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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

## Abstract

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 $Re2is≤100·103$, 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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## Figures

Fig. 1

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

Fig. 2

Q vortex criterion at VGJ flat plate setup

Fig. 3

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

Fig. 4

VGJ transition criterion FVGJ

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)

Fig. 6

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

Fig. 7

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

Fig. 8

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

Fig. 9

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

Fig. 10

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

Fig. 11

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

Fig. 12

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

Fig. 13

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

Fig. 14

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

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)

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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