Abstract:
In this experimental study, the Reynolds number limits of
the transitional flow regime and friction factor characteristics
were determined in the transitional flow regime of annuli.
Isothermal and diabatic tests were conducted using four
horizontal concentric annular passages with hydraulic diameters
of 26.2, 23, 20.2 and 17 mm and respective diameter ratios of
0.327, 0.409, 0.386 and 0.483. The water in the annular passage
was either heated or cooled at non-uniform temperature on the
inner wall while the outer wall was insulated. The flow was both
hydrodynamic and thermally developing, and the transitional
flow was associated with mixed convection. The geometric size
of the annular passage had a significant influence on the friction
factors and Reynolds number span of the transitional flow
regime. The annular geometric parameter that represent the
geometric size of the annular passage was proposed and found
to describe the friction factors well. Subsequently, correlations
for predicting the friction factors in the transitional flow regime
were developed.
Description:
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .
