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The Origin of Turbulence Acquired by Heavy Particles in a round, turbulent jet
Author(s) -
Mastorakos Epamidas,
McGuirk James J.,
Taylor Alexander M. K. P.
Publication year - 1990
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.19900070134
Subject(s) - turbulence , particle (ecology) , mechanics , jet (fluid) , physics , k epsilon turbulence model , stokes number , nozzle , k omega turbulence model , turbulence kinetic energy , classical mechanics , thermodynamics , reynolds number , geology , oceanography
The paper describes the application of a stochastic separated flow model for the dispersed phase to the prediction of a particle‐laden turbulent air jet discharging at 13 m/s from a 15 mm nozzle into stagnant surroundings. Emphasis is placed on the stochastic element of the Lagrangian particle tracking part of the model and on the importance of particle initial conditions over the first 20 jet diameters. Calculations are presented for 80 m̈m sized glass particles which clarify how particles with turbulent Stokes number less than unity acquire axial turbulence much larger than radial. Far from being only a response to the gas‐phase turbulence as implied by the model, the axial turbulence is shown to be also produced by an interaction between particle radial turbulence fluctuations and cross‐stream spatial gradients in particle mean velocity, here referred to as "fanspreading". In addition, initial particle turbulence levels remain identifiable for about 10 jet diameters; the initial radial turbulence reinforces the fan‐spreading contribution and leads to extra generation of axial turbulence farther downstream. In general, the results agree well with experimental measurements.