  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$^*_2$ 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.

Other Condensed Matter;Fluid Dynamics;Instrumentation and Detectors