EVALUATION OF BRUSH SEAL PERFORMANCE FOR OIL SEALING APPLICATIONS

Oil sealing at high speeds is one of the major problems engineers should address in turbomachinery design. High temperatures faced in oil sumps in aircraft engines, and large seal sizes typical in land based turbine applications further complicate the problem. Labyrinth seals can overcome problems faced with carbon seals in high temperature and large size applications. On the other hand, use of labyrinth seals may result in high leakage rates leading to increased oil consumption, unintended oil contamination in some flow cavities, early oil degradation or even fires in some cases. Successful engine secondary flow path applications of brush seals lead to questions of their applicability for oil sealing. Because brush seals are contact seals, oil temperature rise and coking become major issues in addition to leakage performance. This paper presents an investigative study of brush seal leakage and coking performance using common lube oil. Both metallic and non-metallic prototypes have been tested under static and dynamic conditions. It has been concluded that properly designed brush seals can achieve lower leakage rates than labyrinth seals without causing coking problems.