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Mixing of a Cold Liquid Jet With a Boiling Liquid Stream

Description: The turbulent mixing of a cold liquid jet with a stream of vapor bubbles and saturated liquid is analyzed for a single axial liquid jet. The cases where the issuing jet velocity is very much greater than and nearly equal to the free stream velocity are considered. Transport of axial momentum and of scalar quantities in the stream are calculated and the results applied to the transport of enthalpy in a bubbly mixture. (D.L.C.)
Date: October 21, 1960
Creator: Bankoff, S. G.
Partner: UNT Libraries Government Documents Department

Fuel-coolant interaction in a shock tube with initially-established film boiling. [PWR; BWR]

Description: A new mode of thermal interaction has been employed, in which liquid metal is melted in a crucible within a shock tube; the coolant level is raised to overflow the crucible and establish subcooled film boiling with known bulk metal temperature; and a pressure shock is then initiated. With water and lead-tin alloy an initial splash of metal may be obtained after the vapor film has collapsed, due primarily to thermal interaction, followed by a successive cycle of bubble growth and collapse. To obtain large interactions, the interfacial contact temperature must exceed the spontaneous nucleation temperature of the coolant. Other cutoff behavior is observed with respect to the initial system pressure and temperatures and with the shock pressure and rise time. Experiments with butanol and lead-tin alloy show only relatively mild interactions. Qualitative explanations are proposed for the different behaviors of the two liquids.
Date: January 1, 1979
Creator: Sharon, A. & Bankoff, S.G.
Partner: UNT Libraries Government Documents Department

Fragmentation of UO/sub 2/ and UC drops entering a sodium pool. [LMFBR]

Description: In this paper attention is focussed on whether coarse premixing of fuel and coolant is possible according to the jet penetration hypothesis, with applications to a hypothetical accident in a liquid metal cooled nuclear reactor. For UO/sub 2/ or UC fuel drops entering a sodium pool, the rapid bubble growth and collapse phenomenon, followed by crust breakup due to jet penetration, is analyzed as a function of the system pressure and coolant temperature. It appears that the UO/sub 2/-Na system fragments rapidly upon contact, for coolant temperatures above 300/sup 0/C, while the corresponding temperature for the carbide fuel is around 600/sup 0/C, at atmospheric pressures. For UO/sub 2/ but not for UC, there is a cut off pressure in the 0.1 to 3 MPa range, above which the crust does not break up for a particular coolant temperatures between 400 and 800/sup 0/C. Higher sodium temperatures aid the breakup for both fuels. One concludes that coarse premixing for UO/sub 2/, but not necessarily for UC, is difficult to attain.
Date: January 1, 1978
Creator: Ganguli, A. & Bankoff, S.G.
Partner: UNT Libraries Government Documents Department

Modeling of steady plane thermal detonations

Description: Steady plane thermal detonations proceeding through coarse fuel-coolant mixtures have been predicted to exhibit pressures of approximately 10/sup 4/ bar for UO/sub 2//Na and approximately 10/sup 3/ bar for Sn/H/sub 2/O/sup 1/. Although detailed experimental information for the crucial fragmentation step is still largely lacking, some important preliminary conclusions can nevertheless be drawn from a detailed examination of the jump balances and solution of the steady, separated-flow conservation equations in the fragmentation zone behind the shock. A few key results are presented of some parametric calculations of steady plane thermal detonations, and in addition offer some broader comments. 33 references.
Date: January 1, 1979
Creator: Bankoff, S.G. & Sharon, A.
Partner: UNT Libraries Government Documents Department

Stability of a liquid-film space radiator with internal electrostatic fields

Description: A new concept in light-weight space radiators has been introduced by Kim, Miksis and Bankoff, consisting of a pumped-loop membrane radiator in which leakage of coolant from a puncture, due to micrometeorite or space debris impact, is prevented by the application of an internal electrostatic field. For nuclear space power, the coolant is generally a liquid metal, such as lithium, flowing as a thin film along the interior walls of the hollow radiator. A lightweight fully-modular radiator design is proposed, which is calculated to weight less than 1 kg/m{sup 2}. The feature which makes this thin-membrane radiator practical is the internal electrostatic field system, which can stop radiator leaks from punctures, sudden accelerations or accidental tears.
Date: April 1, 1992
Creator: Bankoff, S.G. & Miksis, M.J.
Partner: UNT Libraries Government Documents Department

Thinning and rupture of a thin liquid film on a heated surface

Description: The objective of this work continues to be the study of dynamics, stability, and rupture (including contact line motions) of thin liquid films, especially with heat and/or mass transfer. Following the publication of a comprehensive paper on thin-film stability and rupture, taking into account evaporation (condensation), thermocapillarity, surface tension, vapor recoil, van der Waals forces, and mass loss (gain), two follow-up papers have appeared. The first examines the conditions for a non-uniformly-heated liquid film to rupture, owing to thermocapillarity, while the second reports experimental results in excellent agreement with the theory on non-isothermal free-surface problems. Another paper extends some previous results to the case where the viscosity of the liquid is a function of temperature. By proper rescaling, it is shown that the evolution equation can be transformed into the constant-viscosity case, so that previous results can be applied directly. Another paper considers the nonlinear growth, steepening, and wavebreaking of an isothermal thin liquid film draining down an inclined plate. The competition between mean flow and evaporation gives important morphological changes that control the heat-transfer process in the wavy regime. A number of other results were obtained. 9 refs.
Date: May 1, 1992
Creator: Bankoff, S.G. & Davis, S.H.
Partner: UNT Libraries Government Documents Department

Thinning and rupture of a thin liquid film on a heated surface

Description: The objective of this work continues to be the study of the dynamics, stability and rupture of thin liquid films, especially with heat and/or mass transfer. These films appear in many engineering processes, such as film coating, gas absorption, condensation, and especially cooling of hot surfaces. Surface waves may be detrimental, leading to film breakdown, with consequent equipment overheating, or beneficial, as when mass transfer coefficients are increased.
Date: January 1, 1993
Creator: Bankoff, S.G. & Davis, S.H.
Partner: UNT Libraries Government Documents Department

Interim report No. 2 on Production Test No. 105-17-P, Laboratory evaluation of proposed lubricants

Description: The lubricant (Calel A-60) used to reduce pushing forces when discharging slugs from pile tubes forms a cloudy emulsion with water. During the initial period of operation at 100 B and D areas, spillage of lubricant during discharge produced so much cloudiness in the basin water that it interfered with sorting operations. An investigation was started to see if a lubricant could be found that would effectively lubricate tubes during discharge and which would form optically clear systems when mixed with water. This report presents the data on a number of lubricants which were suggested for test.
Date: May 15, 1945
Creator: Bankoff, S. G.
Partner: UNT Libraries Government Documents Department

Prediction of the onset of significant void in transient subcooled flow boiling

Description: A new model to predict the onset of significant void (OSV) in transient subcooled flow boiling has been developed. The model is based upon the influence on vapor bubble departure of the single-phase temperature profile. The steady-state result of the present model was compared to the experimental data of Whittle and Forgan and Dougherty, et al., showing an excellent agreement. The model was then employed in a transient analysis of OSV for vertical downwards turbulent flow to predict whether OSV takes place. The condition for OSV to occur in transient flow situations was also predicted by this model. Two modes for pressure gradient change inside the channel are considered in the present study: step change and ramp change. The calculations were made for various combinations of the flow operating condition and the mode of pressure drop change.
Date: June 1, 1993
Creator: Lee, S. C. & Bankoff, S. G.
Partner: UNT Libraries Government Documents Department