Modelling of small droplets heating and evaporation

  • Sazhin, Sergei (PI)
  • Gusev, Ivan (CoI)
  • Heikal, Morgan (CoI)
  • Lemoine , Fabrice (PI)

Project Details


This research involved the study of droplet transient heat conduction equation in the presence of evaporation (moving boundary effects) using analytical techniques.

This equation was solved using two different methods. Firstly the solution was presented in the integral form. This would eventually allow researchers to reduce the solution of the differential equation for droplets to the solution of the Volterra type integral equation. The second approach was based on the presentation of the solution in the form of converging series.

These solutions were be applicable for arbitrary droplets, but the effects they described would be particularly important for small droplets when the changes of their radii during the time step are comparable with the values of their radii.

The project would investigate the applicability of both these solutions into the customised in-house version of the KIVA-2 CFD code. At least one of these solutions would be implemented into this code. The applicability of the previously obtained analytical solution for transient heating of a spherical body for implementation into the new version of the KIVA-2 code will be investigated. It is expected that this implementation will be possible at least in some limited cases (small droplets).

Key findings

The results of a series of experiments focused on investigation of the heating and evaporation of suspended water droplets in a hot air flow (at temperatures up to 800 C) are described.

The temperatures inside droplets were estimated based on Planar Laser-Induced Fluorescence (PLIF) imaging. The advantages and limitations of this method are investigated. Typical distributions of temperatures inside droplets at the initial stages of their heating and evaporation are presented. These distributions at various cross-sections are compared. They are shown to be strongly inhomogeneous during the whole period of observation.

A new model for heating and evaporation of a suspended droplet, taking into account temperature gradient and recirculation inside the droplet and the effect of a supporting rod, is suggested. It is assumed that the heat transferred from the rod to the suspended droplet is homogeneously distributed inside the droplet; its effect is modelled similarly to the effect of external thermal radiation, using the previously developed model for droplet heating in the presence of this radiation.

It is shown that a reasonable agreement between the model predictions and experimental data can be achieved if the reduction of the ambient gas temperature due to the presence of an evaporating droplet is taken into account. The effect of the rod on droplet heating is shown to be most significant for ambient gas temperature equal to 100 C and becomes negligibly small when the gas temperature reaches 800 C.
Effective start/end date1/01/1431/12/17


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