Turbulent convective heat transfer in an inclined tube filled with sodium

Abstract

Turbulent free convection of liquid sodium in a straight thermally insulated tube with a length equal to 20 diameters and with end heat exchangers ensuring a fixed temperature drop is investigated exper imentally. The experiments are performed for a fixed Rayleigh number Ra = 2.4 × 10 6 and various angles of inclination of the tube relative to the vertical. A strong dependence of the power transferred along the tube on the angle of inclination is revealed: the Nusselt number in the angular range under investigation changes by an order of magnitude with a maximum at the angle of 65° with the vertical. The characteristics of large scale circulation and turbulent temperature pulsations show that convective heat transfer is mainly determined by the velocity of large scale circulation of sodium. Turbulent pulsations are maximal for small angles of incli nation (α = 20°-30°) and reduce the heat flux along the channel, although in the limit of small angles (ver tical tube), there is no large scale circulation, and the convective heat flux, which is an order of magnitude larger than the molecular heat flux, is ensured only by small scale (turbulent) flow.

Turbulent convection for different thermal boundary conditions at the plates

“…Results obtained in an experimental apparatus of same geometry by Vasil'ev et al. (2015) yielded an increase of the convective heat flux from to . Our findings are thus also consistent with previous liquid metal flow investigations, both experimental and numerical ones.…”

Thermal convection in inclined cylindrical containers

“…As discussed, for large Ra we expect a monotonic reduction of Nu with increasing β for large Pr, as in the experiments by Guo et al (2015), and a single maximum for an intermediate value of β in the Nu versus β dependence for the case of small Pr, as obtained in the measurements by Langebach & Haberstroh (2014), Frick et al (2015), Kolesnichenko et al (2015) and Vasilev et al (2015). Further investigations of inclined convection in different fluids, both experimentally and numerically, for large and small Pr, are required for a better understanding of the mechanisms driving inclined convection and their Re(β)-and Nu(β)-dependences.…”

“…Such measurements in liquid sodium, Pr ∼ 0.01, are reported by Frick et al (2015), Kolesnichenko et al (2015) and Vasilev et al (2015). Moreover, these experiments show that, in the case of small Pr (Pr 1) and relatively large Ra (Ra 10 9 ), any tilt β, 0 < β π/2, of the cell leads to an increase of Nu, compared to that in the RBC case (β = 0).…”

The influence of the cell inclination on the heat transport and large-scale circulation in liquid metal convection

“…the fluid layer between the parallel plates is tilted with respect to the direction of gravity, and both buoyancy and shear act on the flow. This type of convection was studied previously by Daniels, Wiener & Bodenschatz (2003), Chillà et al (2004), Sun, Xi & Xia (2005), Ahlers, Brown & Nikolaenko (2006b), Riedinger et al (2013), Weiss & Ahlers (2013) and Langebach & Haberstroh (2014), and more recently by Frick et al (2015), Mamykin et al (2015), Vasil'ev et al (2015, Kolesnichenko et al (2015), Shishkina & Horn (2016), , Mandrykin & Teimurazov (2019), Khalilov et al (2018) and Zwirner & Shishkina (2018).…”