Drag Characteristics of Objects in Two-phase Boiling Flows

Keywords

Skin friction coefficient, Form drag on cylinders and spheres, Laminar vapor film flow, Drag-bucket phenomenon, Water–steam two-phase flow (atmospheric pressure)

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

This item is only available in print in the UCF Libraries. If this is your thesis or dissertation, you can help us make it available online for use by researchers around the world by STARS for more information.

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

PDF

Pages

417 pages

Language

English

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Identifier

DP0026636

Subjects

Dissertations; Academic -- Engineering; Engineering -- Dissertations; Academic; Film boiling; Two-phase flow--Mathematical models; Drag (Aerodynamics)--Mathematical models; Frictional resistance (Hydrodynamics)--Mathematical models; Two-phase flow--Research

Accessibility Status

Searchable text

This document is currently not available here.

Share

COinS