This work aims at investigating the impact of axial gap variation on aerodynamic performance of a high-pressure steam turbine stage. Numerical and experimental campaigns were conducted on a 1.5-stage of a reaction steam turbine. This low speed test rig was designed and operated in different operating conditions. Two different configurations were studied in which blades axial gap was varied in a range from 40% to 95% of the blade axial chord. Numerical analyses were carried out by means of three-dimensional, viscous, unsteady simulations, adopting measured inlet/outlet boundary conditions. Two sets of measurements were performed: steady measurements, from one hand, for global performance estimation of the whole turbine, such as efficiency, mass flow, and stage work; steady and unsteady measurements, on the other hand, were performed downstream of rotor row, in order to characterize the flow structures in this region. The fidelity of computational setup was proven by comparing numerical results to measurements. Main performance curves and spanwise distributions have shown a good agreement in terms of both shape of curves/distributions and absolute values. Moreover, the comparison of two-dimensional maps downstream of rotor row has shown similar structures of the flow field. Finally, a comprehensive study of the axial gap effect on stage aerodynamic performance was carried out for four blade spacings (10%, 25%, 40%, and 95% of S1 axial chord) and five aspect ratios (1.0, 1.6, 3, 4, and 5). The results pointed out how unsteady interaction between blade rows affects stage operation, in terms of pressure and flow angle distributions, as well as of secondary flows development. The combined effect of these aspects in determining the stage efficiency is investigated and discussed in detail.

References

References
1.
Bellucci
,
J.
,
Rubechini
,
F.
, and
Arnone
,
A.
,
2015
, “
Some Experiences About the Impact of Unsteadiness in Turbine Flows
,”
ASME
Paper No. GT2015-43122.
2.
Pullan
,
G.
,
2006
, “
Secondary Flows and Loss Caused by Blade Row Interaction in a Turbine Stage
,”
ASME J. Turbomach.
,
128
(
3
), pp.
484
491
.
3.
Denton
,
J. D.
,
1993
, “
The 1993 IGTI Scholar Lecture: Loss Mechanisms in Turbomachines
,”
ASME J. Turbomach.
,
115
(4), pp.
621
656
.
4.
Chaluvadi
,
V. S. P.
,
Kalfas
,
A. I.
, and
Hodson
,
H. P.
,
2004
, “
Vortex Transport and Blade Interactions in High Pressure Turbines
,”
ASME J. Turbomach.
,
126
(
3
), pp.
395
405
.
5.
Venable
,
B. L.
,
Delaney
,
R. A.
,
Busby
,
J. A.
,
Dorney
,
R. L.
,
Dunn
,
M. G.
,
Haldeman
,
C. W.
, and
Abhari
,
R. S.
,
1999
, “
Influence of Vane–Blade Spacing on Transonic Turbine Stage Aerodynamics—Part I: Time-Averaged Data and Analysis
,”
ASME J. Turbomach.
,
121
(
4
), pp.
663
672
.
6.
Walraevens
,
R. E.
,
Gallus
,
H. E.
,
Jung
,
A. R.
,
Mayer
,
J. F.
, and
Stetter
,
H.
,
1998
, “
Experimental and Computational Study of the Unsteady Flow in a 1.5 Stage Axial Turbine With Emphasis on the Secondary Flow in the Second Stator
,”
ASME
Paper No. 98-GT-254.
7.
Ristic
,
D.
,
Lakshminarayana
,
B.
, and
Chu
,
S.
,
1999
, “
Three-Dimensional Flowfield Downstream of an Axial-Flow Turbine Rotor
,”
J. Propul. Power
,
15
(
2
), pp.
334
344
.
8.
Gaetani
,
P.
,
Persico
,
G.
, and
Osnaghi
,
C.
,
2010
, “
Effects of Axial Gap on the Vane-Rotor Interaction in a Low Aspect Ratio Turbine Stage
,”
J. Propul. Power
,
26
(
2
), pp.
325
334
.
9.
Pullan
,
G.
, and
Denton
,
J. D.
,
2003
, “
Numerical Simulations of Vortex-Turbine Blade Interaction
,”
5th European Turbomachinery Conference
, Prague, Czech Republic, Mar. 7–11.
10.
Yamada
,
K.
,
Funazaki
,
K.
,
Kikuchi
,
M.
, and
Sato
,
H.
,
2009
, “
Influences of Axial Gap Between Blade Rows on Secondary Flows and Aerodynamic Performance in a Turbine Stage
,”
ASME
Paper No. GT2009-59855.
11.
Rubechini
,
F.
,
Marconcini
,
M.
,
Giovannini
,
M.
,
Bellucci
,
J.
, and
Arnone
,
A.
,
2015
, “
Accounting for Unsteady Interaction in Transonic Stages
,”
ASME J. Eng. Gas Turbines Power
,
137
(
5
), p.
052602
.
12.
