Classification And Characteristics Of Brush Seals
Mar 11, 2026| Based on their structural and functional characteristics, brush seals can be categorized into standard types, multi-stage types, and hybrid types that combine brush seals with other sealing mechanisms (such as brush-labyrinth seals).
Multi-stage brush seals face the issue of uneven pressure drop distribution across their stages, which can easily lead to premature seal failure. Studies indicate that in multi-stage brush seals, the pressure drop borne by each successive stage increases progressively (for instance, in a two-stage brush seal, the pressure drop contributions of the individual stages typically range from 32%–35% and 65%–68%, respectively). The primary cause of this phenomenon is the progressively increasing-and uneven-volumetric flow rate across the stages. By increasing the cross-sectional area of the flow channels in the downstream stages, the volumetric flow rate can be effectively reduced, thereby balancing the pressure drop across the stages and enhancing both seal performance and service life.
Hybrid brush seals (such as brush-labyrinth seals) leverage the advantages inherent in different sealing mechanisms. Fluid-structure interaction simulations demonstrate that, under identical operating conditions, the leakage rate of such hybrid designs can be reduced by approximately 18% compared to pure brush seal structures. The airflow vortices generated within their flow fields serve to dissipate a portion of the gas energy and reduce leakage velocity, thereby endowing the seal with a certain degree of adaptability across a range of differential pressure conditions.
Overall, brush seals offer several distinct advantages, including low requirements for installation precision, high efficiency, and minimal leakage. Practical applications-such as in the retrofitting of steam turbines at power plants-have demonstrated that these seals can effectively boost turbine cylinder efficiency, reduce coal consumption, and generate significant economic benefits.
Furthermore, various specialized structural designs have been developed to optimize performance; for instance, brush seal designs featuring bent bristle sections allow for the simultaneous achievement of low bristle stiffness and minimal radial structural footprint.