Jet vortex heat transfer in turbulent air flow around a plate with a slit rib

Abstract

Experimental study and numerical simulation of vortex heat transfer in turbulent air flow around the plate with permeable transverse rectangular ribs at qw = const have been made. Confusor, diffuser and constant cross-section slits as well as the constant gap between the plate and the lower wall of the rib are considered. Mean and fluctuation profiles of velocity and temperature along the midsection of the plate in the sections of the turbulent boundary layer are measured using both a Pitot–Prandtl microprobe with a microthermocouple and a Dantec Dynamics hot-wire anemometer. To calculate spatial separated flow of incompressible liquids, the Reynolds-averaged Navier–Stokes equations closed by five turbulence models are adopted. The use of the k-ε two-parameter model with the Kato–Lauder modification (SKE-KL) provides a satisfactory agreement between numerical predictions and experimental data. So this model is selected as the basic one. The influence of the throttling effect on the turbulent separated flow structure and relative heat transfer coefficient when changing the slit shape and size is analyzed. The integral characteristics including total heat transfer coefficient, hydraulic losses and thermal-hydraulic performance are also compared. It is shown that the presence of a slit can eliminate secondary separation zones on the plate and decrease recirculation flow regions behind a rib. The rib with a confusor slit has the highest thermal-hydraulic performance that is by 15% more than that of the solid rib.