Arnone
,
A.
,
1994
, “
Viscous Analysis of Three-Dimensional Rotor Flow Using a Multigrid Method
,”
ASME J. Turbomach.
,
116
(
3
), pp.
435
445
.
13.
Spalart
,
P. R.
, and
Allmaras
,
S. R.
,
1994
, “
A One-Equation Turbulence Model for Aerodynamic Flows
,”
Rech. Aérosp.
,
1
, pp.
5
21306
.
14.
Wilcox
,
D. C.
,
2008
, “
Formulation of the k–ω Turbulence Model Revisited
,”
AIAA J.
,
46
(
11
), pp.
2823
2838
.
15.
Menter
,
F. R.
,
1994
, “
Two–Equations Eddy Viscosity Turbulence Models for Engineering Applications
,”
AIAA J.
,
32
(
8
), pp.
1598
1605
.
16.
Arnone
,
A.
,
Liou
,
M. S.
, and
Povinelli
,
L. A.
,
1992
, “
Navier–Stokes Solution of Transonic Cascade Flow Using Non-Periodic C-Type Grids
,”
J. Propul. Power
,
8
(
2
), pp.
410
417
.
17.
Arnone
,
A.
,
Carnevale
,
E.
, and
Marconcini
,
M.
,
1997
, “
Grid Dependency Study for the Nasa Rotor 37 Compressor Blade
,”
ASME
Paper No. 97–GT–384.
18.
Giovannini
,
M.
,
Marconcini
,
M.
,
Arnone
,
A.
, and
Bertini
,
F.
,
2014
, “
Evaluation of Unsteady Computational Fluid Dynamics Models Applied to the Analysis of a Transonic High-Pressure Turbine Stage
,”
Proc. Inst. Mech. Eng. Part A
,
228
(
7
), pp.
813
824
.
19.
Pacciani
,
R.
,
Rubechini
,
F.
,
Arnone
,
A.
, and
Lutum
,
E.
,
2012
, “
Calculation of Steady and Periodic Unsteady Blade Surface Heat Transfer in Separated Transitional Flow
,”
ASME J. Turbomach.
,
134
(
6
), p.
061037
.
20.
Marconcini
,
M.
,
Rubechini
,
F.
,
Arnone
,
A.
, and
Ibaraki
,
S.
,
2010
, “
Numerical Analysis of the Vaned Diffuser of a Transonic Centrifugal Compressor
,”
ASME J. Turbomach.
,
132
(
4
), p.
041012
.
21.
Bonaiuti
,
D.
,
Arnone
,
A.
,
Hah
,
C.
, and
Hayami
,
H.
,
2002
, “
Development of Secondary Flow Field in a Low Solidity Diffuser in a Transonic Centrifugal Compressor Stage
,”
ASME
Paper No. 2002-GT-30371.
22.
Schmitt
,
S.
,
Eulitz
,
F.
,
Wallscheid
,
L.
,
Arnone
,
A.
, and
Marconcini
,
M.
,
2001
, “
Evaluation of Unsteady CFD Methods by Their Application to a Transonic Propfan Stage
,”
ASME
Paper No. 2001–GT–310.
23.
Marconcini
,
M.
,
Rubechini
,
F.
,
Arnone
,
A.
,
Scotti Del Greco
,
A.
, and
Biagi
,
R.
,
2012
, “
Aerodynamic Investigation of a High Pressure Ratio Turbo-Expander for Organic Rankine Cycle Applications
,”
ASME
Paper No. GT2012-69409.
24.
Rubechini
,
F.
,
Marconcini
,
M.
,
Arnone
,
A.
,
Scotti Del Greco
,
A.
, and
Biagi
,
R.
,
2013
, “
Special Challenges in the Computational Fluid Dynamics Modeling of Transonic Turbo-Expanders
,”
ASME J. Eng. Gas Turbines Power
,
135
(10), p. 102701.
25.
Wallis
,
A. M.
,
Denton
,
J. D.
, and
Demargne
,
A. A. J.
,
2001
, “
The Control of Shroud Leakage Flows to Reduce Aerodynamic Losses in a Low Aspect Ratio, Shrouded Axial Flow Turbine
,”
ASME J. Turbomach.
,
123
(
2
), pp.
334
341
.
26.
Pfau
,
A.
,
Kalfas
,
A. I.
, and
Abhari
,
R. S.
,
2007
, “
Making Use of Labyrinth Interaction Flow
,”
ASME J. Turbomach.
,
129
(
1
), pp.
164
174
.
27.
Rosic
,
B.
,
Denton
,
J. D.
, and
Curtis
,
E. M.
,
2007
, “
The Influence of Shroud and Cavity Geometry on Turbine Performance—an Experimental and Computational Study—Part 1: Shroud Geometry
,”
ASME
Paper No. GT2007-27769.
28.
Rosic
,
B.
,
Denton
,
J. D.
, and
Pullan
,
G.
