Transition to turbulent heat transfer in heated vertical channel - Experimental analysis

Christophe Daverat (1) , Yiqin Li (2, 1) , Hervé Pabiou (1) , Christophe Ménézo (3, 1) , Shihe Xin (1)

1 CETHIL - Centre d'Energétique et de Thermique de Lyon
2 ADEME - Agence de l'Environnement et de la Maîtrise de l'Energie
3 LOCIE - LabOratoire proCédés énergIe bâtimEnt

This experimental study deals with natural convection flow in a water channel with a symmetrical isoflux wall heating. Wall temperature, velocity, bulk temperature and fluctuating quantities are measured for a modified Rayleigh number Ra *=6.7x10^7. The analysis of the mean values shows a change of behaviour at the two-third of the height of the channel. This change turns out to be a transition from a laminar heat transfer in the bottom part of the channel to a turbulent one in the upper part. Due to isoflux wall boundary conditions, shear layers develop and thicken in each half-channel. It is shown that the meeting of these layers at the centre of the channel triggers the transition from a laminar heat transfer to a turbulent one. This experimental study is followed by a scaling analysis.

Mots clés: Turbulent heat transfer; Natural convection; Vertical open channel; Shear layer; vertical open; channel

Domaines: Thermique [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Christophe Daverat, Yiqin Li, Hervé Pabiou, Christophe Ménézo, Shihe Xin. Transition to turbulent heat transfer in heated vertical channel - Experimental analysis. International Journal of Thermal Sciences, 2017, 111, pp.321-329. ⟨10.1016/j.ijthermalsci.2016.09.004⟩. ⟨hal-01393834v2⟩