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 10 of 10 for “"near nozzle"”.
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Very near-nozzle shear-layer turbulence and jet noise
Jet noise is sensitive to nozzle configurations and most current aircraft operate close to Federal Aviation Administration (FAA) and other noise restriction levels, with more stringent requirements expected in the future. At the current time, however, prediction capabilities lack the fidelity to …
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Study of High-speed Subsonic Jets using Proper Orthogonal Decomposition
… issued through baseline axisymmetric conical nozzle and ones with chevrons. The analysis is done using flow velocity data obtained through Particle Image Velocimetry (PIV). Two chevron nozzles with penetration levels at 2% and 4% are used. The mean velocity and TKE results show that chevrons …
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Simulations And Experiments Of Fuel Injection, Mixing And Combustion In Di Gasoline Engines
… intensity. The characterizations of the internal nozzle flow of DI injector are first studied using the multidimensional computational fluid dynamic (CFD) simulation. In the meanwhile the numerical and experimental studies are carried out to observe the external spray and wall impingements in an …
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The Turbulence Structure of Heated Supersonic Jets with Offset Total Temperature Non-Uniformities
… the shear layer turbulence were observed in the near nozzle region of the thermally offset jet when compared to the uniform jet case. The changes result in a thickening of the shear layer nearest the location of the cold plume which alters the integral length scales of the coherent turbulent …
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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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Development of Specialized Laser Doppler Velocimeters for High Resolution Flow Profile and Turbulence Spectral Measurements
… in a flat plate turbulent boundary layer very near the wall have compared favorably to data from previous studies. The second paper focuses on the motion and evolution of coherent structures in supersonic jet flows and how that relates to the intense noise the flows generate. As a preliminary …
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Crackle noise from high-speed free-shear-flow turbulence
… to assess the underlying mechanisms and quantify near-field nonlinearity as potential sources of the radiated wave field, especially the pressure skewness. Though the DNS is restricted to a modest Reynolds-number range, the simulated turbulence is shown to have a broad range of scales and …
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On the turbulence-generated sound and control of compressible mixing layers
… generation and mixing characteristics of the near-nozzle region of jets. This work presents three separate but related studies that investigate sound generation and active control for noise mitigation and mixing enhancement of such mixing layers. High-fidelity direct numerical simulations of …
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Fuel spray modelling in direct-injection diesel and gasoline engines
… present in the crucial region close to the nozzle exit of fuel injection systems. Moreover, the mathematical formulation of the Eulerian-Lagrangian models is intrinsically related to critical numerical issues, like the difficulty of correctly estimating the initial conditions at the nozzle …