,
2006
, “
The Importance of Shroud Leakage Modelling in Multistage Turbine Flow Calculations
,”
ASME J. Turbomach.
,
128
(
4
), pp.
699
707
.
29.
Rubechini
,
F.
,
Marconcini
,
M.
,
Arnone
,
A.
,
Cecchi
,
S.
, and
Daccà
,
F.
,
2007
, “
Some Aspects of CFD Modeling in the Analysis of a Low-Pressure Steam Turbine
,”
ASME
Paper No. GT2007-27235.
30.
Rubechini
,
F.
,
Schneider
,
A.
,
Arnone
,
A.
,
Cecchi
,
S.
, and
Garibaldi
,
P.
,
2012
, “
A Redesign Strategy to Improve the Efficiency of a 17-Stage Steam Turbine
,”
ASME J. Turbomach.
,
134
(
3
), p.
031021
.
31.
McGreeham
,
W. F.
, and
Ko
,
S. H.
,
1989
, “
Power Dissipation in Smooth and Honeycomb Labyrinth Seals
,”
ASME
Paper No. 89-GT-220.
32.
Paradiso
,
B.
,
Mora
,
A.
,
Dossena
,
V.
,
Gatti
,
G.
,
Nesti
,
A.
,
Arcangeli
,
L.
, and
Maceli
,
N.
,
2015
, “
Flow Evolution in a One and a Half Axial Steam Turbine Stage Under Different Operating Conditions
,”
ASME
Paper No. GT2015-43201.
33.
Paradiso
,
B.
,
Gaetani
,
P.
,
Mora
,
A.
,
Dossena
,
V.
,
Osnaghi
,
C.
,
Arcangeli
,
L.
,
Gerbi
,
F.
,
Maceli
,
N.
, and
Quadrelli
,
R.
,
2015
, “
Design and Operation of a Low Speed Test Turbine Facility
,”
11th European Turbomachinery Conference
, Madrid, Spain, Paper No. ETC2015-223.
34.
Persico
,
G.
,
Gaetani
,
P.
, and
Guardone
,
A.
,
2005
, “
Design and Analysis of New Concept Fast-Response Pressure Probes
,”
Meas. Sci. Technol.
,
16
(
9
), p.
1741
.
35.
Gaetani
,
P.
,
Persico
,
G.
,
Dossena
,
V.
, and
Osnaghi
,
C.
,
2006
, “
Investigation of the Flow Field in a High-Pressure Turbine Stage for Two Stator-Rotor Axial Gap—Part II: Unsteady Flow Field
,”
ASME J. Turbomach.
,
129
(
3
), pp.
580
590
.
36.
Schennach
,
O.
,
Woisetschlager
,
J.
,
Paradiso
,
B.
,
Persico
,
G.
, and
Gaetani
,
P.
,
2009
, “
Three Dimensional Clocking Effects in a One and a Half Stage Transonic Turbine
,”
ASME J. Turbomach.
,
132
(
1
), p.
011019
.
37.
Cumpsty
,
N. A.
, and
Horlock
,
J. H.
,
2006
, “
Averaging Nonuniform Flow for a Purpose
,”
ASME J. Turbomach.
,
120
(
1
), pp.
120
129
.
38.
Suresh
,
A.
,
Hofer
,
D. C.
, and
Tangirala
,
V. E.
,
2012
, “
Turbine Efficiency for Unsteady, Periodic Flows
,”
ASME J. Turbomach.
,
134
(
3
), p.
034501
.
39.
Van Zante
,
D. E.
,
Chen
,
J. P.
,
Hathaway
,
T. H.
, and
Randall
,
C.
,
2008
, “
The Influence of Compressor Blade Row Interaction Modeling on Performance Estimates From Time-Accurate, Multistage, Navier–Stokes Simulations
,”
ASME J. Turbomach.
,
130
(
1
), p. 011009.
40.
Sharma
,
O. P.
,
Butler
,
T. L.
,
Joslyn
,
H. D.
, and
Dring
,
R. P.
,
1985
, “
Three-Dimensional Unsteady Flow in an Axial Flow Turbine
,”
J. Propul. Power
,
1
(
1
), pp.
29
38
.
41.
Restemeier
,
M.
,
Jeschke
,
P.
,
Guendogdu
,
Y.
, and
Gier
,
J.
,
2012
, “
Numerical and Experimental Analysis of the Effect of Variable Blade Row Spacing in a Subsonic Axial Turbine
,”
ASME J. Turbomach.
,
135
(
2
), p.
021031
.
42.
Dring
,
R. P.
,
Joslyn
,
H. D.
,
Hardin
,
L. W.
, and
Wagner
,
J. H.
,
1982
, “
Turbine Rotor–Stator Interaction
,”
ASME J. Eng. Power
,
104
(
4
), pp.
729
742
.
You do not currently have access to this content.