Prediction of turbulent flow characteristics and heat transfer in a dilute droplet-laden flow over a backward-facing step

Abstract

We present numerical investigation of the influence of the thermophysical properties of droplets on turbulence modification, scattering of droplets, and heat transfer augmentation in a two-phase mist flow over a backward-facing step. Predictions are made for droplets of water, ethanol, acetone, and glycerol, with droplet diameters in the range d₁ =1–100 μm and mass fractions in the range M_L1=0.01–0.1 at the inlet. The RANS approach is used to simulate the gaseous phase, and the motion and heat transfer of the dispersed phase are computed using Eulerian model. Carrier phase turbulence is predicted using a second moment closure model. The effect of attenuation of the gas phase turbulent kinetic energy is shown to be minimal for acetone droplets (more than 7%), whereas the largest effects are seen for glycerol and water droplets (up to 15%). Heat transfer enhancement is shown to reach a maximal value with the use of ethanol (more than twice as high as for single-phase flow over the backward-facing step), while minimal intensification is obtained for the evaporation of acetone droplets (up to 25%).

Keywords:

• Droplet-laden mist flow
• droplets dispersion and evaporation
• Eulerian modeling
• heat transfer enhancement
• single-side rearward-facing step
• thermophysical properties
• turbulence modification

Additional information

Funding

This work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (mega-grant 075-15-2021-575). The RANS and turbulence model for the single-phase flow were developed under the state contract with IT SB RAS (121031800217-8).