Numerical Investigation on the Leakage Flow and Rotordynamic Characteristics of Brush-Labyrinth Seal[J]. 2019, 53(3): 28-35.
DOI:
Numerical Investigation on the Leakage Flow and Rotordynamic Characteristics of Brush-Labyrinth Seal[J]. 2019, 53(3): 28-35.DOI: 10.7652/xjtuxb201903005.
Numerical Investigation on the Leakage Flow and Rotordynamic Characteristics of Brush-Labyrinth Seal
To evaluate the sealing performance of brush-labyrinth seal and the effect on the rotor stability under eccentric whirl condition
a numerical method for investigating the leakage and rotordynamic characteristics of brush-labyrinth seal was presented based on the whirling rotor method and nonlinear Darcian porous medium model. The leakage flow characteristics and rotordynamic coefficients of brush-labyrinth seal under different working conditions including four pressure ratios(1.96
3
4.49
6.9)
five inlet preswirl velocities(-50
-30
0
30
50 m/s)and four rotor spinning speeds(3×10
3
、7.5×10
3
、1.5×10
4
、2×10
4
r/min)were studied. The influences of pressure ratio
inlet preswirl velocity and spinning speed on the brush-labyrinth seal leakage and rotordynamic characteristics were studied. The leakage and rotordynamic coefficients of brush-labyrinth seal were compared with the numerical results of traditional labyrinth seal. The results show that the leakage rate of brush-labyrinth seal is significantly lower than that of labyrinth seal. The effective clearance of the brush-labyrinth seal is only 25.5% of that in labyrinth seal when the pressure ratio is 6.9. The direct stiffness of the brush-labyrinth seal increases with the pressure ratio and the absolute value of the inlet preswirl
and does not change significantly with the change of the rotor spinning speed. The effective damping decreases with the increase of the inlet preswirl and the rotor spinning speed
and the bristle pack can act as a swirl brake. Compared with labyrinth seal
the cross-coupled stiffness and effective damping of brush-labyrinth seal are insensitive to changes of operation conditions and the direct stiffness of the brush-labyrinth seal is large in the whole studied working conditions
so the critical speed is higher. The sealing performance of brush-labyrinth seal is superior to that of labyrinth seal and the effective damping of brush-labyrinth is relatively high at high positive preswirl velocity or low rotor spinning speed
so the rotor system is more stable.
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references
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