LNG 펌프의 누설 유량 최소화를 위한 래버린스 실 형상의 수치적 연구

Abstract

In the submersible pump used in an LNG cargo, the leakage flow (gap flow) occurs between the pump rotor and the casing, and the pump efficiency decreases. The labyrinth-shaped pattern is applied between these gaps to decrease the leakage flow, which is called Labyrinth Seal. This research studied the difference in flow characteristics when liquefied methane which accounts for most LNG composition passes through labyrinth seals of different shapes using computational fluid dynamics (CFD). Four shape variables were considered: clearance size(s), cavity width(b), cavity height(g), and number of cavity(z). Parametric study was performed by changing only the input value of one variable without changing other variables within a limited range. As the gap of the labyrinth seal increased, the leakage flow rate increased. But the effect of the cavity-related variables was different. As a result of analyzing the effects of three cavity variables using full factorial design, they were found to be almost independent of each other. As the cavity width and number increase, the leakage flow rate decreases linearly. And the cavity height has a maximum leakage flow rate at one point, but has the smallest influence among all variables.