*Simon, Dorothy M., Belles, Frank E.*

*naca-rm-e51l18*

*1952*

An equation for quenching distance based on the destruction of chain carriers by the surface is derived. The equation expresses the quenching distance in terms of the diffusion coefficients and partial pressures of the chain carriers and gas phase molecules, the efficiency of the surface as a chain breaker, the total pressure of the mixture, and a constant which depends on the geometry of the quenching surface. Quenching distances measured by flashback for propane-air flames are shown to be consistent with the mechanism. The derived equation is used with the lean inflammability limit and a rate constant calculated from burning velocity data to estimate quenching distances for propane-air (hydrocarbon lean) flames satisfactorily.

*An Adobe Acrobat (PDF) file of the entire report:*

http://naca.central.cranfield.ac.uk/reports/1952/naca-rm-e51l18.pdf