Towards sodium combustion modelling with liquid water

TL;DR

This paper develops a diffuse interface flow model to simulate complex sodium-water combustion phenomena, capturing multi-phase interactions, shock waves, and Leidenfrost effects in multidimensional settings.

Contribution

It introduces the first multidimensional simulations of sodium-water combustion using a diffuse interface approach, addressing complex flow dynamics and reaction mechanisms.

Findings

Shock wave emission observed in simulations matches experimental reports.

Sodium drop motion on liquid water surface successfully modeled.

Explosion phenomena qualitatively reproduced with turbulence and delayed ignition.

Abstract

Solid and liquid sodium combustion with liquid water occurs through a thin gas layer where exothermic reactions happen with sodium and water vapors. It thus involves multiple interfaces separating liquid and gas in the presence of surface tension, phase transition and surface reactions. The gas phase reaction involves compressible effects resulting in possible shock wave appearance in both gas and liquid phases. To understand and predict the complexity of sodium combustion with water a diffuse interface flow model is built. This formulation enables flow resolution in multidimension in the presence of complex motion, such as for example Leidenfrost-type thermo-chemical flow. More precisely sodium drop autonomous motion on the liquid surface is computed. Various modelling and numerical issues are present and addressed in the present contribution. In the author's knowledge, the first computed results of such type of combustion phenomenon in multidimensions are presented in this paper thanks to the diffuse interface approach. Explosion phenomenon is addressed as well and is reproduced at least qualitatively thanks to extra ingredients such as turbulent mixing of sodium and water vapors in the gas film and delayed ignition. Shock wave emission from the thermo-chemical Leidenfrost-type flow is observed as reported in related experiments.