EXPERIMENTAL AND NUMERICAL STUDY OF A WATER SPRAY IN THE WAKE OF AN AXISYMMETRICAL BLUFF-BODY

An experimental and numerical study was made of a water spray issuing into a recirculating flow behind a bluff body disk mounted in a nozzle . A two-component laser-Doppler/phase-Doppler anomometry system was us ed to characterize the mean and turbulent dispersed phase. The numeric al prediction of the hollow-cone spray was based on an Eulerian-Lagran gian stochastic hybrid model. The continuous gas flow field was predic ted using a differential Reynolds stress transport model whereas the p articulate droplet flow field was predicted using an improved Lagrangi an stochastic dispersion model. Comparison of numerical predictions an d experimental measurements was carried out for droplet mean and fluct uating velocities, number mean diameters, and mass fluxes. Results ind icate that the droplet dispersion characteristics are strongly influen ced by the presence of flow recirculation due to different particle St okes numbers, yielding recirculation or penetration of particles throu gh the separated flow region. Predictions of droplet axial and radial rms velocities obtained with the Lagrangian stochastic model are less satisfactory than those of other simple gas spray flows.