Current seal designs and future requirements for turbine engine seals and bearings

Turbine engine mainshaft seals are a significant factor in the overall engine performance. Each engine application presents a different set of requirements often dictating solutions that employ one or more of the basic seal types; ring seal, face seal, or labyrinth seal. The aircraft turbine engines of the 1980* s with co-rotational rotors will require seals that can operate at pressure differentials within the 345 N/cm (500 psi) to 413 N/cm (600 psi) range, gas temperatures within the 922°K (1200°F) to 1032°K (1400°F) range and surface velocities within the 152 m/sec (500 fps) to 183 m/sec (600 fps) range. Currently developed seal systems demonstrate limited capability for meeting advanced requirements without imposing severe performance and system penalties. Mainshaft bearings for these advanced engine applications will require operation in the 2.5 to 3.0 X 10 DN level range. Of the two basic bearing types employed, ball thrust and cylindrical roller, the latter presents the most challenge. Additional bearing and mainshaft seal development is required to meet the requirements of tomorrow's aircraft engines.