The effect of flow swirling on flow structure, turbulence and heat transfer in turbulent droplet-laden flow in a pipe sudden expansion

Abstract

This paper presents the mathematical model to simulate the swirling turbulent gas-droplet flow in a sudden pipe expansion. The set of axisymmetrical steady-state RANS equations for the two-phase flow is used. The dispersed phase is modeled by the Eulerian approach. The flow swirl causes an increase in the intensity of heat transfer (more than 1.5 times in comparison with the non-swirling mist flow at other identical inlet conditions). Evaporation of the droplets leads to a significant increase in the heat transfer intensity in the swirling two-phase flow (more than 2.5 times in comparison with the single-phase flow). It is shown that ethanol droplets evaporate much faster than water droplets due to the lower heat of phase transition. The heat transfer enhancement by using ethanol droplets is higher than the corresponding value for water droplets (up to 20%).