Experimental study on the refined thermal-hydraulics of a sodium flow across a tube row

This paper presents experimental results obtained in an in-sodium mock-up, made of 30 electrically heated tubes, devoted to the analysis of heat transfer and temperature fluctuations. Three parameters have been studied: mean temperature level (from 350 deg C to 470 deg C), REYNOLDS number (6600 to 63000) and heat flux density (100 to 600 kW/m2). The mean temperature field is quite homogeneous, due to the strong conduction. High temperature fluctuations are noticed. These fluctuations increase with the heat flux. They are lower and with a gaussian Density Probability Function for the lowest and the highest REYNOLDS number values. They are higher (with a maximum peak-to-peak value of 70 deg C) for REYNOLDS numbers around 9000; for this value, the spectra contains a periodic component (with a STROUHAL number equal to 0.3), and the distribution can have either a gaussian, or a ''double peak'', or an intermediate shape. (authors). 11 figs., 16 refs