The fEashback tendency of premixed fames of gaseous fuels with air may be estimated by considering the limiting value of the so-called 'flashback gradient' as a function of burning velocity, up to the distance from the walls within wkich flashback can occur.
It is known from Grumer's work that the flashback gradient of mixtures of hydrocarbons can be calculated using the weighted averages of the gradients of the various pure components.
These additive properties disappear completely if hydrogen is a component of the gaseous mixture.
Therefore it was decided to use a linear relationship in which the components accompanying hydrogen were given typical $xed coefficients while hydrogen was accorded a variable coefficient.
From Grumer's experimental data it may be assumed that the anomalous behaviour of hydrogen. when mixed with other combustible components, is strongly injluenced by the stoichiometric air value of the gaseous mixture. Thus a satisfactory linear formula was developed.
First tests were carried out with mixtures containing hydrogen, methane, propane and propylene, the combustible gas being mixed with air in stoichiometric ratio. An example of the calczllation of a flashback gradient is given where experimental and calculated values can be compared: reasonable agreement is found.