Heat Transfer Enhancement of He II Co-current Two-phase Flow in The Presence of Atomisation

Previous experiments performed on HeII co-current two-phase flow at CEA Grenoble have shown the existence of a transition from stratified two-phase flow to droplet mist flow at high vapour velocities. The realisation of a new refrigerator/liquefier able to produce up to 20 g/s of single phase superfluid helium at 1.8 K (instead of 7 g/s previously) was achieved. Benefit was taken of the necessary junction between the existent test line and the refrigerator to introduce some new instrumentation [1]. Results of preliminary experiments performed on this new configuration are given. The response of liquid level and vapour density on droplet flow is presented. First results on pressure drop obtained for a total mass flow rate of 15 g/s are also presented. Finally, the use of various capacitive level gauges glued at different azimutal positions along the inner pipe give access to the perimeter wetted by a continuous thin liquid film.