Computational Methodology and Experimental Validation of Porous Medium Resistance Coefficients for Two-Stage Brush Seal Based on the Three-Dimensional Tube Bundle Model

To address the problems where the resistance coefficients of the two-stage brush seal porous medium model rely on experimental calibration and the resistance characteristics of each stage are difficult to distinguish, this paper proposes a method without experimental calibration for determining the porous medium resistance coefficients of two-stage brush seals. By combining the three-dimensional tube bundle model with porous medium theory and Hagen–Poiseuille flow theory, the viscous and inertial resistance coefficients of each stage were derived. Two-stage brush seal specimens with three backing plate protection heights were manufactured, and a leakage flow experimental setup was constructed to verify the proposed method. Differences in resistance coefficients between the two stages and the effect of backing plate protection height on resistance coefficients were investigated. Results show that the calculated leakage rates from the porous medium model agree well with experimental data, verifying the accuracy of the proposed solution method. In the two-stage brush seal, both the viscous and inertial resistance coefficients of the second stage are significantly higher than those of the first stage. This study provides an effective method for calculating the porous medium resistance coefficients for each stage of two-stage brush seals and for predicting their leakage characteristics.