Течение гелия-II в канале с пористой вставкой при безвихревом сверхтекучем движении

Abstract

The heat and mass transfer processes associated with flow of superfluid helium (He-II) in a channel filled with porous medium in a certain part of its length are analyzed. The heat flux is directed along the channel axis so that a vapor plug is generated near the heater. The steady-state heat-and-mass transfer processes at the interfaces are calculated using the molecular kinetic theory methods. The motion of He-II in pores is described by equations that take into account the specific features of heat and mass transfer in a quantum fluid. A map of flow modes for normal and superfluid components for a monodisperse porous fill is plotted. The normal component’s laminar and turbulent flow modes for nonvortex superfluid motion are considered. Formulas correlating the porous insert length with the fluid velocity are derived for these modes. It is found that He-II flow toward the heater is possible when the porous insert length exceeds a certain value. The dependences of this reversible length on the porous fill structural features and heat flux density are presented. For the laminar mode of normal motion, the reversible length is determined by the diameter of monodisperse fill particles at a given temperature, whereas in the turbulent mode this length also depends on the heat flux. The influence of liquid temperature is studied. Reversible length calculation examples are given. The results of the performed calculations are analyzed by comparing them with the previously obtained data for He-II flow in a single capillary.