National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Cryogenic He experiment on Natural Turbulent Convection
Králík, Tomáš ; Urban, Pavel ; Musilová, Věra ; Hanzelka, Pavel ; Srnka, Aleš ; Repisky, Andrej
Cryogenic helium gas is a suitable fluid for study of natural turbulent convection at very high Rayleigh numbers. We present experimental method and new result on Reynolds and Péclet numbers characterizing large scale circulation (LSC) of fluid at Rayleigh numbers within the range from 1011 to 1015. Observation of LSC is based on measurement of local temperature fluctuations of convecting helium. For experiments we used a specially designed cylindrical cell of height L = 0.3 m and diameter D = 0.3 m with minimized parasitic effects on studied convection, previously published on CryoPrague 2006 [1].
Radiative Heat Transfer at Low Temperatures over Microscopic Distances in Vacuum
Králík, Tomáš ; Musilová, Věra ; Hanzelka, Pavel ; Horák, Michal ; Srnka, Aleš
We present experimental results on heat transfer between plane parallel surfaces of samples separated with microscopic vacuum gap. Radiative heat flux between metallic samples exceeding 50 times heat flux between black surfaces was observed for gaps of several micrometres at temperatures below 50 K. Comparison with near field theory of radiative heat transfer is presented.

Interested in being notified about new results for this query?
Subscribe to the RSS feed.