Conjugate heat transfer analysis on the action mechanism of centrifugal force and centrifugal buoyancy in staggered labyrinth seals

Abstract

The heat transfer characteristics of smooth and honeycomb staggered labyrinth seals were investigated using the conjugate heat transfer method. Three pressure ratios (π = 1.2, 1.6, and 2.0), three rotational speeds (RPM = 0, 10,000, and 20,000), and two wall-to-fluid temperature ratios (TR = 0.4 and −0.67) are considered to explore the influence of centrifugal force and centrifugal buoyancy. The results indicate that the heat transfer coefficient of staggered labyrinth seals increases with pressure ratio due to the increased flow velocity and the thinner boundary layer. As a result of the interaction of inertia force and centrifugal force, some enhancement positions of heat transfer coefficient shift slightly. Notably, centrifugal buoyancy has a negative impact on heat transfer at TR = −0.67, but a positive impact at TR = 0.4. When TR = −0.67, there is a peak of the heat transfer coefficient with increased rotational speed due to centrifugal buoyancy. In addition, the heat transfer coefficient at TR = −0.67 is lower than that at TR = 0.4, especially at high rotational speeds. It is proposed that heat transfer correlations be developed by incorporating the Taylor number and rotating Grachev number.