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Research Papers

Transition Modeling for Vortex Generating Jets on Low-Pressure Turbine Profiles

[+] Author and Article Information
Florian Herbst

Research Assistant
Institute of Turbomachinery and Fluid Dynamics
Leibniz Universitaet Hannover
Hannover, 30167, Germany
e-mail: Herbst@tfd.uni-hannover.de

Dragan Kožulović

Professor
Member of ASME
Institute of Fluid Mechanics
Technische Universitaet Braunschweig
Braunschweig, 38106, Germany
e-mail: D.Kozulovic@tu-braunschweig.de

Joerg R. Seume

Professor
Senior Member ASME
Institute of Turbomachinery and Fluid Dynamics
Leibniz Universitaet Hannover
Hannover, 30167, Germany
e-mail: Seume@tfd.uni-hannover.de

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 29, 2011; final manuscript received August 10, 2011; published online October 31, 2012. Editor: David Wisler.

J. Turbomach 135(1), 011038 (Oct 31, 2012) (8 pages) Paper No: TURBO-11-1167; doi: 10.1115/1.4006421 History: Received July 29, 2011; Revised August 10, 2011

Steady blowing vortex generating jets (VGJ) on highly-loaded low-pressure turbine profiles have shown to be a promising way to decrease total pressure losses at low Reynolds-numbers by reducing laminar separation. In the present paper, the state of the art turbomachinery design code TRACE with RANS turbulence closure and coupled γ-ReΘ transition model is applied to the prediction of typical aerodynamic design parameters of various VGJ configurations in steady simulations. High-speed cascade wind tunnel experiments for a wide range of Reynolds-numbers, two VGJ positions, and three jet blowing ratios are used for validation. Since the original transition model overpredicts separation and losses at Re2is100·103, an extra mode for VGJ induced transition is introduced. Whereas the criterion for transition is modeled by a filtered Q vortex criterion the transition development itself is modeled by a reduction of the local transition-onset momentum-thickness Reynolds number. The new model significantly improves the quality of the computational results by capturing the corresponding local transition process in a physically reasonable way. This is shown to yield an improved quantitative prediction of surface pressure distributions and total pressure losses.

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References

Figures

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Fig. 1

Vortex structures of a jet in crossflow configuration according to Ref. [17]

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Fig. 5

T161 high-lift LPT profile with two VGJ-configurations, type I at 63% and type II at 69% axial length, with d/lax = 0.020 and j/d = 10 (distorted geometry)

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Fig. 4

VGJ transition criterion FVGJ

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Fig. 3

Flat plate setup with boundary conditions (translational-periodic boundary condition in z-direction)

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Fig. 2

Q vortex criterion at VGJ flat plate setup

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Fig. 8

Mesh of type I VGJ, every second grid line shown (distorted geometry)

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Fig. 6

ζV of Re2is=200·103 (left) and ζV, m for Re2is=50·103...400·103 (right) without AFC

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Fig. 7

cp of Re2is=70·103 (left) and 200·103 (right) without AFC

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Fig. 9

cp of Re2is=70·103, type I, B = 0.5 (left) and associated magnification of the trailing edge region (right)

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Fig. 10

ζV of Re2is=70·103 (left) and ζV, m for Re2is=50·103...400·103 (right), type I, B = 0.5

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Fig. 11

Isosurface FVGJ = 1 at Re2is=70·103, type I, B = 0.5 (geometry distorted)

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Fig. 12

ζV, m for Re2is=50·103...200·103 (left) and cp of Re2is=70·103 (right), type I, B = 1.0

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Fig. 13

ζV, m for Re2is=50·103...120·103 (left) and cp of Re2is=70·103 (right), type II, B = 1.0

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Fig. 14

ζV, m (left) and cp (right) at Re2is=70·103, type II, B = 1.5

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Fig. 15

μt/μ downstream VGJ without (upper) and with (lower) VGJ transition mode, at Re2is=70·103, type I, B = 0.5 (geometry distorted)

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Fig. 16

Boundary layer separation (derived form τw) at the profile’s suction side without (upper) and with (lower) VGJ transition mode, at Re2is=70·103, type I, B = 0.5

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