Graduation Semester and Year

2011

Language

English

Document Type

Thesis

Degree Name

Master of Science in Aerospace Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Luca Massa

Abstract

A numerical study was performed to investigate the effect of preshock turbulence on the detonation wave properties. A direct numerical simulation was performed on the chemically reactive Navier-Stokes equations using a Runge-Kutta scheme and a fifth-order WENO spatial discretization. We performed a direct numerical simulation (DNS) which belongs to the domain of Computational Fluid Dynamics (CFD), of the fluid mechanics equations in three dimensions to determine the fine scale evolution. A simple one-step chemical kinetics model was used in the study.The main objective of the research is to examine the behavior of the turbulence when subjected to a strong shock with heat release. The evolution of the turbulent Mach number, lengthscales (Taylor microscale and Kolmogorov scale), turbulent kinetic energy, Reynolds stress, auto- and cross-correlations with heat release and activation energy is examined. Shock turbulence interaction has been the subject of research for over the decades but there is no significant study has not yet been made on Detonation Turbulence interaction. This novel research is quite very helpful in practical applications of Aerospace industry i.e by safe handling of the fuels, promoting detonations for detonation engines etc..The results show a marked influence of preshock perturbations on the postshock statistics. Detonation-Turbulence interaction resulted in higher amplifications of turbulence statistics and parameters like Turbulent Mach number, Turbulent length scales (i.e. Taylor microscale, Kolmogorov length scale etc.), Turbulent kinetic energy, root mean square velocity (rms velocity), auto-correlation, cross correlation functions etc. Detonation event triggers a self excited instability, evidenced by the velocity fluctuations and further by space time correlation functions. Also, the alteration to the limit cycle structure supported by unstable waves close to their critical points is highlighted. The effect of reactivity and fluid acceleration in the postshock region are examined by comparison with the non-reactive analog. The possibility that significant forcing can lead to hot spot formation is investigated by considering temperature probability distribution functions in the reaction zone. The separate effect of vortical and entropic fluctuations is considered.

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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