Experimental study of thermo-fluid dynamic effect in He II cavitating flow

We have conducted a series of experiments of superfluid helium (He II) cavitating flow driven by a bellows pump by applying flow visualization method and PIV (Particle Image Velocimeter), and through the measurements of the temperature and the pressure depressions. In this study the experimental results were examined in particular focusing on the thermodynamic effect by referring to the thermodynamic parameter Σ introduced by Brennen. It is found that the thermodynamic effect is negligible in cavitating flows of He II with small void fraction, in accordance with the Σ prediction. On the other hand, in the case of large void fraction the magnitude of the temperature depression is finite and there is apparent temperature dependence in its variation. These features indicate that He II also behaves as a cryogenic fluid in cavitating flow, in which the thermodynamic effect is noticeable.

► Superfluid He II cavitating flow was driven by a bellows pump. Flow visualization and PIV were applied together with the temperature measurement.
► Thermodynamic effect in He II cavitating flow was investigated.
► Thermodynamic effect in He II is mostly negligible owing to superthermal conduction.
► He II flow is accompanied by thermodynamic effect in the case of large void fraction.