New results in cryogenic helium flows at ultra-high Reynolds and Rayleigh numbers

Abstract

Liquid helium I, II and cryogenic helium gas are used to generate and study highly turbulent flows under controlled laboratory conditions. These three working fluids have remarkable versatility, allowing extremely large values and dynamic ranges of the Reynolds (Re) and Rayleigh (Ra) numbers to be reached. In particular, cryogenic helium gas has been used to study turbulent thermal convection in a range 106≤Ra≤1017, by far the largest ever attained in a controlled experiment on turbulence. The upper limit exceeds previous studies by nearly three orders of magnitude.