Experimental investigation of leakage performance and bristle mechanical characteristics of brush seals under rotational conditions

Brush seals have gained prominence as an effective alternative to conventional labyrinth seals in gas turbine engines due to their superior sealing performance. Their flexible bristles accommodate rotor eccentricity, enhancing sealing adaptability. However, under high pressure load and high rotor rotational speeds, the bristles are susceptible to severe elastic deformation, which can lead to hysteresis effects, instability, and degradation in sealing efficiency. This study designs a high-speed visual brush seal rig and combines it with fluid–structure interaction simulations to investigate the bristle mechanics and leakage behavior under rotational speeds ranging from 0 to 6600rpm. The effects of front plate and radial clearance between bristle tip and rotor on leakage, windage heating, and hysteresis are then systematically examined. First, for brush seals without a front plate, the results indicate that higher rotational speeds reduce leakage but increase windage heating and suppress the hysteresis behavior of the bristles. Under operating conditions of 3000rpm and a pressure ratio of 1.55, significant bristle deformation is observed, with the radial clearance increasing by approximately 0.08mm. When the pressure ratio decreases to 1.34, a closure effect emerges in the rear rows of bristles, accompanied by a distinct stratification phenomenon. Second, the introduction of a long front plate alters the airflow direction, increases the normal aerodynamic force on the bristles, reduces the axial force, and weakens the sealing performance, thereby elevating the leakage risk. Finally, while increasing the radial clearance exacerbates leakage, it contributes to lower windage heating and mitigates bristle hysteresis.