NUMERICAL STUDY OF FLOW AND HEAT TRANSFER IN CONFINED AND UNCONFINED ROUND MIST IMPINGING JET

The work presents results of numerical investigation of flow structure and heat transfer of unconfined and confined impact mist jets with low mass fraction of droplets (M-L1 <= 1 %). The downward gas-droplets jet is issued from a pipe and strikes into the center of the circular target wall. Mathematical model is based on the solution to RANS equations for the two-phase flow in Euler approximation. For the calculation of the fluctuation characteristics of the dispersed phase model equations of Derevich and Zaichik [1] and Zaichik et al. [2] were applied. Predictions were performed for the distances between the nozzle and the target plate x/(2R)=0.5-10 and the initial droplets size (d(1)=5-100 mu m) at the fixed Reynolds number based on the nozzle diameter, Re=26600. Addition of droplets causes significant increase of heat transfer intensity in the vicinity of the jet stagnation point compared with the one-phase air impact jet.