Brush seal performance measurement system

Brush seals are rapidly replacing conventional labyrinth seals in turbomachinery applications. Upon pressure application, seal stiffness increases drastically due to frictional bristle interlocking. Operating stiffness is critical to determine seal wear life. Typically, seal stiffness is measured by pressing a curved shoe to brush bore. The static-unpressurized measurement is extrapolated to pressurized and high speed operating conditions. This work presents a seal stiffness measurement system that is capable of measuring brush seal stiffness under engine operating pressure and speed condition which is not available in open literature. Stiffness measurement system design, testing methodology and calibration procedure are discussed.