Flow dynamics and heat transfer characteristics of air/water mist jet impingement using Eulerian-Eulerian approach

The present numerical study focuses on a two-phase Eulerian-Eulerian approach to model the flow structure and heat transfer characteristics of an air/water mist jet emanating from a coaxial jet nozzle and impinging on an isothermal heated flat plate. A detailed parametric numerical study has been performed to investigate the effect of various operating parameters like air Reynolds number (2400-9142), mist Reynolds number(1.87-8.68), mist loading fraction (0 % - 0.96 %), droplet diameter (1 mu m - 60 mu m), and non-dimensional nozzle to plate spacing (10-42) on the flow structure and heat transfer characteristics of air/water mist jet. The present numerical results are in agreement with the experimental results, within 16 % accuracy. The heat transfer increases with an increase in the air Reynolds number or mist loading fraction. The increase in air Reynolds number provides better heat transfer enhancement as high as 94.5 % compared to 27.6 % in the case of an increment in the mist loading fraction. Additionally, the effect of droplet diameter on the flow structure and heat transfer characteristics of air/ water mist jet is analyzed at depth. The increase in nozzle-to-plate distance from 10 to 42 leads to a decrease in stagnation point Nusselt number of the order of 31 %. Further, correlations have been proposed to predict the Nusselt number at the stagnation point, stagnation region, and average Nusselt number for the target plate.