Experimental study on the effects of bristle diameter on the leakage and heat transfer characteristics of low-hysteresis brush seals

Low-hysteresis brush seals are widely recognized for their excellent performance and their ability to effectively reduce the hysteresis and stiffening characteristics inherent in conventional brush seals. Currently, there is a scarcity of studies on the impact of key structural parameters such as bristle diameter on leakage and frictional heating of low-hysteresis brush seals, while the interaction between bristle diameter and the pressure relief chamber’s friction-reducing function may induce leakage hysteresis and thermal response trends that are different from those of conventional brush seals. This study investigates the leakage and heat transfer characteristics and hysteretic behavior of a low-hysteresis brush seal configuration tested with three distinct bristle diameters. Experiments were performed using 0 – 10,000 – 0 rpm speed ascending and descending cycles under pressure differentials of 0.1 MPa and 0.15 MPa and inlet temperatures of 300 K and 350 K. The results show seals with larger bristle diameters exhibit higher leakage rates. However, they also show a greater reduction in leakage during the rotor speed ramp-up phase and a weaker hysteresis effect. Under a 0.1 MPa pressure differential, leakage decreases as inlet temperature increases, particularly in seals with larger bristle diameters, where the reduction reaches up to 11.6%. The frictional temperature rise between the bristle pack and the rotor is lower for seals with larger bristle diameters, with the difference in maximum rise reaching roughly 23K. A hysteresis effect is also evident in the frictional temperature rise, characterized by higher temperatures during the ramp-up phase at the same rotor speed. The maximum temperature difference observed under ambient conditions is approximately 20 K.