Partially premixed tubular flames: an experimental survey

Abstract

Turbulent combustion, as seen in practical combustors, is highly complex and beyond current numerical means to accurately simulate. Simplifying assumptions commonly used in computational models approximate the complexity of small scale reaction and mixing to reduce computational cost, but these estimates cost accuracy. It is a necessity to understand fundamental aspects of combustion and what approximations do not sacrifice accuracy while reducing computational expenses. The study of laminar flames allows full simulation of chemical kinetics and transport, and evaluation of combustion phenomena.

The experimental work to follow presents characterization of partially premixed tubular flames containing premixed hydrogen-air streams imposed on fuels diluted by carbon dioxide. The tubular flame structures are novel, containing distinct zones of premixed and diffusion flames. Flames have resemblance to turbulent flames, - local extinction zones, varying curvature, and zones of enhancement, - while existing in a steady-state and allowing detailed laser diagnostics of flame structure.

Due to the novelty of partially premixed tubular flames, the objectives of the research to follow are: 1) parametrically survey and analyze stable flame geometry via chemiluminescence and 2) perform non-intrusive Raman spectroscopy on select cases to develop a fundamental understanding of flame composition as a foundation for numerical comparison and validation.