THE EFFECT OF TURBULENCE ON RATES OF PARTICLE FORMATION BY HOMOGENEOUS NUCLEATION

The effect of turbulent mixing on the homogeneous nucleation rate was studied at 400 K injected into dry air at 298 K and 1 atm. To simplify the calculations, it was assumed that the Lewis number was everywhere unity. Probability density functions for the temperature fluctuations in an axisymmetric shear layer were used to calculate the local parti cle formation rate, averaged over the fluctuations, and the resulting particle concentration profile. Taking turbulent fluctuations into acc ount significantly reduces local maxima in the average nucleation rate and broadens the region of particle formation in the shear layer comp ared with calculations based on the mean saturation ratio profile. How ever, the overall rate of particle formation in the mixing layer, taki ng fluctuations into account, is of the same order of magnitude as the rates based on the mean concentration and temperature for the conditi ons of the calculation.