The rotating and thermal effects on sealing performance were analyzed and the calculation model of axial lateral straight-through labyrinth seal was established, in order to explore the sealing mechanism of high-speed gearbox with mixed media of lubricating oil and ideal gas. The influences of structure deformation and flow field on the sealing performance were also studied, which were induced by the rotating and thermal effects. The results reveal that the rotating and thermal effects can reduce the sealing gap. Nevertheless, the thermal-effect-induced expansive deformation exceeded the rotating-effect-induced centrifugal deformation by one order of magnitude. In addition, the rotation speed had a threshold value (4 000 r/min). When the rotor rotation speed exceeded this threshold, the leakage loss of labyrinth seal decreased significantly. Compared with the condition without rotation, the leakage loss decreased 18.5% under the rotation speed of 10 000 r/min. At the same time, the leakage loss increased linearly with the increment of lubricating oil temperature and the decrease of oil viscosity. When the oil temperature was at 140 °C, the leakage loss increased 58.6% in comparison with that at 40 °C. The flow filed caused by rotating and thermal effects is the major factor affecting the leakage performance of gearbox sealing system, while the structure deformation is the secondary factor.
Yu ZHANG,Kai-lin ZHANG,Yuan YAO. Impact of rotating and thermal effects on leakage performance of gearbox with axial labyrinth seal. Journal of ZheJiang University (Engineering Science), 2019, 53(9): 1656-1662.
Fig.1Structure configuration of bilateral cavities straight through labyrinth seal
t/ °C
υ/（mm2·s?1）
t/ °C
υ/（mm2·s?1）
40
116
120
5.6
80
21.8
140
2.9
100
16.6
?
?
Tab.1Kinetic viscosity of lubricating oil under different temperatures
Fig.2Relation of oil leakage loss and grid number
Fig.3Discharge coefficient comparison of simulated and experimental results under different seal clearance widths
Fig.4Centrifugal deformation of rotor under different rotation speeds and radii
t/ °C
λ/（°C?1）
t/ °C
λ/（°C?1）
0
10.76
100
11.53
50
11.12
150
11.88
Tab.2Linear thermal-expansion coefficients of material Q345
Fig.5Expansive deformation of rotor under differenttemperature and radii
Fig.6Relation of seal gap ratio and leakage loss ratio
Fig.7Curve for lubricating oil leakage loss and leakage loss ratio under different rotation speeds and radii
Fig.8Curves for oil leakage loss and leakage loss ratio under different oil temperatures
n/（r·min?1）
r1/%
r2/%
r/%
0
0
0
0
2 000
?0.13
?0.52
?0.65
4 000
?0.18
?1.44
?1.62
6 000
?0.46
?3.86
?4.32
8 000
?0.76
?10.81
?11.57
10 000
?1.14
?17.31
?18.45
Tab.3Lubricating oil leakage loss under different rotation speeds
t/ °C
r1/%
r2/%
r/%
40
0
0
0
60
?6.99
32.63
25.64
80
?13.80
52.49
38.69
100
?17.12
63.54
46.42
120
?20.41
75.55
55.14
140
?24.66
83.29
58.63
Tab.4Lubricating oil leakage loss under different oil drops temperature
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