Atomization and Sprays, Vol.5, No.3, 305-328, 1995
MEASUREMENTS OF MU'(GI)MU'(PI) IN MIXING-LAYER FLOW WITH DROPLET LOADING
Measurements of the turbulence modulation term, u'(gi)u'(pi), between the carrier and dispersed phases from experimental data were performed by a phase Doppler particle analyzer (PDPA) system The cross-correlation function between phases, u'(gi)(t)u'(pi)(t + tau), was first determined from the measured raw data which involved real-time information about velocities and associated drop sizes. The time delay, tau, was selected based on the flow characteristic time. The velocity of 2-mu m drops was taken as that of the carrier phase. The cross-correlation functions for 10-mu m, 20-mu m, and 30-mu m drops were then calculated from the raw data for each size range. The value of the cross-correlation function at tau = 0, that is, the turbulence modulation term, was obtained based on the symmetric property of this function and interpolation of the data. Results show that the turbulence modulation term can be expressed as functions of drop relaxation time, tau(p), turbulence kinetic energies of both phases, kappa and kappa(p), Reynolds stress u'(g) upsilon'(g), and velocity correlation of the drop phase, u'(p) upsilon'(p), instead of the formulation suggested by Pourahmadi and Humphrey [5] as well as by Chen and Wood [3, 4], which considered tau(p) and kappa only. It is suggested that the modeling of spray flow requires a more complete formulation based on the experimental data shown in this article.