Low pressure turbine airfoils of the present generation usually operate at subsonic conditions, with exit Mach numbers of about 0.6. To reduce the costs of experimental programs it can be convenient to carry out measurements in low speed tunnels in order to determine the cascades performance. Generally speaking, low speed tests are usually carried out on airfoils with modified shape, in order to compensate for the effects of compressibility. A scaling procedure for high-lift, low pressure turbine airfoils to be studied in low speed conditions is presented and discussed. The proposed procedure is based on the matching of a prescribed blade load distribution between the low speed airfoil and the actual one. Such a requirement is fulfilled via an artificial neural network (ANN) methodology and a detailed parameterization of the airfoil. A RANS solver is used to guide the redesign process. The comparison between high and low speed profiles is carried out, over a wide range of Reynolds numbers, by using a novel three-equation, transition-sensitive, turbulence model. Such a model is based on the coupling of an additional transport equation for the so-called laminar kinetic energy (LKE) with the Wilcox k-ω model and it has proven to be effective for transitional, separated-flow configurations of high-lift cascade flows.

References

1.
Curtis
,
E. M.
,
Hodson
,
H. P.
,
Banieghbal
,
M. R.
,
Denton
,
J. D.
,
Howell
,
R. J.
, and
Harvey
,
N. W.
, 1997, “
Development of Blade Profiles for Low Pressure Turbine Applications
,”
ASME J. Turbomach.
,
119
(
3
), pp.
531
538
.
2.
Howell
,
R. J.
,
Ramesh
,
O. N.
,
Hodson
,
H. P.
,
Harvey
,
N. W.
, and
Schulte
,
V.
, 2001, “
High Lift and Aft-Loaded Profiles for Low-Pressure Turbines
,”
ASME J. Turbomach.
,
123
(
2
), pp.
181
188
.
3.
Haselbach
,
F.
,
Schiffer
,
H. P.
,
Horsman
,
M.
,
Dressen
,
S.
,
Harvey
,
N. W.
, and
Read
,
S.
, 2002, “
The Application of Ultra High Lift Blading in the BR715 LP Turbine
,”
ASME J. Turbomach.
,
124
(
1
), pp.
45
51
.
4.
Howell
,
R. J.
,
Hodson
,
H. P.
,
Schulte
,
V.
,
Stieger
,
R. D.
,
Schiffer
,
H. P.
,
Haselbach
,
F.
, and
Harvey
,
N. W.
, 2002, “
Boundary Layer Development in the BR710 and BR715 LP Turbines—The Implementation of High-Lift and Ultra-High-Lift Concepts
,”
ASME J. Turbomach.
,
124
(
3
), pp.
385
392
.
5.
Hodson
,
H. P.
, and
Dominy
,
R. G.
, 1993, “
Annular Cascades
,” Advanced Methods for Cascade Testing, AGARD-AG-328.
6.
Wisler
,
D. C.
, 1985, “
Loss Reduction in Axial Flow Compressors Through Low-Speed Model Testing
,” J. Eng. Gas Turbines Power,
107
(2)
, pp.
354
363
.
7.
Glauert
,
H.
, 1974, “
A Theory of Thin Aerofoils
,” Aeronautical Research Council R&M 910.
8.
Liepmann
,
H. W.
, and
Roshko
,
A.
, 2001,
Elements of Gasdynamics
,
Dover
,
New York
.
9.
Vera
,
M.
, and
Hodson
,
H. P.
, 2002, “
Low-Speed vs High-Speed Testing of LP Turbine Blade-Wake Interaction
,”
16th Symposium on Measuring Techniques in Transonic and Supersonic Flows in Cascades and Turbomachines
, September 23–24, Cambridge, UK.
10.
Houtermans
,
R.
,
Coton
,
T.
, and
Arts
,
T.
, 2004, “
Aerodynamic Performance of a Very High Lift Low Pressure Turbine Blade With Emphasis on Separation Prediction
,”
ASME J. Turbomach.
,
126
(
3
), pp.
406
413
.
11.
Michálek
,
J.
,
Monaldi
,
M.
, and
Arts
,
T.
, 2010, “
Aerodynamic Performance of a Very High Lift Low Pressure Turbine Airfoil (T106C) at Low Reynolds and High Mach Number With Effect of Free Stream Turbulence Intensity
,” ASME Paper No. GT2010-22884.
12.
Himmel
,
C. G.
,
Thomas
,
R. L.
, and
Hodson
,
H. P.
, 2009, “
Effective Passive Flow Control for Ultra-High Lift Low Pressure Turbines
,”
8th European Turbomach. Conf.
, Graz, Austria, pp.
17
27
.
13.
Himmel
,
C.
, and
Hodson
,
H.
, 2009, “
Modifying Ultra-High Lift Low Pressure Turbine Blades for Low Reynolds Number Applications
,”
Paper No. I12-S7-3
, 12th ISUAAAT, September 1–4, London, UK.
14.
Himmel
,
C. G.
, and
Hodson
,
H.
, 2009, “
Passive Air Jets for Loss Reductions in High Lift Low Pressure Turbines
,”
Paper No. ISABE-2009-1295
, 19th ISABE Conference, September 7–11, Montreal, Canada.
