Abstract

Cavity separation baffles can decrease the circumferential swirl intensity of labyrinth seals and increase the seals' rotordynamic characteristics. Compared with conventional baffles, the bristle packs of brush seal baffles can contact the rotor directly, thereby further reducing the swirl intensity of the seal cavity. This paper, using the numerical model combining a multifrequency elliptical whirling orbit model, a porous medium model, and transient Reynolds-averaged Navier–Stokes (RANS) solutions, compares the leakage flow and rotordynamic characteristics of a labyrinth seal with brush-seal baffles (LSBSB) and a labyrinth seal with conventional baffles (LSCB). Ideal air flows into the seal at an inlet preswirl velocity of 0 m/s (or 60 m/s or 100 m/s), total pressure of 690 kPa, and temperature of 14 °C. The outlet static pressure is 100 kPa and the rotational speed is 7500 r/min (surface speed of 66.8 m/s) or 15,000 r/min (surface speed of 133.5 m/s). Numerical results show that the LSBSB possesses the slightly less leakage flow rate than the LSCB due to the flow resistance of the bristle pack to the fluid. Compared with the LSCB, the LSBSB shows a higher positive effective stiffness (Keff) at all considered vibration frequencies and a higher effective damping (Ceff) for most vibration frequencies. What is more, the crossover frequency (fc0) of the LSBSB is significantly lower than that of the LSCB, which means that the LSBSB has a wider frequency range offering positive effective damping. The increasing inlet preswirl velocity and rotational speed only slightly affect the Keff for both seals. The Ceff of two seals decreases as the inlet preswirl velocity rises, especially for the LSCB. The Ceff of the LSCB slightly decreases because of the increasing rotational speed. In contrast, the Ceff of the LSBSB is not sensitive to the changes in rotational speed. In a word, the LSBSB possesses superior rotordynamic performance to the LSCB. Note that this work also investigates the leakage flow and rotordynamic characteristics a labyrinth seal with inclined baffles (LSIB) under the condition of u0 = 60 m/s and n = 15,000 r/min. The inclined baffles of the LSIB are same as the backing plates of LSBSB baffles. The LSIB has rotordynamic coefficients almost equal to the LSCB. Hence, the reason why the LSBSB possesses better rotordynamic performance than that of the LSCB is the flow resistance of bristle packs of brush seal baffles, not the inclination direction variation of baffles.

References

1.
Chupp
,
R. E.
,
Hendricks
,
R. C.
,
Lattime
,
S. B.
, and
Steinetz
,
B. M.
,
2006
, “
Sealing in Turbomachinery
,”
J. Propul. Power
,
22
(
2
), pp.
313
349
.10.2514/1.17778
2.
Li
,
Z.
,
Li
,
J.
, and
Yan
,
X.
,
2013
, “
Multiple Frequencies Elliptical Whirling Orbit Model and Transient RANS Solution Approach to Rotordynamic Coefficients of Annual Gas Seals Prediction
,”
ASME J. Vib. Acoust.
,
135
(
3
), p.
031005
.10.1115/1.4023143
3.
Benckert
,
H.
, and
Wachter
,
J.
,
1980
, “
Flow Induced Spring Constants of Labyrinth Seals
,”
Proceedings of the Second International Conference
,
ImechE, Vibrations in Rotating Machinery
, Cambridge, UK, Sept. 2–4, pp.
53
63
.
4.
Childs
,
D. W.
, and
Vance
,
J. M.
,
1997
, “
Annular Seals and the Rotordynamics of Compressors and Turbines
,”
Proceedings of the 26th Turbomachinery Symposium
,
Texas A&M University
, College Station, TX, Sept. 14–18, pp.
201
220
. https://oaktrust.library.tamu.edu/handle/1969.1/163429
5.
Vance
,
J. M.
, and
Schultz
,
R. R.
,
1993
, “
A New Damper Seal for Turbomachinery
,”
14th Biennial ASME Conference on Vibration and Noise
, Albuquerque, NM, Sept. 19–22, pp. 139–148. https://www.tib.eu/en/search/id/BLCP%3ACN000551491/A-New-Damper-Seal-for-Turbomachinery/
6.
Li
,
Z.
,
Li
,
J.
,
Feng
,
Z.
,
Yang
,
J.
,
Yang
,
R.
, and
Shi
,
L.
,
2011
, “
Numerical Investigations on the Leakage Flow Characteristics of Pocket Damper Seals
,”
ASME
Paper No. GT2011-45114.10.1115/GT2011-45114
7.
Li
,
Z.
,
Li
,
J.
,
Yan
,
X.
, and
Feng
,
Z.
,
2012
, “
Numerical Investigations on the Leakage Flow Characteristics of Pocket Damper Labyrinth Seals
,”
Proc. IMechE Part A: J. Power Energy
,
226
(
7
), pp.
932
948
.10.1177/0957650912451410
8.
Vance
,
J. M.
, and
Li
,
J.
,
1996
, “
Test Results of a New Damper Seal for Vibration Reduction in Turbomachinery
,”
ASME J. Eng. Gas Turbines Power
,
118
(
4
), pp.
