ABSTRACT
The problem of fl ame quenching by a wall was fi rst studied nearly two centuries ago by Sir Humphry Davy when he was involved in preventing explosions in coal mines. He used an experimental approach that took him several months to solve the problem of the mining safety lamp. He then demonstrated its construction to the public [1]. After this spectacular achievement, fl ame quenching by walls was neglected by science for more than a 100 years. It was only in 1918 that Payman and Wheeller published their work on the propagation of fl ames through small diameter tubes [2]. Extensive experimental studies of fl ame quenching were also undertaken by Holm [3], who was the fi rst to introduce the concept of quenching distance or quenching diameter. However, the most important contribution to the theory of fl ame quenching by walls was made by Zel’dovich [4,5]. He demonstrated that at the quenching limit, SL,lim, the laminar burning velocity, and the maximum value of the limit fl ame temperature, (Tb,max)lim were related to their respective values under adiabatic conditions, S°L , and T b°
, through the relations
= =
S e
S (6.1.1)
( )⎡ ⎤Δ ≡ − = =⎣ ⎦ 2
T Rb T T T
ES
(6.1.2)
where b a parameter characterizing heat losses, R the universal gas constant, E the activation energy.
