Numerical Investigation of Water Droplet Impact on Solid Surface in Microgravity

Abstract

A numerical study based on VOF model has been carried out to investigate the dynamics of water droplet impact on solid surface in microgravity in comparison with that in normal gravity to discuss the differences of the extinguishing mechanism of water mist in different gravity level. Water droplets with different initial diameters and impact velocities were considered. The simulated results show that the deformation process in microgravity lags behind that in normal gravity. And it was also found that Dmaxand spread velocities are smaller in microgravity as the potential energy decreases and the time taken for a liquid droplet to reach its maximum spread has no obvious regularity. Hence, the effect of cooling the fuel surface and diluting fuel vapour with water mist in microgravity may be not as good as that in normal gravity.The critical impact Weber number for water droplet breaking up in microgravity is lower than that in normal gravity as the reduction of the value of Bond number, which may result in diluting fuel vapour with water mist in microgravity being more effective than that in normal gravity in some case.

Cavity deformation and bubble entrapment during the impact of droplets on a liquid pool

“…The impact of droplets at high environmental pressure is crucial to many relevant applications, such as fuel atomization in internal combustion engines 42,43 and the droplet impact in nuclear power plants [44][45][46] . In addition, the impact of droplets at low gravity is also important to many relevant applications, such as spray cooling in moving systems and fire extinguishing in spacecraft 47,48 . The effect of the environmental pressure has been proved to be very important during the impact of droplets on solid surfaces 49,50 .…”