Brush Seal Performance Parameters and Testing

The performance evaluation of brush seals involves parameters such as leakage rate, hysteresis characteristics, contact force between the brush bristles and the rotor, and friction and wear. Numerical simulation serves as a crucial method for investigating brush seal performance. A numerical model for the hysteresis characteristics of brush seals-developed using the finite element software ABAQUS-incorporates contact interactions among the bristles, as well as between the bristles and the backing plate and rotor; furthermore, damping is introduced to enhance convergence. The study indicates that increasing the pressure differential and bristle diameter intensifies hysteresis, whereas increasing the bristle inclination angle attenuates it; the free length of the bristles has only a limited impact on hysteresis. Bristle diameter is the pivotal factor determining the contact force between the bristles and the rotor, while the bristle inclination angle also exerts a certain influence on the maximum contact force. A fluid-structure interaction model can be employed to analyze the effects of parameters-such as pressure differential and bristle geometric properties-on the seal's flow field and bristle deformation.

Experimental testing constitutes an indispensable means for validating numerical models and acquiring authentic performance data. To investigate the dynamic characteristics of brush bristles, an experimental apparatus comprising an air intake system, a sealing system, and a measurement system can be constructed; this setup is equipped with a high-speed video measurement system to observe bristle deformation, displacement, stratification, and vibration phenomena under the influence of high-pressure airflow. Bristle vibration phenomena predominantly occur in regions where bristle density is relatively sparse, and the intensity of such vibrations increases in tandem with the pressure ratio. Regarding the friction and wear characteristics of brush seals, specialized experimental test rigs can be utilized to measure bristle friction force, friction torque, and radial force-thereby enabling the calculation of the friction coefficient-while the extent of bristle wear can be quantified using the gravimetric method.