Experimental Investigation on Leakage and Frictional Heat Generation Characteristics of Low Hysteresis Brush Seals

Abstract

Low hysteresis brush seals are frequently used in systems operating at a high speed in environments featuring a high temperature and pressure. The high-speed rotor comes into contact with the bottom end of the bristles of the brush seal in such scenarios to generate a significant amount of frictional heat, which directly affects its sealing performance and service life, while a high temperature can increase the magnitude of its friction-induced heat. In this study, we report the cyclical testing of a low hysteresis brush seal while increasing and decreasing the speed of the rotor under varying differences in the pressure and temperature. We focus on the characteristics of leakage, hysteresis effect, and temperature rise at the bottom end of the bristles of the brush seal owing to frictional heat. The results showed that the volume of leakage increased at a high temperature under a strong hysteresis effect and a small rise in the temperature. Moreover, as the speed of the rotor exceeded 6000 rpm, the temperature of the system increased rapidly owing to frictional heat. During the speed decrease stage, the temperature rise decreased sharply and then gradually until it became nearly constant. The hysteresis effect resulted in a lower temperature rise during the decrease in the speed of the rotor compared with that during an increase in its speed. While the low hysteresis structure can effectively reduce hysteresis effect compared with that of the conventional brush seal, it induced greater leakage. It is necessary to choose a pressure relief chamber of a suitable size to minimize leakage. Furthermore, the low hysteresis brush seal exhibited a smaller friction temperature rise than the conventional seal, where this is beneficial for its service life.