Date of Award

12-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Beasley, Donald E

Committee Member

Figiliola , Richard S

Committee Member

Miller , Richard S

Abstract

The main goal of this project is to investigate how changes in support grid mixing vane angles affect the single phase heat transfer coefficient for rod bundle flows. Since other studies have been done on these types of flows, the present study also serves the purpose of further solidifying conclusions made in those works. A split-pair mixing vane support grid without weld nugget cutouts is thought to have optimum flow characteristics at a vane angle of 29 degrees. Results obtained from this work have shown this to be true. Vane angles were modified to angles of 37 ¡, 33¡ and 21¡ using a custom designed tool and visually inspected using gauge blocks. Data was also taken at the original angle of 29¡ as a baseline. Temperature measurements were directly obtained from the rod surface using a sensor comprised of 4 E-type thermocouples. Because of the known behavior of rod bundle subchannel flows, temperature measurements were taken between -5 and 40 hydraulic diameters with respect to the support grid's trailing edge. At each axial location, the sensor was rotated at 22.5¡ increments for a total of 16 angular measurement positions at the inner surface of the rod. Forced convection heat transfer was achieved by way of direct resistance heating of the rods and a high speed, pressure driven air flow. The maximum flow rate available is utilized for each test but ranged from 24,000 to 30,000 (Re) because of ambient air temperature variations. For repeatability purposes, current and voltage were set at approximately 700 amps and 4 volts respectively for each test. Results from this study along with parallel research include but are not limited to the following; circumferentially averaged Nusselt Numbers, azimuthal heat transfer variation and average turbulent kinetic energy. From a systems perspective, any information directly pertaining to heat transfer on the fuel rod's surfaces will be helpful in the future as nuclear power becomes more prevalent. This study includes a brief introduction of the work being presented as well as a summary of past works. Along with the background information, a detailed overview of the experimental facility and method is presented. In the latter sections of this thesis, all results obtained have been thoroughly analyzed and conclusions have been made accordingly.

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