion in the high aspect ratio combustor. Because of the difficulty of carrying out experimental studies in such small devices, resolving all flow structures and completely characterizing the flame propagation have been an enormously challenging task. The numerical methodology developed in this work attempts to complement these previous studies by providing a complete evolution of flow variables. Results of the present study demonstrated strengths of the proposed methodology in revealing physical processes occurring in a typical operation of the high aspect ratio combustor. For example, in the scavenging phase, the dominant flow structure is a tumble vortex that forms due to the high velocity reactant jet (premixed) interacting with the walls of the combustor. LES gives the complete evolution of this flow structure, from its beginning to its eventual decay after the scavenging period is over. In addition, LES is able to predict the interaction between the bulk flow at top dead center (TDC) and the turbulent flame propagation. The success of this depends on the ability of the model in predicting turbulent flow structure including its length and velocity scales.