Correlation of the Height of Turbulent Choked Jet Flames

D. Bradley1,a, J. Casal2 and A. Palacios1,2

1School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK.

2Centre for Technological Risk Studies, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Barcelona 08028, Catalonia, Spain


Correlations are first reviewed of flame height for jet flames at atmospheric pressure, in the absence of cross winds. At low jet flow rates buoyancy effects are important and correlations have been expressed in terms of Froude number. At high flow rates, correlations have involved release pressures, mass flow rates and Reynolds number. The present paper addresses the problem of correlating the height of choked flow jet flames for a variety of initial pressures and pipe diameters for C3H8, CH4 and H2. A number of existing correlations, whilst successful for each gas separately, could not embrace all three. Studies of the turbulent burning velocity, involving the ratio of chemical to eddy lifetime, embodied in the Karlovitz stretch factor, suggested a dimensionless flame height might be expressed by appropriate dimensionless groups involving physico-chemical parameters. This proved to be possible and all the experimental results for the three gases, over a wide range of pressure, can be represented by a single equation.

Keywords: Jet flame, Flame height, Chocked flow.

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