While the efficiency of a brush seal is measured by its leakage rate, the overall performance of the seal is mostly affected by wear rate and durability. Seal stiffness and hysteresis behavior play important roles in determining the leakage performance and rotor stability due to the fact that they directly affect wear rates and pressure load capacity of the seal. The complicated nature of the bristle, rotor and backing plate interactions at typical operating conditions makes it difficult to determine the stiffness and durability of brush seals. In this study, test and computer aided engineering (CAE) methodologies have been developed to simulate brush seal stiffness and stress levels at unpressurized conditions. Unpressurized stiffness tests have been conducted by using two different test rigs, one of which uses a simple metallic pad and the other one uses a full-sized rotor for seal interference measurements. Test results for the two different rigs have been compared and the drawbacks of the simple stiffness test rig have been detailed in this study. CAE analyses at unpressurized conditions have been conducted by using 3D finite element (FE) models, and analyses have been correlated with the stiffness tests. The influence of rotor rotation has also been analyzed at unpressurized seal conditions. Transient simulation results also demonstrated good agreement with the dynamic stiffness tests of the brush seals.

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