Brush Seal Technology: Challenges And Improvements

The technical challenges facing brush seals include the hysteresis effect, which leads to increased leakage and exacerbated friction and wear. Under high pressure differentials, the brush bristles are prone to irreversible deformation and structural degradation. Furthermore, multi-stage brush seals suffer from issues regarding uneven inter-stage pressure drops, which negatively impact seal service life.

To address these challenges, various structural design improvements have been proposed. Low-hysteresis designs-such as brush rings featuring grooved backing plates-have been adopted to reduce contact pressure and mitigate the hysteresis effect. Six novel brush seal configurations have been introduced to resolve the issues of high leakage rates and short service life associated with traditional designs. By modifying the bristle structure-for instance, by incorporating bent sections-it is possible to reduce bristle stiffness and minimize the required radial clearance. The introduction of movable baffles serves to reduce the relative velocity between the bristles and the rotor, thereby extending the range of applicable pressure differentials. Hybrid brush seal configurations-such as brush-labyrinth seals-can effectively reduce leakage rates and enhance adaptability to varying pressure differential conditions.