A computational study of the multirow interaction mechanisms has been carried out for a one-and-a-half stage (NGV-rotor-stator) transonic turbine. In addition to measurable subharmonic unsteadiness on the rotor blades induced by two fundamental stator passing frequencies, a significant aperiodic (“mistuned”) circumferential variation of unsteady forcing magnitude by about three times has been observed in the downstream stator blades. Further parametric studies with various stator blade counts illustrate that the circumferential variation pattern of the unsteady forcing is dictated by the NGV-stator blade count difference, while the local stator forcing magnitude is affected by its circumferential clocking position relative to the upstream NGV blades. The present work suggests that the circumferential clocking together with the choice of blade count should be considered as an aeromechanical design parameter. For cases with stator-stator (or rotor-rotor) blade counts resulting in a tuned (or nearly tuned) unsteady forcing pattern, the clocking position should be chosen to minimize the unsteady forcing. On the other hand, if the choice of blade counts leads to a significant aerodynamic aperiodicity (mistuning), the clocking-forcing analysis can be used to identify the most vulnerable blade that is subject to the maximum forcing.

1.
Capece
,
V. R.
,
Manwaring
,
S. R.
, and
Fleeter
,
S.
,
1986
, “
Unsteady Blade Row Interactions in a Multi-stage Compressor
,”
AIAA J., Propul. Power
2
(
2
), pp.
168
174
.
2.
Hsu
,
S. T.
, and
Wo
,
A. M.
,
1998
, “
Reduction of Unsteady Blade Loading by Beneficial Use of Vortical and Potential Disturbances in an Axial Compressor with Rotor Clocking
,”
ASME J. Turbomach.
,
120
, pp.
705
713
.
3.
Huber
,
F. W.
,
Johnson
,
P. D.
,
Sharma
,
O. P.
,
Staubach
,
J. B.
, and
Goddis
,
S. W.
,
1996
, “
Performance Improvement Through Indexing of Turbine Airfoils: Part I-Experimental Investigation
,”
ASME J. Turbomach.
,
118
, pp.
630
635
.
4.
Griffin
,
L. W.
,
Huber
,
F. W.
, and
Sharma
,
O. P.
,
1996
, “
Performance Improvement Through Indexing of Turbine Airfoils: Part II-Numerical Simulation
,”
ASME J. Turbomach.
,
118
, pp.
636
642
.
5.
Dorney, D. J., and Sharma, O. P., 1996, “A Study of Turbine Performance Increase Through Airfoil Clocking,” AIAA Paper No. 96-2816.
6.
Cizmas, P., and Dorney, D. J., 1998, “Parallel Computation of Turbine Blade Clocking,” AIAA Paper No. 98-3598.
7.
Arnone
,
A.
,
Marconcini
,
M.
,
Pacciani
,
R.
,
Schipani
,
C.
, and
Spano
,
E.
,
2002
, “
Numerical Investigation of Airfoil Clocking in a Three-Stage Low-Pressure Turbine
,”
ASME J. Turbomach.
,
124
, pp.
61
68
.
8.
Reinmoller
,
U.
,
Stephan
,
B.
,
Schmidt
,
S.
, and
Niehuis
,
R.
,
2002
, “
Clocking Effects in 1 1.5 Stage Axial Turbine-Steady and Unsteady Experimental Investigations Supported by Numerical Simulations
,”
ASME J. Turbomach.
,
124
, pp.
52
60
.
9.
Hummel
,
F.
,
2002
, “
Wake-Wake Interaction and Its Potential for Clocking in A Transonic High Pressure Turbine
,”
ASME J. Turbomach.
,
124
, pp.
69
76
.
10.
Kielb
,
R. E.
, and
Kaza
,
K. R. V.
,
1984
, “
Effects of Structural Coupling on Mistuning Cascade Flutter and Response
,”
ASME J. Eng. Gas Turbines Power
,
106
, pp.
17
24
.
11.
Miller
,
R. J.
,
Moss
,
R. W.
,
Ainsworth
,
R. W.
, and
Harvey
,
N. W.
,
2001
, “
Time-Resolved Vane-Rotor-Vane Interaction in A Transonic One and A Half Stage Turbine
,”
Proc. of IMechE, Part A, J. of Power and Energy
,
215
, pp.
675
685
.
12.
Baldwin, B. S., and Lomax, H., 1978, “Thin Layer Approximation and Algebraic Model for Separated Turbulent Flows,” AIAA Paper 78-0257.
13.
Jameson, A., Schmidt, W., and Turkel, E., 1981, “Numerical Solutions of the Euler Equations by Finite Volume Method using Runge-Kutta Time-Stepping Scheme,” AIAA Paper 81-1259.
14.
He
,
L.
,
2000
, “
Three-Dimensional Unsteady Navier-Stokes Analysis of Stator-Rotor Interaction in Axial-Flow Turbines
,”
Proc. of IMechE, Part A, J. of Power and Energy
,
214
, pp.
13
22
.
15.
Giles
,
M. B.
,
1990
, “
Nonreflecting Boundary Conditions for Euler Equation Calculations
,”
AIAA J.
,
28
, No.
12
, pp.
2050
2058
.
16.
Moss, R. W., Ainsworth, R. W., Sheldrake C. D., and Miller, R., 1997, “The Unsteady Pressure Field Over a Turbine Blade Surface: Visualisation and Interpretation of Experimental Data,” ASME Paper 97-GT-474.
You do not currently have access to this content.