Details

Autor(en) / Beteiligte

• Bradley, D.
• Lawes, M.
• Liu, Kexin
• Woolley, R.

Titel

The quenching of premixed turbulent flames of iso-octane, methane and hydrogen at high pressures

Ist Teil von

• Proceedings of the Combustion Institute, 2007, Vol.31 (1), p.1393-1400

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2007

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Experimental and theoretical studies are reported of turbulent flame quenching, with premixed flames of methane–air, iso-octane–air and hydrogen–air. Mixtures were exploded in a fan-stirred explosion bomb in which the rms turbulent velocity was varied by changes in fan speed. Influences of Markstein number, pressure up to 1.5 MPa, and Karlovitz stretch factor, K, were studied. It was found that the ratio of the positive stretch rate for extinction of the laminar flame to the rms turbulent strain rate was an important parameter. Probabilities of flame propagation, p f, from an initial kernel were measured. The conditions for probabilities of 0.8 and 0.2 were correlated in terms of the Karlovitz stretch factor and Markstein number. However, at a given p f, the theoretical probability, P bf, that the spectrum of stretch rates for a turbulent flame would support propagation, declined with increase in K. This theoretical probability assumed a positive flame stretch rate for quenching equal to that for the extinction of a steady-state laminar flame. Its declining value with K, at constant p f, was attributed, at least in part, to the inability of non-steady-state flamelets of the turbulent flame to respond to transient excursions of flame stretch rates to values in excess of those that extinguish laminar flames. Another possibility was that the highly convoluted flames were able to follow a route through regions of sufficiently low stretch rate to avoid extinctions.