Low-Leakage Brush Seals for Rocket Turbopumps

It has been proven, for gas turbines, that brush seals exhibit substantially lower leakage in close clearance areas than conventional labyrinth seals. Direct efficiency gains from reducing seal leakage losses in turbopumps with brush seals potentially amounts to several percent of the total pump power consumption. As such, the case for transitioning brush seals to rocket turbopumps is compelling, though some technology development is required to overcome technical challenges. Besides direct efficiency improvements, decreased leakage flows, in conjunction with proper seal design, can enhance the operational range of the pump. Advanced brush seal configurations designed to optimize rotordynamic behavior can increase operational life and reduce maintenance costs and downtime. The development is proposed of rocket turbopump brush seals that will significantly decrease stage leakage losses while simultaneously optimizing tribological and rotordynamic behavior. In Phase I, several advanced brush seal concepts will be investigated analytically in a cryogenic environment, and experimentally in water. In Phase II, promising concepts will be fabricated and rig tested. The most promising concept will then be tested in a turbopump test stand, with success helping to meet IHPRPT goals for increased payload capacity, longer service liefe, and advanced rocket engine capabilities (such as wider operating range).