Numerical Simulation of Wave Formation and Heat Transfer in Falling Liquid Films at Unsteady Heat Release

Development of Methods for Heat Transfer Enhancement During Nitrogen Boiling to Ensure Stabilization of HTS Devices

“…In this figure, region I features absence of crisis; region II presents the set of the problem parameters with which the liquid film decay will occur at total local evaporation without liquid boiling-up; zone III gives the set of parameters with which the liquid film decay will occur at film boiling-up. The authors [140,144,147] show that the results of the numerical simulations are in satisfactory agreement with the experimental data. The presented regime map makes it possible to determinate the film decay regime depending on the heat flux density and inlet Reynolds number.…”

“…The proposed model allows calculations of the wave characteristics and parameters of liquid film decay at different regime parameters. Dependencies of boiling expectation time and total local evaporation time in falling wavy films of liquid nitrogen on the heat flux density for different inlet Reynolds numbers were calculated by the authors in [140,144,147]. All the calculated dependencies were found out to be approximately similar in the area of high heat flux rates for all examined inlet Reynolds numbers, which indicates weak influence of the irrigation flow rate on the boiling expectation time in this range of heat loads.…”

“…Works of the authors [138][139][140][141][142][143][144][145][146][147][148][149] study regularities of heat transfer during evaporation, boiling, and decay of falling nitrogen films, accompanied by development of crisis phenomena at unsteady heat release and unsteady cooling of strongly overheated bodies by falling nitrogen films. The results of experimental investigations of the dynamics of heat transfer and critical phenomena in falling wavy films of nitrogen at unsteady heat release from the surface of a thin-walled heater are presented in [138,139].…”

“…The authors of the research presented a mathematical model that enables calculation of the wave surface profile and velocity and temperature fields, as well as studying their evolution in falling liquid films with a sharp change in the thermal loads over time [140,144,147]. A numerical simulation of the wave formation and heat transfer intensity was performed for falling films of liquid nitrogen.…”