Experimental and numerical study on the leakage characteristics of brush seals at the early stage of operating

Experiment was carried out to investigate the leakage characteristics for brush seals at the early stage of operating. Two brush seals were tested for 27 and 50 hours, respectively. The experimental results were then analyzed with the porous medium model. The experiment shows that during the early stage the mass flow rate is linear with the pressure drop across the seal. The leakage level of new brush seals gradually decreases and finally keeps on a stable level as the time accumulates. The numerical study indicates that the bristle arrangement is loose at the beginning. Then, it becomes denser and denser and finally reaches a stable level which is close to the staggered arrangement. This process changes the porosity of bristle pack, which leads to the change of the flow resistance. This explains why the leakage level of brush seals changes.