Drag Characteristics of Objects in Two-phase Boiling Flows
Abstract
One aspect ot boiling that has received little investigation is the effect of boiling on the fluid-dynamic drag on objects. In addition to enhancing our understanding of the boiling processes, this aspect has been identified to have some scientific applications in nuclear safety analyses. A theoretical analysis of the drag characteristics of objects in two-phase boiling flows is presented and a theoretical model is developed to quantify the drag characteristics in the film boiling regime. The geometries investigated include a flat plate, wedge, circular cylinder and a sphere. The latter two geometries are considered in the context of film boiling form drag. The results of this dissertation effort indicate (for a water-steam system at atmospheric pressure) that the skin friction coefficient parameter on a flat plate or a wedge in a laminar film boiling flow may increase, remain the same or decrease beyond the single-phase flow level, depending upon free stream velocity, surface temperature, geometry, orientation and liquid subcooling. The external pressure gradient and or the stream-wise buoyancy force driving the vapor film may cause the skin friction coefficient to exhibit a "drag bucket type phenomenon" at increased wall temperatures.
Notes
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Graduation Date
1989
Semester
Spring
Advisor
Gunnerson, Fred
Degree
Doctor of Philosophy (Ph.D.)
College
College of Engineering
Department
Mechanical Engineering and Aerospace Sciences
Format
Pages
417 p.
Language
English
Length of Campus-only Access
None
Access Status
Doctoral Dissertation (Open Access)
Identifier
DP0026636
Subjects
Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic
STARS Citation
Chappidi, Padmanabha R., "Drag Characteristics of Objects in Two-phase Boiling Flows" (1989). Retrospective Theses and Dissertations. 4115.
https://stars.library.ucf.edu/rtd/4115
Accessibility Status
Searchable text