Defense Date

2002

Document Type

Thesis

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Eric Sandgren

Abstract

Axial turbomachines have inherently unstable flow fields due to the interaction between rotating and nonrotating blade rows. In addition, combustor instabilities add considerable stress on the blading via the introduction of localized radial and/or circumferential temperature discontinuities known as hot streaks. To alleviate the losses due to nonconformities within the turbine a computational effort has been undertaken investigating the effects of clocking an imbedded stage in a multi- stage axial turbine and a separate study considering the effects of an imposed temporally oscillating hot streak within a 1 1/2 stage turbine. Time-dependent hot streak results show little relation of rotor surface heating to hot streak frequency (non-dimensional) for hot streak frequencies less than unity. The general trend for stator 2 is observed to be as hot streak frequency increases stator 2 observes a decreasing trend in surface heating for frequencies less than unity. At unity rotor surface heating is minimized and stator 2 surface heating is maximized, if the rotor is properly phased (180°) with the hot streak. When the hot streak is in phase with the rotor a rotor maximum surface temperature is observed and the stator 2 is at a minimum. Multi-stage clocking shows a periodic effect on loss and efficiency for the clocked airfoils and the rotor between. Loss and effeciency in the current study are observed to vary inversely to one another with high vane loss corresponding to higher efficiency in the vane rows, while high loss in the vane corresponds to low losses of greater magnitude in the rotor row.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-12-2016

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