Abstract

High cycle fatigue (HCF) is a common problem in military turbofan engines, resulting in engine component failure, and billions of dollars a year in repair and maintenance. HCF occurs due to engine component aerodynamic interactions, including vortical and potential field effects. In 1987, the IHPTET program was created by the U.S. Department of Defense. One of the goals of this program was to reduce high cycle fatigue in engine components. A method of reducing the amount of HCF occurring in a turbofan engine is referred to as trailing edge blowing (TEB). TEB reduces the vortical, or wake, components of a fluid flow that propagate from upstream stator blades, to impinge on the surfaces of downstream rotor blades, one of the causes of HCF. The experimental results from the study of an F109 turbofan engine showed that TEB did reduce the amount of HCF related stress on the rotor blades; however, the amount of TEB used compromised the overall efficiency of the compressor by too high an amount. Thus, it is necessary to find an optimal level of TEB to achieve reduction in HCF forces, while maintaining high compressor efficiency. Due to the absence of an engine test stand for experimental testing, the solution was simulated using computational fluid dynamics (CFD). The current investigation focuses on the necessary preliminary steps taken in optimizing TEB, using CFD. TEB was not simulated, however the following investigation paves the way for future CFD work, including a method of incorporating TEB into a CFD simulation. The work also outlines the mistakes made, so that they are not made again by future researchers, as well as the recommended methods of modeling the F109 stator-rotor system using CFD. To the knowledge of the current investigator, using CFD to model rotor blade surface pressures in the F109 turbofan engine, due to the presence of upstream stators, has not previously been attempted.

Library of Congress Subject Headings

Compressors--Blades--Mathematical models; Fluid dynamics--Computer programs

Publication Date

2004

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Elizabeth DeBartolo

Advisor/Committee Member

Jeffrey Kozak

Advisor/Committee Member

Kevin Kochersberger

Comments

Physical copy available from RIT's Wallace Library at TJ990 .B37 2004

Campus

RIT – Main Campus

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