843
846
.10.1115/1.2817004
9.
Ertas
,
B. H.
,
Delgado
,
A.
, and
Vannini
,
G.
,
2012
, “
Rotordynamic Force Coefficients for Three Types of Annular Gas Seals With Inlet Preswirl and High Differential Pressure Ratio
,”
ASME J. Eng. Gas Turbines Power
,
134
(
4
), p.
042503
.10.1115/1.4004537
10.
Ertas
,
B.
,
Gamal
,
A.
, and
Vance
,
J.
,
2006
, “
Rotordynamic Force Coefficients of Pocket Damper Seals
,”
ASME J. Turbomach.
,
128
(
4
), pp.
725
737
.10.1115/1.2221327
11.
Li
,
J.
,
Kushner
,
F.
, and
Choudhury
,
P. D.
,
2002
, “
Experimental Evaluation of Slotted Pocket Gas Damper Seals on a Rotating Test Rig
,”
ASME
Paper No. GT2002-30634.10.1115/GT2002-30634
12.
Ertas
,
B. H.
, and
John
,
V.
,
2007
, “
Rotordynamic Force Coefficients for a New Damper Seal Design
,”
ASME J. Tribol.
,
129
(
2
), pp.
365
374
.10.1115/1.2464138
13.
Iwatsubo
,
T.
,
1980
, “
Evaluation of Instability of Forces of Labyrinth Seals in Turbines or Compressors
,”
Workshop on Rotordynamic Instability Problems in High-Performance Turbomachinery
,
Texas A&M University
, pp.
139
167
, NASA Conference Publication No. 2133.https://www.researchgate.net/publication/23621180_Evaluation_of_instability_forces_of_labyrinth_seals_in_turbines_or_compressors
14.
Cangioli
,
F.
,
Pennacchi
,
P.
,
Vannini
,
G.
, and
Ciuchicchi
,
L.
,
2018
, “
Effect of Energy Equation in One Control-Volume Bulk-Flow Model for the Prediction of Labyrinth Seal Dynamic Coefficients
,”
Mech. Syst. Signal Process.
,
98
(
2018
), pp.
594
612
.10.1016/j.ymssp.2017.05.017
15.
Saba
,
D.
,
Forte
,
P.
, and
Vannini
,
G.
,
2015
, “
Review and Upgrade of a Bulk Flow Model for the Analysis of Honeycomb Gas Seals Based on New High Pressure Experimental Data
,”
Strojniški Vestnik J. Mech. Eng.
,
60
(
5
), pp.
321
330
.10.5545/sv-jme.2014.1835
16.
Childs
,
D. W.
,
Shin
,
Y. S.
, and
Seifert
,
B.
,
2008
, “
A Design to Improve the Effective Damping Characteristics of Hole-Pattern-Stator Annular Gas Seals
,”
ASME J. Eng. Gas Turbines Power
,
130
(
1
), p.
012505
.10.1115/1.2771242
17.
Li
,
J.
,
San AndréS
,
L.
, and
Vance
,
J.
,
1999
, “
A Bulk-Flow Analysis of Multiple-Pocket Gas Damper Seals
,”
ASME J. Eng. Gas Turbines Power
,
121
(
2
), pp.
355
363
.10.1115/1.2817128
18.
Li
,
J.
,
Aguilar
,
R.
,
San Andres
,
L.
, and
Vance
,
J. M.
,
2000
, “
Dynamic Force Coefficients of a Multiple-Blade, Multiple-Pocket Gas Damper Seal: Test Results and Predictions
,”
ASME J. Tribol.
,
122
(
1
), pp.
31
322
.10.1115/1.555360
19.
Cangioli
,
F.
,
Vannini
,
G.
, and
Chirathadam
,
T.
,
2020
, “
A Novel Bulk-Flow Model for Pocket Damper Seals
,”
ASME J. Eng. Gas Turbines Power
,
142
(
1
), p.
011012
.10.1115/1.4045000
20.
Nordmann
,
R.
,
Dietzen
,
F. J.
, and
Weiser
,
H. P.
,
1989
, “
Calculation of Rotordynamic Coefficients and Leakage for Annular Gas Seals by Means of Finite Difference Techniques
,”
ASME J. Tribol.
,
111
(
3
), pp.
545
552
.10.1115/1.3261964
21.
Pugachev
,
A. O.
,
Kleinhans
,
U.
, and
Gaszner
,
M.
,
2012
, “
Prediction of Rotordynamic Coefficients for Short Labyrinth Gas Seals Using Computational Fluid Dynamics
,”
ASME J. Eng. Gas Turbines Power
,
134
(
6
), p.
062501
.10.1115/1.4005971
22.
Zhang
,
M.
,
Yang
,
J.
,
Xu
,
W.
, and
Xia
,
Y.
,
2017
, “
Leakage and Rotordynamic Performance of a Mixed Labyrinth Seal Compared With That of a Staggered Labyrinth Seal
,”
J. Mech. Sci. Technol.
,
31
(
5
), pp.
2261
2277
.10.1007/s12206-017-0423-7
23.
Li
,
J.
,
Li
,
Z.
