Date of Award

Fall 1975

Document Type

Dissertation - Restricted

Degree Name

Doctor of Philosophy (PhD)


Electrical and Computer Engineering

First Advisor

Linehan, J. H.

Second Advisor

Richardson, B. L.

Third Advisor

Niederjohn, R. J.


One form of the sputtering phenomena, that heat transfer process which occurs when an initially hot vertical surface is cooled by a falling liquid film, was examined from a new experimental approach. The sputtering front. is the lowest wetted position on the vertical surface and is characterized by a short region of intense nucleate boiling. The sputtering front progresses downward at nearly a constant rate with the surface below the sputtering front being dry and almost adiabatic. This heat transfer process is of current interest in the analysis of some of the performance aspects of light water reactor emergency core cooling systems. An experimental apparatus was constructed which enabled the detailed examination of the heat transfer characteristics of a sputtering front. In the present study, a heat source of sufficient intensity was located immediately below the sputtering front which prevented its downward progress thus permitting detailed steady state surface temperature measurements throughout a sputtering front. Experimental evidence was obtained which showed the sputtering front to correspond to a critical heat flux phenomena (CHF). These data were obtained with water flow rates from 350 to 1600 1bm/hr/ft and subcoolings from 40 to 140°F on a 3/8 in. solid copper rod at one atmosphere. A two-dimensional analytical model has been developed to describe a stationary sputtering front where the wet-dry interface corresponds to a CHF phenomena and the dry zone is adiabatic. This model is non-linear because of the temperature dependence-of the heat transfer coefficient in the wetted region and has yield good agreement with data. A simplified one-dimensional approximation is also developed which adequately describes these data. Finally by means of a coordinate transformation and additional simplifying assumptions, this analysis is extended to analyze moving sputtering fronts where reasonably good agreement with reported-data is shown.



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