Observations of Perfect Potential Flow and Critical Velocities in Superfluid Helium ll

Citation

Craig, Paul Palmer (1959) Observations of Perfect Potential Flow and Critical Velocities in Superfluid Helium ll. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/AA2G-EP61. https://resolver.caltech.edu/CaltechETD:etd-02022006-081545

Abstract

The lift on an airfoil placed in a velocity field of pure superfluid has been found to vanish (i.e., to be at least two orders of magnitude less than the classically expected value) for sufficiently low flow velocities. This result indicates that superfluid helium II can undergo pure potential flow without dissipation. The classical viscosity boundary condition at the trailing edge (Kuta condition) does not apply. Above a (temperature dependent) critical velocity, lift appears. However, even at the highest velocities obtained the observed lift lies far below that expected classically. The critical velocity found from this experiment rises near the lambda point in qualitative agreement with comparable experiments, but fails to show agreement in certain other respects. A "superfluid wind tunnel" capable of developing the required flow is described.

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