Abstract
We present preliminary results of the visualization of a submerged coflow jet of liquid helium produced by a fountain pump. The jet propagating inside the bulk superfluid is visualized with particle tracking velocimetry using hydrogen particles.
We compare the characteristics of the coflow jet with those measured in classical fluids such as helium gas or water. In contrast to the classical experiments, a temperature-dependent angle of the jet is observed, suggesting that the flow may not be described quasi-classically, despite the strong coupling between normal and superfluid components by mutual friction.
We report on the statistics of the velocities inferred from the particle trajectories recorded by a high-speed camera at 1.68 and 1.95K, for jet velocities ranging from 47 to 4500mm/s.