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Measurements of entrainment by axisymmetrical turbulent jets

Published online by Cambridge University Press:  28 March 2006

F. P. Ricou
Affiliation:
Mechanical Engineering Department, Imperial College of Science and Technology, London, S.W. 7
D. B. Spalding
Affiliation:
Mechanical Engineering Department, Imperial College of Science and Technology, London, S.W. 7

Abstract

A new technique is described for measuring the axial mass flow rate in the turbulent jet formed when a gas in injected into a reservoir of stagnant air at uniform pressure. The jet is surrounded by a porous-walled cylindrical chamber, and air is injected through the wall until the pressure in the chamber is uniform and atmospheric, a condition which is taken to signify that the ‘entrainment appetite’ of the jet is satisfied.

Measurements made with the apparatus have allowed the deduction of an entrainment law relating mass flow rate, jet momentum, axial distance and air density, regardless of the injected gas, and including the effects of buoyancy. When the injected gas burns in the jet the entrainment rate is up to 30% lower than when it does not.

Type
Research Article
Copyright
© 1961 Cambridge University Press

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