HEAT TRANSFER OF A TURBULENT WATER FILM AT DIFFERENT INITIAL FLOW CONDITIONS AND HIGH TEMPERATURE GRADIENTS
Shear stress at the wall, velocity fields and heat transfer were measured in the initial part of a turbulent film-flow of water under different initial flow conditions. Lengths of the region of a stabilization both flow dynamics and heat transfer are determined, calculation techniques are suggested for the transient friction drag and heat transfer in the initial part of a turbulent film. Heat transfer with high temperature gradients was also measured in a turbulent film. The results were used in determining the effects of variable physical properties on the heat transfer in a non-boiling film, and in determining the effects of the heat flux density, degree of underheating and wetting density on the heat transfer in a turbulent film with local nucleate boiling. Peak heat flux values were determined as functions of the degree of underheating and of wetting density, to find application limits of turbulent water films as coolers of surfaces of high heat emittance.