, and
Feng
,
Z.
,
2012
, “
Investigations on the Rotordynamic Coefficients of Pocket Damper Seals Using the Multifrequency, One-Dimensional, Whirling Orbit Model and RANS Solutions
,”
ASME J. Eng. Gas Turbines Power
,
134
(
10
), p.
102510
.10.1115/1.4007063
24.
Li
,
Z.
,
Li
,
J.
, and
Feng
,
Z.
,
2015
, “
Numerical Investigations on the Leakage and Rotordynamic Characteristics of Pocket Damper Seals Part I: Effects of Pressure Ratio, Rotational Speed and Inlet Preswirl
,”
ASME J. Eng. Gas Turbines Power
,
137
(
3
), p.
032503
.10.1115/1.4028373
25.
Li
,
Z.
,
Li
,
J.
, and
Feng
,
Z.
,
2015
, “
Numerical Investigations on the Leakage and Rotordynamic Characteristics of Pocket Damper Seals-Part II: Effects of Partition Wall Type, Partition Wall Number, and Cavity Depth
,”
ASME J. Eng. Gas Turbines Power
,
137
(
3
), p.
032504
.10.1115/1.4028374
26.
Li
,
Z.
,
Li
,
J.
, and
Feng
,
Z.
,
2016
, “
Numerical Comparison of Rotordynamic Characteristics for a Fully Partitioned Pocket Damper Seal and a Labyrinth Seal With High Positive and Negative Inlet Preswirl
,”
ASME J. Eng. Gas Turbines Power
,
138
(
4
), p.
042505
.10.1115/1.4031545
27.
Li
,
Z.
,
Li
,
J.
, and
Feng
,
Z.
,
2016
, “
Comparisons of Rotordynamic Characteristics Predictions for Annular Gas Seals Using the Transient Computational Fluid Dynamic Method Based on Different Single-Frequency and Multifrequency Rotor Whirling Models
,”
ASME J. Tribol.
,
138
(
1
), p.
011701
.10.1115/1.4030807
28.
Griebel
,
C.
,
2019
, “
Impact Analysis of Pocket Damper Seal Geometry Variations on Leakage Performance and Rotordynamic Force Coefficients Using Computational Fluid Dynamics
,”
ASME J. Eng. Gas Turbines Power
,
141
(
4
), p.
041024
.10.1115/1.4040749
29.
Pugachev
,
A. O.
, and
Deckner
,
M.
,
2010
, “
CFD Prediction and Test Results of Stiffness and Damping Coefficients for Brush-Labyrinth Gas Seals
,”
ASME
Paper No. GT2010-22667.10.1115/GT2010-22667
30.
Laos
,
H. E.
,
Vance
,
J. M.
, and
Buchanan
,
S. E.
,
2000
, “
Hybrid Brush Pocket Damper Seals for Turbomachinery
,”
ASME J. Eng. Gas Turbines Power
,
122
(
2
), pp.
330
336
.10.1115/1.483211
31.
Pugachev
,
A. O.
,
Griebel
,
C.
,
Tibos
,
S.
, and
Charnley
,
B.
,
2016
, “
Performance Analysis of Hybrid Brush Pocket Damper Seals Using Computational Fluid Dynamics
,”
ASME
Paper No. GT2016-57418.10.1115/GT2016-57418
32.
Sun
,
D.
,
Wang
,
S.
,
Xiao
,
Z.
,
Meng
,
J.
,
Wang
,
X.
, and
Zheng
,
T.
,
2015
, “
Measurement Versus Predictions of Rotordynamic Coefficients of Seal With Swirl Brakes
,”
Mech. Mach. Theory
,
94
(
2015
), pp.
188
199
.10.1016/j.mechmachtheory.2015.08.009
33.
Helm
,
P.
,
Pugachev
,
A.
, and
Neef
,
M.
,
2008
, “
Breaking the Swirl With Brush Seals-Numerical Modeling and Experimental Evidence
,”
ASME
Paper No. GT2008-50257.10.1115/GT2008-50257
34.
Vance
,
J.
,
Zeidan
,
F.
, and
Murphy
,
B.
,
2010
,
Machinery Vibration and Rotordynamics
, Chap. 6,
Wiley
,
New York
.
35.
Li
,
J.
,
Qiu
,
B.
, and
Feng
,
Z.
,
2012
, “
Experimental and Numerical Investigations on the Leakage Flow Characteristics of the Labyrinth Brush Seal
,”
ASME J. Eng. Gas Turbines Power
,
134
(
10
), p.
102509
.10.1115/1.4007062
36.
Chew
,
J. W.
, and
Hogg
,
S. I.
,
1997
, “
Porosity Modeling of Brush Seals
,”
ASME J. Tribol.
,
119
(
4
), pp.
769
775
.10.1115/1.2833883
37.
Ergun
,
S.
,
1952
, “
Fluid Flow Through Packed Columns
,”
Chem. Eng. Prog.
,
48
(
2
), pp.
89
94
.http://dns2.asia.edu.tw/~ysho/YSHO-English/1000%20CE/PDF/Che%20Eng%20Pro48,%2089.pdf
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