Abstract
Superfluid helium (He II) is a unique fluid having many characteristic features different from those of ordinary fluids. Film boiling in saturated He II in earth gravity is strongly affected by the sub-cooling due to a small hydrodynamic pressure. In this study, microgravity experiments with He II were conducted using a drop tower, because zero sub-cooling can be realized in microgravity. The experimental study confirmed that the critical heat flux in He II in microgravity was subjected to the influence of the van der Waals force. Owing to the extremely high effective thermal conductivity of He II, the effect of the van der Waals force on the critical heat flux in microgravity became notable, although this effect did not appear at all in any ordinary fluids. Comparison of the critical heat flux in normal liquid helium (He I) with the previously reported results of Straub’s experiments, which is compared the extended Zuber’s relation, confirmed that the result of He I agreed with the correlation derived from the surface tension and buoyancy but the result of He II disagreed with it.
