Experimental investigation on vortex shedding in flow over second-generation, controlled-diffusion, compressor blades in cascade
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Authors
Brown, Peter J.
Subjects
Controlled-diffusion
Compressor
Stator
Cascade
Turbomachinery
Hot-wire anemometry
Laser Doppler velocimetry
Vortex shedding
Compressor
Stator
Cascade
Turbomachinery
Hot-wire anemometry
Laser Doppler velocimetry
Vortex shedding
Advisors
Hobson, Garth V.
Date of Issue
2002-03
Date
March 2002
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
An investigation of vortex shedding downstream of a cascade of second-generation, controlled-diffusion, compressor stator blades, at off-design inlet-flow angles of 31, 33 and 35 degrees and Reynolds numbers, based on chord length, of 280,000, 380,000 and 640,000 is reported. The objective of the study was to characterize the flow and shedding through various complementary methods. Blade surface pressure measurements were taken from a fully instrumented blade, and distributions of pressure coefficients were determined. Five-hole probe wake surveys were performed at midspan, and the total pressure loss coefficients and axial velocity ratios were calculated. Upstream inlet-flow angle was set, and further characterized through two-component laser-Doppler velocimetry (LDV). Hot-wire anemometry measurements were performed at mid span, in the wake, and the reduced data were compared with two-component LDV surveys of the same regions. Plots of hot-wire vs. LDV turbulence data are reported in addition to power spectra documenting the shedding events. Vortex shedding was determined to be a leading edge phenomenon as periodic shedding was only detected on the pressure side of the wake. The frequency and magnitude of shedding were found to be independent of incidence angle, and to increase with Reynolds number at constant incidence angle. The Strouhal number, based on leading edge diameter, was found to be in the range of 0.23-0.26, which is comparable to that of vortex shedding behind a circular cylinder in the Reynolds number range tested.
Type
Thesis
Description
Series/Report No
Department
Aeronautics and Astronautics
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
xvi, 88 p. : ill. ;
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.