The next generation of nuclear safety analysis computer codes will require detailed
modeling of two-phase fluid flow. The most complete and fundamental model used for
these calculations is known as the two-fluid model. It is the most accurate of the two-phase
models since it considers each phase independently and links the two phases
together with six conservation equations.
A major drawback is that the current two-fluid model, when area-averaged to
create a one-dimensional model, becomes ill-posed as an initial value problem when
the gas and liquid velocities are not equal. The importance of this research lies in
obtaining a model that overcomes this difficulty. It is desired to develop a modified
one-dimensional two-fluid model for horizontal flow that accounts for the pressure
difference between the two phases, due to hydrostatic head, with the implementation
of a void fraction distribution parameter. With proper improvement of the one-dimensional
two-fluid model, the next generation of nuclear safety analysis computer
codes will be able to predict, with greater precision, the key safety parameters of an
accident scenario.
As part of this research, an improved version of the one-dimensional two-fluid
model for horizontal flows was developed. The model was developed from a
theoretical point of view with the three original distribution parameters simplified
down to a single parameter. The model was found to greatly enhance the numerical
stability (hyperbolicity) of the solution method. With proper modeling of the phase
distribution parameter, a wide range of flow regimes can be modeled. This parameter
could also be used in the future to eliminate the more subjective flow regime maps that
are currently implemented in today's multiphase computer codes. By incorporating the
distribution parameter and eliminating the flow regime maps, a hyperbolic model is
formed with smooth transitions between various flow regimes, eliminating the
unphysical oscillations that may occur near transition boundaries in today's
multiphase computer codes. / Graduation date:2006
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28886 |
| Date | 25 August 2005 |
| Creators | Abel, Kent C. |
| Contributors | Wu, Qiao, Reyes, Jose N. Jr |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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