Experimental and Numerical Investigations on the Leakage Flow Characteristics of Labyrinth Brush Seals

Due to excellent sealing performance and strong adaptability to rotor excursions, brush seals are widely used in turbomachinery to control the leakage flow through rotor-stator clearances. The present paper experimentally and numerically investigated the leakage flow characteristics of a labyrinth seal and two types of single-stage labyrinth brush seals at the rotational speed of 0∼3000 r/min and the pressure ratio of 1.1∼2. The single-stage labyrinth brush seal has a radial clearance (c) of 0.7 mm or 0.8 mm between the bristle pack and the rotor. The results show that the sealing performance of labyrinth brush seals is superior to that of the labyrinth seal. Leakage flow rates of seals increase with the increase of the pressure ratio and the radial clearance (c). Leakage hysteresis effect of the labyrinth brush seal decreases with the increasing rotational speed. The radial pressure difference between the upper and lower surfaces of the bristle pack and the axial pressure difference between the upstream and downstream surfaces increase due to the increase of the pressure ratio and the decrease of the radial clearance (c), and thus the blow down effect and the degree of axial bending of the bristle pack increase. This work provides a reference for the design and leakage characteristics analysis of labyrinth brush seals. © 2020, Science Press. All right reserved.