TSF EXPERIMENT FOR COMPARISON OF HlGH REYNOLDS NUMBER TURBULENCE IN BOTH HE I AND HE II: FIRST RESULTS

Superfluid turbulence (TSF) project uses liquid helium for the fundamental study of turbulent phenomena behind a passive grid and is able to work both in HeI and in HeII. The helium flow is generated by a cold Barber and Nichols circulating pump, whereas helium flow temperature is kept constant by means of a heat exchanger immersed in a saturated bath. This experiment takes profit of the CEA Grenoble refrigerator (nominal capacity of 400 Watt at 1.8 K) to remove the heat due to pressure losses in this high Reynolds number experiment. In order to resolve the Kolmogorov scale associated with high Re flow, local instrumentation (e.g. sub-micrometer anemometer) was developed. The difficulties encountered with this local and fragile instrumentation in a quasi industrial environment are discussed and the adopted solutions are also described. Finally, first results (permanent mass flow rate of a few hundreds g/s) obtained both in the two phases of helium are presented.