To improve the intershaft seal performance of the dual-rotor turbofan engine and extend the life of the intershaft seal, a compliant cylindrical aerodynamic intershaft seal structure is proposed, which avoids the problem of leakage increase after tooth wear of intershaft labyrinth seal. According to the proposed seal structure, the force condition of the floating seal ring is analyzed, and an aeroelastic coupling method for the floating seal ring eccentricity is presented. And the leakage characteristics, with different seal structures and operating conditions are calculated and compared when the two rotors are under homodromy/counter-rotating condition. The results show that, for the dual-rotor cylindrical hydrodynamic gas film seal, the hydrodynamic effect under homodromy condition is enhanced greatly while the hydrodynamic effect is significantly weakened under counter-rotating condition; the rotational direction of rotors, seal width, rotor circular precession eccentricity, rotational speed and rotor radius all have pronounced influence on the seal performance. For the application of hydrodynamic form of compliant cylindrical intershaft seal, the seal performance under homodromy condition is better than that under counter-rotating condition.
Keywords: Intershaft seal; aeroelastic coupling; compliant cylindrical gas film seal; dual-rotor homodromy/counter-rotating.