Effects of scalloping on the mixing mechanisms of forced mixers with highly swirling core flow

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DOIResolve DOI: http://doi.org/10.1115/1.4024043
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TypeArticle
Journal titleJournal of Engineering for Gas Turbines and Power
ISSN0742-4795
Volume135
Issue7
Article number71202
SubjectComputational investigation; Mixing mechanisms; Pressure loss; Reduced pressure; Reynolds-Averaged Navier-Stokes; Separation bubble; Suction surfaces; Swirl angles; Computer simulation; Mixing; Molluscs; Navier Stokes equations; Vortex flow; Mixers (machinery)
AbstractThis paper presents a detailed experimental and computational investigation of the effects of scalloping on the mixing mechanisms of a scaled 12-lobe turbofan mixer. Scalloping was achieved by eliminating approximately 70% of the lobe sidewall area. Measurements were made downstream of the mixer in a co-annular wind tunnel, and the simulations were carried out using an unstructured Reynolds averaged Navier-Stokes (RANS) solver, Numeca FINE/Hexa, with k-Ω SST model. In the core flow, the swirl angle was varied from 0 deg to 30 deg. At high swirl angles, a three-dimensional separation bubble was formed on the lobe's suction surface penetration region and resulted in the generation of a vortex at the lobe valley. The valley vortex quickly dissipated downstream. The mixer lobes removed most of the swirl, but scalloped lobes removed less swirl in the region of the scalloped notch. The residual swirl downstream of the scalloped mixer interacted with the vortices and improved mixing rates compared to the unscalloped mixer. Core flow swirl up to 10 deg provided improved mixing rates and reduced pressure and thrust losses for both mixers. As core flow swirl increased beyond 10 deg, the mixing rate continued to improve, but pressure and thrust losses declined compared to the zero swirl case. Lobe scalloping, in high swirl conditions, resulted in better mixing and improved pressure loss over the unscalloped mixer but at the expense of reduced thrust. Copyright © 2013 by ASME.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); Aerospace (AERO-AERO)
Peer reviewedYes
NPARC number21269697
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Record identifiera2f34d67-ec0d-4aed-9136-6bdcf36b35d8
Record created2013-12-13
Record modified2016-05-09
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