Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 264 for “"Engineering, Aerospace"”.
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Hydroxyl-Radical Planar Laser-Induced Fluorescence Imaging of Turbulent Supersonic Combustion
Flow visualisation and statistical analysis of a supersonic, turbulent reacting flow from non-intrusive hydroxyl radical (OH) planar laser-induced fluorescence (PLIF) images are presented. The OH PLIF images show instantaneous structures of turbulence in two combustor configurations at different …
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On the Rumpling Instability in Thermal Barrier Systems
"Thermal barrier coatings (TBCs) are protective multi-layered metal-ceramic coatings used in hot sections of jet engines and gas turbines. The TBCs are composed of a superalloy substrate, an intermediate metallic bond coat (BC) and a ceramic topcoat. The TBCs are beset by reliability problems …
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Jet Noise Control by Adjoint-Based Optimization
"The adjoint of the perturbed and linearized compressible viscous flow equations is formulated in such a way that its solution can be used to optimize control actuation in order to reduce the noise radiated by a randomly excited two-dimensional mixing layer, which serves as near-nozzle model of a …
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Acoustic Resonances in Ducted Jet Systems
The results of selected test cases are presented and the main features of resonant and non-resonant regimes for this model problem are discussed. A high-amplitude resonance, qualitatively similar to experiments in more complex geometries, was observed for a symmetric overexpanded M jet 1.2. It is …
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The Structure of Turbulence Over Smooth and Rough Walls
Several spanwise lengthscales are shown to vary linearly with distance from the wall, revealing self-similar growth of spanwise structure in an average sense. However, inspection of the data suggests individual structures do not grow strictly self-similarly in time. It is proposed that additional …
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Estimation of Adhesive Bond Strength in Laminated Safety Glass Using Guided Mechanical Waves
Based upon the guided wave energy velocity predictions for each of the laminates with different levels of adhesion, the S0 mode was selected as the most promising for use in nondestructively estimating adhesion levels in laminated safety glass. The predicted energy velocities (obtained using this …
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Quantifying Air Distribution, Ventilation Effectiveness and Airborne Pollutant Transport in an Aircraft Cabin Mockup
The health, safety and comfort of passengers during flight inspired this research into cabin air quality, which is closely related to its airflow distribution, ventilation effectiveness and airborne pollutant transport. The experimental facility is a full-scale aircraft cabin mockup. A volumetric …
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Airflow Analysis in Mechanically Ventilated Obstructed Rooms
It was concluded that for typical room flowrates and inlet types the room air distribution system is obstruction ratio independent. Local velocities and standard deviations varied with each obstruction setup and inlet combination. However, average air velocities and turbulence intensities were not …
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Effects of Supercooled Large -Droplet Icing on Airfoil Aerodynamics
The effects of simulated ice shape on the NLF 0414 were quite different from the NACA 23012m. There was little variation of lift when the simulated ice-shape location was varied from 2% to 20% chord. The large losses in lift occurred when the ice shape was located downstream of 30% chord, and the …
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Collocation With Nonlinear Programming for Two-Sided Flight Path Optimization
This research successfully develops a new numerical method for the problem of two-sided flight path optimization, that is, a method capable of finding trajectories satisfying the necessary condition of an open-loop representation of a saddle-point trajectory. The method of direct collocation with …
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Development of S3D and Adjoint Design Methods for Efficient Aerodynamic Design of Three-Dimensional High-Speed Compressor Blades
In the second part of the study, an adjoint design method was employed for compressor design to broaden the range of design capability, to facilitate 3D design applications, and to complement the S3D design method. An adjoint design code was developed, based on a 3D compressor flow analysis code, …
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An Analytical Asymptotic Solution Method of the Euler Equations for Efficient Flow Analysis and Aerodynamic Design
An efficient flow analysis and aerodynamic design tool was developed based on analytical asymptotic solutions of the Euler equations. The solution algorithm uses an analytical asymptotic formulation in the streamline coordinate system, wherein the governing equations are transformed into a …
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Wake Survey Techniques for Objects With Highly Turbulent Wakes
This dissertation for the first time analyzed the turbulence effect on the simplified Jones' equation with measurements using a Pitot probe, and found that this method includes a portion of the turbulence effect into account implicitly, depending on the nose shape of the probe. A method for …
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Numerical Simulation of Turbulent Particle Diffusion
To accurately simulate particles in wall-bounded flows with the CRW model, a modified Markov chain based on a normalized velocity fluctuation was found to be important to avoid unphysical wall-ward particle fluxes. Also, the incremental drift velocity for the Markov chain (required for …
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Magnetostrictive Particle Tagging of Epoxy and Epoxy Composites for Self Assessment of Damage
"This study is a comprehensive look at the feasibility of using magnetostrictive tags to detect damage in a structural composite. The brittle nature of the failure process of polymer matrix composite poses a technical challenge for their introduction in structural applications. Thus, there is a …
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A Hybrid Inverse Design Method for Complex Aerodynamic and Hydrodynamic Geometries
Five examples, showing both lifting and non-lifting bodies, are presented. The final two examples demonstrate how the method can be applied to the design of geometries consisting of several components. The method was able to produce the desired aerodynamic and geometric characteristics for all the …
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Structural Behavior of Nitinol Microflaps
Finite element models of the SMAT microflap and DMA specimens were created by incorporating a user material subroutine SMA-UMAT in ABAQUS. Model results were verified by correlation with the DMA experimental results. The structural behavior of a SMAT microflap was then analyzed and the results were …
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Reentry Vehicle Aerodynamics and Control at Very High Angle of Attack
In recent flight tests the X-38 reentry test vehicle spins during the deployment of the drogue parachute. An experimental aerodynamic study has been conducted at the University of Illinois using a scale model of the X-38 to explore the cause of this problem. A six-component sting balance was used …
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Efficient Trajectory Optimization Procedure for Designing Solar -Electric Propulsion, Gravity -Assist Outer -Planet Missions
A performance (delivered mass versus time of flight) estimation technique approximates the performance of different revolution ratio trajectories from a set of optimal trajectories using a linear least square fitting method. This technique brings further understanding of the effect of different …
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Improved Collocation Methods With Application to Six -Degree -of -Freedom Trajectory Optimization
… This code constitutes a much-improved tool for aerospace vehicle design but has application to all two-timescale optimization problems.
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