Study on Quantitative Phase Field Method of Solid-Air Dendrite Growth and Solidification in Liquid Hydrogen

This paper proposes a quantitative phase field model to investigate the evolution of dendrite microstructures and the non-uniform distribution of oxygen solutes during the solid-air dendrite growth and solidification. The model is applied to study the characteristics of single-and multi-dendrite growth behaviour under continuous cooling conditions, and two special position curves arc chosen to quantify the solute distribution law. The results show that the dendrite morphology becomes more complex with intensified initial supercooling, and that the secondary dendrite arms arc more developed. The mass fraction of oxygen solute shows oxygen is poor inside dendrites and rich outside of them and a ridge with a lower oxygen mass fraction is formed along the axis of the primary and secondary dendrite arms. The symmetrical morphology of the dendrites is broken by the interaction of multiple dendrites. Under continuous cooling conditions, the secondary solid-air dendrite arms gradually coarsen and fuse over time, with the solid fraction and maximum oxygen mass fraction showing a continuous increase to a maximum value of 0. 911 1 and 0.840 6 respectively. The gaps between the dendrites impede the diffusion of oxygen solutes, making the oxygen solute mass fraction rise from 0. 402 in a single dendrite to 0. 668 in multiple dendrites. This study can provide theoretical guidance for safety in the use of liquid hydrogen systems.