Measurements of leakage, structural stiffness and energy dissipation parameters in a shoed brush seal

The shoed brush seal is a modification of a standard brush seal that has a number of arcuate pads at the free ends of the bristles. A major benefit of this novel design is that it allows reverse shaft rotation. It also eliminates bristle wear as the pads lift off due to the generation of a hydrodynamic film during rotor spinning. This type of seal, able to work at both low and high temperatures, not only restricts secondary leakage but also acts as an effective vibration damper. The dynamic operation of the shoed-brush seals, along with the validation of reliable predictive tools, relies on the correct estimation of the seal structural stiffness and energy dissipation features. This article describes tests to measure these parameters and compare the results with predictions.