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A Linear Dynamic Analysis of Vent Condensation Stability

Brennen, C. (1980) A Linear Dynamic Analysis of Vent Condensation Stability. In: Basic mechanisms in two-phase flow and heat transfer / presented at the winter annual meeting of the American Society of Mechanical Engineers, Chicago, Illinois, November 16-21, 1980 ; sponsored jointly by Fluids Engineering Division (PFC), ... American Society of Mechanical Engineers , New York, pp. 63-71.

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Pressure suppression systems in boiling water reactors are designed to condense a large amount of steam very rapidly by injecting it into a pool of water. It transpires that such condensing flows are unstable and can lead to large oscillatory pressures on the walls of the containment system. This paper presents a theoretical model whose purpose is to attempt to understand why these flows are unstable and to extract the important parameters and frequencies pertaining to the instability. A simple linear dynamic model is constructed comprising linear transfer function for (i) the unsteady steam flow in the vent (ii) the condensation interface and (iii) the pool hydrodynamics. The analysis demonstrates the existence of both stable and unstable regions of operation defined by several non-dimensional parameters including the ratio of the steam flow rate to the effective thermal diffusivity in the water just downstream of the condensation interface and the frictional losses in the vent. Instability frequencies are in the vicinity of the vent acoustic frequencies or the pool manometer frequency depending on the conditions. Though the qualitative dynamic behavior of the model is consistent with the experimental observations, quantitative comparison is hindered by difficulties in accurately assessing the effective thermal diffusivity in the water. Nevertheless the model provides insight into the nature of the instability.

Item Type:Book Section
Additional Information:This paper was prepared partly with support from the National Science Foundation under Grant Eng. 76-11225, for which the author is most grateful.
Funding AgencyGrant Number
NSFEng. 76-11225
Record Number:CaltechAUTHORS:CEBbmtpfht80
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:190
Deposited By: Christopher Brennen
Deposited On:17 Nov 2004
Last Modified:02 Oct 2019 22:31

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