Effect of droplet evaporation on the flow structure and heat and mass transfer in a confined swirling gas-droplet flow downstream of a tube sudden expansion

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The effect of flow swirl parameter and thermophysical properties of the droplet of water, ethanol, and acetone on the structure of turbulent flow and heat transfer in a gas-droplet flow was studied numerically. To describe the dynamics and heat and mass transfer of the two-phase flow, the Eulerian approach was used. The growth of the volume fraction of small particles on the tube axis is typical of a swirling flow because of their accumulation in the zone of reverse flows due to the turbophoresis force. It is shown that the addition of droplets leads to a signifi-cant increase in heat transfer (more than 2.5 times) at mass concentration of droplets M_L1 = 0.1 in comparison with a single-phase swirling flow. Intensification of heat transfer with the use of ethanol droplets is higher than that for water droplets (approximately 10–20 %) and acetone (up to 65 %). When using the droplets of ethanol and acetone, the region of two-phase flow existence reduces, and the degree of suppression of carrier phase turbulence decreases. This is due to a more rapid evaporation of droplets of volatile liquids.