Sukruth Somappa
(Advisor: Prof. Tim Lieuwen]

will propose a doctoral thesis entitled,

Dynamics of finite thickness and harmonically forced turbulent premixed flames

On

Monday, November 1 at 12:00 p.m.
 Food Processing Building, Room 102

 [North Avenue Research Area, 640 Strong Street, Atlanta, GA 30318]
 

Abstract
Turbulent combustion investigates the interactions of broadband fluid dynamic disturbances and combustion. It forms an important aspect in the design and operation of modern combustion devices. This proposal considers two aspects of turbulent premixed combustion: first, the interaction of broadband turbulent and narrowband acoustic/harmonic disturbances and next, the propagation speeds of finite thickness turbulent flames.

First, the interaction of turbulent fluctuations (broadband in nature) and coherent disturbances (narrowband in nature) is considered. This superposition generally arises in shear flows or in confined environments. This potentially non-linear interaction, ubiquitously found in practical combustion devices is seldom explored in literature. In particular, for a turbulent premixed v-flame stabilized at a harmonically oscillating flame holder, prior studies have shown that the ensemble-averaged flame speed varies along the flame. In addition, the flame speed has been shown to be correlated with the curvature of the coherent wrinkle. This sensitivity of the turbulent flame speed to curvature, “turbulent Markstein length” is proposed to be quantified using expanded experimental regime. In addition, its dependence on various flame/flow dynamic parameters is proposed to be explored.

Next, a modelling study to investigate finite thickness effects on turbulent flame speed is considered. Infinitely thin, turbulent flames satisfy constraints required for uniformly travelling wave solutions to the reaction diffusion equation. In that case, the flame speed is completely controlled by the leading edge. These flames thus can be termed as ‘pulled’ fronts. However, the behavior of such fronts is not established for source functions which deviate from such constraints. This deviation for turbulent flames can occur due to finite thickness and Arrhenius kinetics. Such effects on turbulent flame speeds are proposed to be explored using a combination of exact solutions, computational and variational techniques.

Committee

• Prof. Tim Lieuwen – School of Aerospace Engineering (advisor)
• Prof. Jechiel Jagoda – School of Aerospace Engineering
• Prof. Adam Steinberg – School of Aerospace Engineering