Numerical and experimental analyses were carried out to investigate the static characteristics of liquid annular seals with helical grooves in a seal stator. In the numerical analysis, the momentum equations with turbulent coefficients and the continuity equation, which were averaged across the film thickness, were numerically solved to obtain the leakage flow rate and the pressure distributions in the seal clearance. To accurately define the location of the step between the groove and the land regions in the calculation domain, these governing equations were expressed using an oblique coordinate system in which the directions of coordinate axes coincided with the circumferential direction and the direction along the helical grooves. The numerical analysis included the effects of both fluid inertia and energy loss due to expansion during the passage of fluid from the land region to the helical groove region and that due to contraction from the groove region to the land region. In the experimental analysis, the leakage flow rate and the fluid-film pressure distributions in the seal clearance were measured for the helically grooved seals with different helix angles of the helical groove. The numerical results of leakage flow rate and pressure distributions agree reasonably with the experimental results, which demonstrates the validity of the numerical analysis. The leakage flow rate of the helically grooved seals was influenced by two factors: fluid energy loss during passage through the step between the groove and the land, and the pumping effect by which the spinning motion of the rotor pushes the flow back upstream along the helical grooves. Under a low range of rotor spinning velocity, the leakage flow rate decreased with helix angle because the effect of fluid energy loss in the steps was significant. By contrast, under a high range of spinning velocity, the quantitative difference in the leakage flow rate due to the helix angle decreased compared to that under a low range because the reduction in the leakage flow rate due to the pumping effect was pronounced for a larger helix angle. The effects of helix angle and rotor spinning velocity on the leakage flow rate are explained qualitatively using a simplified model.

References

References
1.
Nitanai
,
A.
,
Sawa
,
T.
, and
Nakazima
,
T.
,
2010
,
Sealing Technology—The Solution of Leakage Trouble
,
Techno System
, Tokyo, Japan, pp.
458
463
.
2.
Kim
,
C. H.
, and
Childs
,
D. W.
,
1987
, “
Analysis for Rotordynamic Coefficients of Helically-Grooved Turbulent Annular Seals
,”
ASME J. Tribol.
,
109
(
1
), pp.
136
143
.
3.
Iwatsubo
,
T.
,
Ishimaru
,
H.
, and
Uchida
,
T.
,
1999
, “
A Study on Static and Dynamic Characteristics of Spiral-Grooved Seals
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
,
65
(
632
), pp.
1395
1402
.
4.
Kanki
,
H.
, and
Kawakami
,
T.
,
1988
, “
Experimental Study on the Static and Dynamic Characteristics of Screw Grooved Seals
,”
ASME J. Vib., Acoust., Stress Reliab. Des.
,
110
(
3
), pp.
326
331
.
5.
Childs
,
D. W.
,
Nolan
,
S. A.
, and
Kilgore
,
J. J.
,
1990
, “
Test Results for Turbulent Annular Seals Using Smooth Rotors and Helically Grooved Stators
,”
ASME J. Tribol.
,
112
(
2
), pp.
254
258
.
6.
Iwatsubo
,
T.
,
Sheng
,
B. C.
, and
Ono
,
M.
,
1990
, “
Experiment of Static and Dynamic Characteristics of Spiral Grooved Seals
,”
Rotordynamic Instability Problems in High-Performance Turbomachinery
, Austin, TX, May 21–23, pp.
223
233
.https://ntrs.nasa.gov/search.jsp?R=19920005143
7.
Hirs
,
G. G.
,
1973
, “
A Bulk-Flow Theory for Turbulence in Lubricant Films
,”
ASME J. Lubr. Technol.
,
95
(
2
), pp.
137
146
.
8.
Kaneko
,
S.
,
Saito
,
T.
,
Koyanagi
,
T.
, and
Ito
,
S.
,
2001
, “
Effects of Inlet Swirl Velocity on Static Characteristics of Annular Plain Seals (Numerical Analysis Based on Averaged Navier–Stokes Equations With Turbulent Coefficients)
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
,
67
(
656
), pp.
1123
1130
.
9.
Kaneko
,
S.
,
Saito
,
T.
,
Koyanagi
,
T.
, and
Ito
,
S.
,
2001
, “
Effects of Inlet Swirl Velocity on Dynamic Characteristics of Annular Plain Seals (Numerical Analysis Based on Averaged Navier–Stokes Equations With Turbulent Coefficients)
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
,
67
(
656
), pp.
1131
1138
.
10.
Kaneko
,
S.
,
Taura
,
H.
,
Ueda
,
N.
, and
Henmi
,
K.
,
2008
, “
Static Characteristics of Liquid Annular Seals With Square-Hole Pattern
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
,
74
(
745
), pp.
79
89
.
11.
Kaneko
,
S.
,
Taura
,
H.
,
Ueda
,
N.
, and
Henmi
,
K.
,
2008
, “
Dynamic Characteristics of Liquid Annular Seals With Square-Hole Pattern
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
,
74
(
748
), pp.
29
37
.
12.
Yang
,
B. S.
,
Iwatsubo
,
T.
, and
Kawai
,
R.
,
1984
, “
A Study on the Dynamic Characteristics of Pump Seal (2nd Report, In Case of Parallel Grooved Seal)
,”
Trans. Jpn. Soc. Mech. Eng., Ser. C
,
50
(
460
), pp.
2319
2329
.
13.
Arghir
,
M.
, and
Frene
,
J.
,
2004
, “
A Bulk-Flow Analysis of Static and Dynamic Characteristics of Eccentric Circumferentially-Grooved Liquid Annular Seals
,”
ASME J. Tribol.
,
126
(
2
), pp.
316
325
.
14.
Hori
,
Y.
,
2006
,
Hydrodynamic Lubrication
,
Springer-Verlag
,
Tokyo, Japan
, pp.
204
210
.
15.
Constantinescu
,
V. N.
,
1976
, “
Pressure Drop due to Inertia Force in Step Bearings
,”
ASME J. Lubr. Technol.
,
98
(
1
), pp.
167
174
.
16.
Kaneko
,
S.
,
Ikeda
,
T.
,
Saito
,
T.
, and
Ito
,
S.
,
2003
, “
Experimental Study on Static and Dynamic Characteristics of Liquid Annular Convergent-Tapered Damper Seals With Honeycomb Roughness Pattern
,”
ASME J. Tribol.
,
125
(
3
), pp.
592
599
.
17.
ANSI/ASME
,
1986
, “
Measurement Uncertainty—Part 1
,” American Society of Mechanical Engineers, New York, Standard No. PTC 19.1-1985.
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