래버린스 씰 형상 수정을 통한 회전체 동적 안정성 개선

초록

This paper presents the research on dynamic stability improvement of a rotor-seal system by modifying a labyrinth seal geometry. The stability improvement aims to increase the separation margin of a rotor system and make a better unbalance response in the operating speed range. The rotor system is composed of a shaft, labyrinth seal, disk, and rigid supports. A finite element-based flexible rotor model was used for the rotordynamic analysis. Due to the complicated rotordynamic characteristic of the labyrinth seal, the multi-objective genetic algorithm has been adopted for seal geometry modification. The rotordynamic coefficients of the labyrinth seal are calculated using a 1-control-volume bulk flow model and then added to the rotordynamic equation. The number of the seal teeth, seal clearance, teeth pitch, and teeth height is selected as chromosome of the genetic algorithm. The objective function is the leakage flow rate, separation margin, and unbalance response. In the optimal seal geometry, (a) the leakage flow rate is decreased, (b) the separation margin is above 15 %, and (c) the maximum unbalance response amplitude does not exceed the clearance. In contrast, the separation margin of poorly designed seals is less than 10 %.