Two-Way Brush Seals Catch a Wave

This article explores a set of inner and outer brush seals capable of bidirectionally restricting flows in a wave rotor, which has been successfully fabricated and tested. Advantages cited for the wave rotor include enhanced efficiency, rotor material temperatures lower than the peak gas temperatures, lower speed rotation with reduced stress, simple robust construction, and rapid transient response. A cross-sectional view of the rotor shows the cavities and placement of the brush seals. No definitive tests were undertaken during the break in stage or during the testing; thus, one can only conclude that the bristles wore significantly, and the rotor coating showed little evidence of tracking other than being highly polished with some spottiness. Some powder debris was found in the exhaust port. The principles of bidirectional brush design can be applied to all brush configurations, providing bidirectional capability, controlled seal stiffness/damping, bristle spread, flutter, protection from foreign object damage, and a double labyrinth-orifice at essentially the same cost as a conventional brush seal construction.