Dissertation/Thesis Abstract

Dual-Pump CARS Development and Application to Supersonic Combustion
by Magnotti, Gaetano, Ph.D., The George Washington University, 2012, 300; 3548004
Abstract (Summary)

Successful design of hypersonic air-breathing engines requires new computational fluid dynamics (CFD) models for turbulence and turbulence-chemistry interaction in supersonic combustion. Unfortunately, not enough data are available to the modelers to develop and validate their codes, due to difficulties in taking measurements in such a harsh environment.

Dual-pump coherent anti-Stokes Raman spectroscopy (CARS) is a non-intrusive, non-linear, laser-based technique that provides temporally and spatially resolved measurements of temperature and absolute mole fractions of N2, O2 and H2 in H2-air flames. A dual-pump CARS instrument has been developed to obtain measurements in supersonic combustion and generate databases for the CFD community. Issues that compromised previous attempts, such as beam steering and high irradiance perturbation effects, have been alleviated or avoided. Improvements in instrument precision and accuracy have been achieved.

An axis-symmetric supersonic combusting coaxial jet facility has been developed to provide a simple, yet suitable flow to CFD modelers. The facility provides a central jet of hot "vitiated air" simulating the hot air entering the engine of a hypersonic vehicle flying at Mach numbers between 5 and 7. Three different silicon carbide nozzles, with exit Mach number 1, 1.6 and 2, are used to provide flows with the effects of varying compressibility. H2 co-flow is available in order to generate a supersonic combusting free jet. Dual-pump CARS measurements have been obtained for varying values of flight and exit Mach numbers at several locations. Approximately one million Dual-pump CARS single shots have been collected in the supersonic jet for varying values of flight and exit Mach numbers at several locations. Data have been acquired with a H2 co-flow (combustion case) or a N 2 co-flow (mixing case). Results are presented and the effects of the compressibility and of the heat release are discussed.

Indexing (document details)
Advisor: Cutler, Andrew D.
Commitee: Bardet, Philippe M., Danehy, Paul M., Keidar, Michael, Miller, John H.
School: The George Washington University
Department: Mechanical and Aerospace Engineering
School Location: United States -- District of Columbia
Source: DAI-B 74/05(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Aerospace engineering
Keywords: Coherent anti-Stokes Raman spectroscopy, Compressible flows, Laser diagnostics, Scramjets, Supersonic combustion
Publication Number: 3548004
ISBN: 9781267831798
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