R. Zanino et al., Friction factor correlation with application to the central cooling channel of cable-in-conduit super-conductors for fusion magnets, IEEE APPL S, 10(1), 2000, pp. 1066-1069
A correlation has been developed for the turbulent friction factor f of a c
ircular channel with a helical rib roughness of rectangular cross section,
which is relevant to the central channel (hole) in two-channel cable-in-con
duit conductors. The correlation is based on data we measured on a pipe wit
h three different types of helix. It relates f with the Reynolds number Re
and with suitable dimensionless combinations of all relevant geometrical pa
rameters of the problem, i.e., hole diameter and helix gap and thickness. A
limited comparison with actual (QUELL) conductor data shows good agreement
.