15.
Pacciani
,
R.
,
Marconcini
,
M.
,
Fadai-Ghotbi
,
A.
,
Lardeau
,
S.
, and
Leschziner
,
M. A.
, 2011, “
Calculation of High-Lift Cascades in Low Pressure Turbine Conditions Using a Three-Equation Model
,”
ASME J. Turbomach.
,
133
, p.
031016
.
16.
Pacciani
,
R.
,
Marconcini
,
M.
,
Arnone
,
A.
, and
Bertini
,
F.
, 2010, “
A CFD Study of Low Reynolds Number Flow in High Lift Cascades
,” ASME Paper No. GT2010-23300.
17.
Arnone
,
A.
,
Liou
,
M. S.
, and
Povinelli
,
L. A.
, 1992, “
Navier-Stokes Solution of Transonic Cascade Flow Using Non-Periodic C-Type Grids
,”
J. Prop. Power
,
8
(
2
), pp.
410
417
.
18.
Arnone
,
A.
, and
Pacciani
,
R.
, 1996, “
Rotor-Stator Interaction Analysis Using the Navier-Stokes Equations and a Multigrid Method
,”
ASME J. Turbomach.
,
118
(
4
), pp.
679
689
.
19.
Jameson
,
A.
, 1991, “
Time Dependent Calculations Using Multigrid With Applications to Unsteady Flows Past Airfoils and Wings
,” AIAA Paper No. 91-1596.
20.
Chorin
,
A. J.
, 1967, “
A Numerical Method for Solving Incompressible Viscous Flow Problems
,”
J. Comput. Phys.
,
2
, pp.
12
26
.
21.
Mayle
,
R. E.
, and
Schultz
,
A.
, 1997, “
The Path to Predicting Bypass Transition
,”
ASME J. Turbomach.
,
119
(
3
), pp.
405
411
.
22.
Wilcox
,
D. C.
, 1998,
Turbulence Modeling for CFD
, 2nd ed.,
DCW Ind.
,
La Cañada, CA
.
23.
Lardeau
,
S.
,
Leschziner
,
M. A.
, and
Li
,
N.
, 2004, “
Modelling Bypass Transition with Low-Reynolds-Number Nonlinear Eddy-Viscosity Closure
,”
Flow Turbul. Combust.
,
73
, pp.
49
76
.
24.
Lardeau
,
S.
,
Fadai-Ghotbi
,
A.
, and
Leschziner
,
M.
, 2009, “
Modelling Bypass and Separation-Induced Transition by Reference to Pre-Transitional Fluctuation Energy
,”
ERCOFTAC Bull. ‘Transition Modelling’
,
80
, pp.
72
76
.
25.
Hoheisel
,
H.
, 1990, “
Test Case E/CA-6, Subsonic Turbine Cascade T106, Test Cases for Computation of Internal Flows in Aero Engine Components
,” AGARD-AR-275.
26.
Pacciani
,
R.
, and
Spano
,
E.
, 2006, “
Numerical Investigation of the Effect of Roughness and Passing Wakes on LP Turbine Blades Performance
,” ASME Paper No. GT2006-90221.
27.
Gaster
,
M.
, 1969, “
The Structure and Behaviour of Laminar Separation Bubbles
,” Aeronautical Research Council R&M 3595.
28.
Pianko
,
M.
, and
Wazelt
,
F.
, 1982, “
Averaging Techniques in Non-Uniform Internal Flows
,” AGARD-AR-182.
29.
Cichocki
,
A.
, and
Unbehauen
,
R.
, 1994,
Neural Networks for Optimization and Signal Processing
,
John Wiley
,
New York
.
30.
Rubechini
,
F.
,
Schneider
,
A.
,
Arnone
,
A.
,
Cecchi
,
S.
, and
Malavasi
,
F.
, 2012, “
A Redesign Strategy to Improve the Efficiency of a 17-Stage Steam Turbine
,” ASME J. Turbomach.,
134
, p.
031021
.
31.
Rai
,
M. M.
, 2002, “
Three-Dimensional Aerodynamic Design Using Artificial Neural Networks
,” AIAA Paper No. 2002-0987.
32.
Coull
,
J. D.
,
Thomas
,
R. L.
, and
Hodson
,
H. P.
, 2010, “
Velocity Distributions for Low Pressure Turbines
,”
ASME J. Turbomach.
,
132
, p.
041006
.
33.
Hatman
,
A.
, and
Wang
,
T.
, 1999, “
A Prediction Model for Separated-Flow Transition
,”
ASME J. Turbomach.
,
121
(
3
), pp.
594
602
.
34.
Lou
,
W.
, and
Hourmouziadis
,
J.
, 2000, “
Separation Bubbles Under Steady and Periodic-Unsteady Main Flow Conditions
,”
ASME J. Turbomach.
,
122
(
4
), pp.
634
643
.
35.
Hourmouziadis
,
J.
, and
Hofmann
,
G.
, 2006, “
Response of Separation Bubble to Velocity and Turbulence Wakes
,”
NASA CP-214484, Proceedings of Minnowbrook V - 2006 Workshop on Unsteady Flows in Turbomachinery
.
You do not currently have access to this content.