F204 CHARACTERISCTICS OF EVAPORATING DROPLETS DISPERSION SUSPENDED IN ISOTROPIC TURBULENCE(DNS and computational procedure for turbulence)

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The characteristics of two-phase turbulent heat and mass transport in water-droplets suspension in a gas flow were investigated by direct numerical simulations in decaying isotropic turbulence. Velocity and temperature fields were solved by the pseudospectral method with 64^3 grid points. The behavior of 32,768 droplets was time advanced using the motion, energy and mass-transfer-rate equations. Droplets had an increasing tendency to accumulate in region of low vorticity due to a decrease in droplet diameter. Large temperature fluctuation of droplets induced high vaporization rate. The magnitude of latent heat of evaporation affected significantly temperature-fluctuation variances of droplets and decreased rapidly the Lagrangian autocorrelation coefficient of droplet temperature, yielding decreasing the mass transfer rate from droplets due to phase change. The enthalpy transport was controlled mainly by the intense regions of the scalar gradient, induced by a persistent straining field of the vortex structures which affect the preferential concentration of droplets.
一般社団法人日本機械学会の論文
2000-10-01