Electric field modulated rebound suppression during high velocity droplet impact on a heated surface

Droplet rebound suppression can improve spray cooling by extending the time the liquid interacts with the heated wall and reducing energy loss. The electrowetting (EW) technique may control droplet impingement to improve spray cooling by modulating the impact dynamics. This work investigates the integration of the EW technique with impact dynamics on a heated surface and its potential to augment heat dissipation. In this regard, a numerical model is developed using the phase-field method and a molecular-kinetic-theory-based dynamic contact angle model. First, we have verified the accuracy of our numerical model with the experimental results. The present study investigates the impact dynamics under various contact angles ( θ s , 0 ) and Weber numbers ( We ), and a corresponding regime map is generated to analyse the behaviour of droplet impact. Later, droplet impact dynamics is integrated with electrowetting, revealing complete or partial rebound suppression depending on the We and contact angle conditions. It has been observed that EW-assisted droplet impact shows complete rebound suppression at impact velocities of 0.3 to 2.5 m/s, corresponding to We ranging from 3.2 to 221.4 and contact angles of 100° to 140°, in contrast to the case without EW. The EW assisted cooling effectiveness ( ε E W ) for We = 3.2 for θ s , 0 of 160° is 17.6 times that of the case without EW. Moreover, ε E W increases by 141.5% and 104.2% for θ s , 0 of 100° to 160° at a lower We of 12.7. However, it increases by 59.5% and 29.8% respectively with a higher We of 221.4.