| Abstract: | We study the dynamics of heat and mass transfer through a water-air interface on the basis of laboratory radiometric measurements
of the time dependence of thermal radio emission of water at a frequency of 60 GHz, which is related to air turbulization
above its surface by a fan. We recover the dynamics for the temperature profile in water and in a viscous sublayer of air
as well as for the heat flux through the water-air interface. The flux components related to evaporation and heat exchange
and the rate of evaporation from a unit surface are determined. An equation for determining the thickness of the viscous sublayer
in the air from the heat flux value is obtained;this thickness is about 2 mm under the experimental conditions. The process
dependence on the water turbulence is established and methods for determining the thermal film thickness are proposed. In
the absence of turbulence in unstable stratified water we observed the development of a periodic convective process from the
time the critical value of the Rayleigh number was reached. The heat exchange dependence on the presence of petroleum film
on the water surface is studied. It is found that for a film thickness of 5 μm the heat exchange rate decreases by a factor
of 3 because of the petroleum presence.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 40, No. 3, pp. 351–369, March, 1997. |
