A cryogenic-helium pipe flow facility with unique double-line molecular tagging velocimetry capability

Abstract

Cryogenic helium-4 has extremely small kinetic viscosity, which makes it a promising material for high Reynolds ($Re$) number turbulence research in compact laboratory apparatuses. In its superfluid phase (He II), helium has an extraordinary heat transfer capability and has been utilized in various scientific and engineering applications. In order to unlock the full potential of helium in turbulence research and to improve our understanding of the heat transfer mechanism in He II, a flow facility that allows quantitative study of helium heat-and-mass transfer processes is needed. Here we report our work in assembling and testing a unique helium pipe flow facility that incorporates a novel double-line molecular tracking velocimetry (DL-MTV) system. This flow facility allows us to generate turbulent pipe flows with $Re$ above $10^7$, and it can also be adapted to produce heat-induced counterflow in He II. The DL-MTV system, which is based on the generation and tracking of two parallel thin He${}_2^{\ast }$ molecular tracer lines with an adjustable separation distance, allows us to measure not only the velocity profile but also both the transverse and longitudinal spatial velocity structure functions. We have also installed a deferential pressure sensor to the flow pipe for pressure drop measurement. The testing results of the flow facility and the measurement devices are presented. We discuss how this facility will allow us to solve some outstanding problems in the helium heat-and-mass transfer topic area.

arXiv comment9 pages, 11 figures

References in corpus (16)

• Visualization study of counterflow in superfluid helium-4 using metastable helium molecules
• Visualization of the normal-fluid turbulence in counterflowing superfluid 4He
• Coherent vortex structures in quantum turbulence
• Metastable helium molecules as tracers in superfluid liquid ${}^4$He
• Excimers He2* as Tracers of Quantum Turbulence in 4He in the T=0 Limit
• Different intermittency for longitudinal and transversal turbulent fluctuations
• A superfluid boundary layer
• Dissipation in quantum turbulence in superfluid ${}^4$He above 1K
• Determination of the effective kinematic viscosity for the decay of quasiclassical turbulence in superfluid ${}^4$He
• Intermittency enhancement in quantum turbulence
• ${}^4$He Counterflow Differs Strongly from Classical Flows: Anisotropy on Small Scales
• Statistics of turbulence and intermittency enhancement in superfluid ${}^4$He counterflow
• Observation of Crossover from Ballistic to Diffusion Regime for Excimer Molecules in Superfluid ${}^4$He
• Studying the normal-fluid flow in Helium-II using metastable helium molecules
• Molecular Tagging Velocimetry in Superfluid Helium-4: Progress, Issues, and Future Development
• Shape fluctuations and optical transition of He${}_2^{\ast }$ excimer tracers in superfluid ${}^4$He