Heat transfer enhancement on thin wires in superfluid helium forced flows

TL;DR

This study demonstrates that heated wires can effectively measure local turbulent flow velocities in superfluid helium, showing heat transfer enhancement similar to classical fluids, challenging previous assumptions about sensor limitations.

Contribution

First experimental evidence of heat transfer enhancement on thin wires in turbulent superfluid helium flows and validation of hot-wire sensors for velocity measurement in such conditions.

Findings

Heat transfer from wires increases with turbulent flow in superfluid helium.

Hot-wire sensors can be used to measure local velocities in superfluid helium.

Cooling behavior scales similarly to classical fluids.

Abstract

In this paper, we report the first evidence of an enhancement of the heat transfer from a heated wire by an external turbulent flow of superfluid helium. We used a standard Pt-Rh hot-wire anemometer and overheat it up to 21 K in a pressurized liquid helium turbulent round jet at temperatures between 1.9 K and 2.12 K. The null-velocity response of the sensor can be satisfactorily modeled by the counter flow mechanism while the extra cooling produced by the forced convection is found to scale similarly as the corresponding extra cooling in classical fluids. We propose a preliminary analysis of the response of the sensor and show that -contrary to a common assumption- such sensor can be used to probe local velocity in turbulent superfluid helium.