Turbulent thermal convection of He gas at cryogenic temperatures
Srnka A, Hanzelka P, Musilova P, Urban P (Institute of Scientific Instruments ASCR, Brno)
Skrbek L (Faculty of Mathematics and Physics, Charles University, Praha)
Turbulence: unsolved problem in physics, important in practice, difficulties with numerical simulations.
Experiments under stable laboratory conditions are of great importance.
Ubiquitous turbulent convection: in a horizontal layer of a fluid heated at the bottom and cooled at the top (Rayleigh-Benard convection).
Control parameters are Rayleigh number, Prandtl number, Nusselt number, cell aspect ratio.
Experiments: relations among Ra, Pr, Nu and aspect ratio are examined.
He gas near critical point: tuneable and well known properties, enables study over an unprecedented range of Ra
 Helium cryostat for the study of turbulent thermal convection at cryogenic temperatures |
 Helium cryostat |
 Cylindrical convection cell Ra = up to 1015 (for G = 1) variable aspect ratio G from 1 to 3 The design is focused on precise boundary conditions for the working fluid – helium gas: uniform temperature distribution over entire top and bottom plates and high insulation capability of the side wall. |
 Convection cell |