Date of Award

2017

Publisher

North Dakota State University

Document Type

Thesis

Degree Awarded

Master of Science (MS)

Program

Mechanical Engineering

Department

Mechanical Engineering

College

Engineering

Faculty Advisor

Suzen, Bora

Description

A numerical analysis is performed at North Dakota State University to investigate and resolve steam inlet control valve vibration in a Minnkota Power Cooperative turbine. Pressure fluctuations resulting from an unstable flow pattern are found to cause vibration. Multiple valve disc and seat design modifications to stabilize the flow are made and tested. The full scale geometry is used with steam as the working material. Both steady-state and transient analyses are completed. Analytical calculations are used for verification. Investigation of all modifications is discussed. Results from the original valve configuration show vortex shedding off of the disc. A currently installed cutoff disc has not removed flow-induced vibration. Flow expansion generates unstable flow, creating an unsteady separation bubble on the valve seat at the throat exit. Changing the throat from a converging-diverging to a purely converging nozzle stabilizes the flow, removing the flow-induced pressure forces causing disc vibration.

Rights

NDSU Policy 190.6.2

Rights Link

https://www.ndsu.edu/fileadmin/policy/190.pdf

Handle Identifier

https://hdl.handle.net/10365/28042

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