Dr gang zhou (Technical Institute of Physics and Chemistry, CAS)
A numerical study is performed for time-varying natural convection of helium fluid at low temperatures in a bottom wall heated cylinder enclosure. The numerical results are analyzed in detail to show the damping of the temperature fluctuation amplitude from the cold up wall to the hot down wall, which is characterized by the ratio of the fluctuation amplitude of down wall and up wall. Fluid flow field, thermal field and heat transfer are analyzed for some particular situations through the streamlines and isotherms. Based on the simulation results, the effects of thermal conductivity of walls and inclined angles of the enclosure on the damping of temperature fluctuation amplitude are studied. Numerical computations provide methods of decaying the propagation of the fluctuation amplitude through the fluid and wall, which have great importance in high precision temperature control at low temperature system cooled by cryocooler.
Dr Kongrong Li (Technical Institute of Physics and Chemistry,CAS)