Two recent communications in Nature1,2 have discussed the effect of pressure upon burning velocity and have referred to the square root law of Tanford and Pease3 as leading "to the inverse fourth root law for the variation of velocity with pressure". This statement is not strictly true. The square root law, after a number of simplifying assumptions, predicts that the burning velocity should vary with pressure as the square root of Σ 'xi/Bi', where xi is the mol fraction of an active species at the equilibrium surface, and Bi is a factor previously defined4, which is comparatively invariant with pressure. Where hydrogen atoms carry most of the burden of energy transfer into unburnt gas, we should expect xH to vary approximately as the inverse square root of the pressure, and, hence, roughly an inverse fourth root variation of burning velocity. For precise calculation, however, equilibrium computation of the xi is required. One mixture for which such a calculation has been made is stoichiometric butadiene – air5. The calculated burning velocity ratio for one atmosphere as against half an atmosphere pressure was found to be 0.88, as compared to a fourth root value of 0.84. Thus, as Gaydon and Wolfhard6 point out, the burning velocity may decrease with pressure less sharply than a fourth-root relation would predict.
This is a preview of subscription content, access via your institution
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Rent or buy this article
Get just this article for as long as you need it
Prices may be subject to local taxes which are calculated during checkout
Linnett and Wheatley, Nature, 164, 403 (1949).
Gaydon and Wolfhard, Nature, 164, 404 (1949).
Tanford and Pease, J. Chem. Phys., 15, 861 (1947).
Tanford, J. Chem. Phys., 15, 433 (1947).
Badin, Stuart and Pease, J. Chem. Phys., 17, 314 (1949).
Gaydon and Wolfhard, Proc. Roy. Soc., A, 196, 105 (1949).
Ubbelohde and Anwandter, J. Gasbel., 60, 225 (1917).
Rights and permissions
About this article
Cite this article
TANFORD, C. Effect of Pressure on Burning Velocity. Nature 164, 884–885 (1949). https://doi.org/10.1038/164884b0
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.