Introduction

Background

Objectives


Test facility

Measurement techniques


Disintegration regimes

Secondary atomization within the various boiling regimes

Boiling morphology at liquid-solid interface

Heat transfer and droplet dynamics on surface enhanced surfaces






 

 
Dynamics of impacting droplets

micro nano engineering
   

  Secondary atomization within the various boiling regimes

In this part of the work, image analysis techniques are combined with measurements using a phase Doppler instrument to quantify the effect of different parameters, namely liquid properties, impact angle and surface topography, in secondary droplet characteristics. Combination of both techniques allows studying the temporal evolution of secondary droplet size and velocity distributions over extended distributions, within a wide range of droplet diameters, from 5mm up to few millimetres, thus covering the various boiling regimes. The figure illustrates the SMD evaluated from the extended pdf’s of the secondary droplets resulting from the impact of water and isooctane drops onto a stainless steel surface at similar conditions, within the nucleate and film boiling regimes. The SMD is evaluated from the extended size distributions obtained with the combination of phase Doppler measurements and image analysis, for various time instants and different impact angles, a.

Bubble Boiling



Film Boiling



This study is performed in collaboration with the Thermofuids and Heat Transfer Group – THT from the Engineering Faculty of Bergamo University.