Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Effect of Buoyancy on the Radiative Extinction Limit of Low-Strain-Rate Nonpremixed Methane-Air Flames

Published

Author(s)

Anthony P. Hamins, Matthew F. Bundy, C B. Oh, Sung C. Kim

Abstract

The structure and extinction of nonpremixed flames were investigated through comparison of experiments and calculations using a counterflow configuration. Experiments were conducted at the NASA Glenn Research Center's 2.2-s drop tower to attain suppression and temperature measurements in low-strain nonpremixed methane-air microgravity flames. Suppression measurements using nitrogen added to the fuel stream were performed for global strain rates from 7 to 50 s-1. Judicious hardware selection and an optimized experimental procedure facilitated rapid, controllable, and repeatable flame extinction measurements. The minimum nitrogen volume fraction in the fuel stream needed to ensure suppression for all strain rates in microgravity was measured to be 0.855 - 0.016, associated with the turning point, which occurred at a global strain rate of 15 s?1. This value was higher than the analogous value in normal gravity. Flame temperature measurements were attained in the high-temperature region of the flame (T >1200 K) using visible emission from a SiC filament positioned axially along the burner centerline. The suppression and temperature measurements were used to validate a two-dimensional flame simulation developed here, which included buoyancy effects and finite-rate kinetics. The simulations yielded insight into the differences between microgravity and normal gravity suppression results and also explained the inadequacy of the one-dimensional model results to explain the microgravity suppression results.
Citation
Combustion and Flame
Volume
151
Issue
No. 1/2

Keywords

nonpremixed flames, buoyancy, extinction, flame structure, microgravity, experiments, fire suppression, temperature measurements, nitrogen, flame extincuishment, gravity, equations, heat release

Citation

Hamins, A. , Bundy, M. , Oh, C. and Kim, S. (2007), Effect of Buoyancy on the Radiative Extinction Limit of Low-Strain-Rate Nonpremixed Methane-Air Flames, Combustion and Flame, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=909591 (Accessed March 28, 2024)
Created October 1, 2007, Updated February 19, 2017