Effects of core flow swirl on the flow characteristics of a scalloped forced mixer

DOIResolve DOI: http://doi.org/10.1115/GT2011-46726
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Proceedings titleProceedings of the ASME Turbo Expo
ConferenceASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, GT2011, 6 June 2011 through 10 June 2011, Vancouver, BC
Pages451463; # of pages: 13
SubjectCore flow; Experimental investigations; Flow characteristic; Hydraulic diameter; Inlet swirls; Low swirl; Normal vortices; Pressure probes; Pressure ratio; Radial velocity; Reversed flow; Streamwise vortices; Surface oil flow; Swirl angles; Temperature ratio; Thrust loss; Total pressure; Turbulence intensity; Vane geometry; Velocity ratio; Acoustic streaming; Aircraft engines; Alternative fuels; Bypass ratio; Deformation; Exhibitions; Flow visualization; Hydraulic motors; Mixers (machinery); Reynolds number; Vortex flow; Mixing
AbstractThis paper presents a detailed experimental investigation of the influence of core flow swirl on the mixing and performance of a scaled turbofan mixer with 12 scalloped lobes. Measurements were made downstream of the mixer in a co-annular wind tunnel. The core-to-bypass velocity ratio was set to 2:1, temperature ratio to 1.0, and pressure ratio to 1.03, giving a Reynolds number of 5.2×105, based on the core flow velocity and equivalent hydraulic diameter. In the core flow, the background turbulence intensity was raised to 5% and the swirl angle was varied using five vane geometries from 0° to 30°. Seven-hole pressure probe measurements and surface oil flow visualization were used to describe the flowfield and the mixer performance. At low swirl angles, additional streamwise vortices were generated by the deformation of normal vortices due to the scalloped lobes. With increased core swirl, greater than 10°, the additional streamwise vortices were generated mainly due to radial velocity deflection, rather than stretching and deformation of normal vortices. At high swirl angles, stronger streamwise vortices and rapid interaction between various vortices promoted downstream mixing. Mixing was enhanced with minimal or no total pressure and thrust losses for the inlet swirl angles less than 10°. However, the reversed flow downstream of the center-body was a dominant contributor to the loss of thrust at the maximum core flow swirl angle of 30°. Copyright © 2011 by ASME.
Publication date
AffiliationNational Research Council Canada (NRC-CNRC); Aerospace (AERO-AERO)
Peer reviewedYes
NPARC number21271062
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Record identifierc54c7e1e-271f-4d5f-9bd9-80dc6b1a8410
Record created2014-03-24
Record modified2016-05-09
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