Phase‐Doppler‐Anemometry and the Log‐Hyperbolic Distribution applied to Liquid Sprays

Abstract The paper provides a description of the local drop‐size distributions in a liquid spray issuing from a 60° oil‐burner nozzle obtained experimentally using a phase‐doppler anemometer. The details of the optical system and the signal processing electronics of the phase‐Doppler anemometer are included. Details have also been given concerning the use of the log‐hyperbolic distribution and in particular of a procedure for determining the four defining parameters from a given experimental distribution, in this case that of drop size. Analytical formulae to compute moments of the distribution and the mean diameters are also given. All size distributions are shown to be well described by the log‐hyperbolic distribution involving four parameters. The variation of these parameters along the axis of the jet clearly reveals a developing region of the spray followed by a fully developed state, for which physical reasons are given. The parameters can also be used to predict the local drop‐size distribution at any intermediate location on the spray axis.