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Numerical analysis of condensation induced water-hammer in horizontal piping systems

Condensation Induced Water-Hammer, CIWH, has been an
historical problem for the nuclear power industry over the
past 2 decades. It has caused damage to plant systems, and
considerable anguish to plant operators. This thesis has
embarked on an attempt to characterize the fluid motion, heat
transfer, mixing, and stability of a horizontal, stratified
flow of steam over subcooled water.
A literature review was conducted to determine the state
of numerical and analytical methods which have been applied
to this problem. The result of the review has led to the
implementation of new analytical interfacial stability
models. Information from the review has also led to the
development of correlations for wave frequency and amplitude
on the phase interface.
A numerical model has been developed to estimate the
temperature profile on the phase interface. Also, the model
will construct, by use of the above correlations, an estimate
of the interface wave structure. This wave structure is then
evaluated against a non-linear model for interface stability
to determine the onset of slug formation.
The numerical model has been used to evaluate two known
CIWH events. The results indicate that the onset of slug
formation is necessary, but not sufficient, to ensure a
water-hammer event. The results imply that there is the
possibility that once a slug has formed, it may break up
before a trapped steam void can fully collapse. The model
also indicates that CIWH in steam generator, feedwater nozzle
sections is not due to the formation of slug on an unstable
phase interface. Rather, CIWH may occur when the liquid
level inside of the feedwater nozzle is above the top of the
feedring, thus creating an isolated steam pocket. The rapid
condensation of the trapped steam in the causes CIWH. This
particular result implies that it may be possible to completely
avoid CIWH in the feedwater nozzle altogether. / Graduation date: 1991
Date21 August 1990
CreatorsEichenberg, Thomas William
ContributorsReyes, Jose N.
Source SetsOregon State University
Detected LanguageEnglish

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