ROTORDYNAMIC OPTIMIZATION STRATEGY OF THREE SPOOL ARRANGEMENT FOR VARIABLE CYCLE ENGINE

Variable cycle engines provide better fuel economy, additional thrust, and more durability than the state of art, because of solving the inherent contradiction between subsonic and supersonic flight through different thermal cycles, which is a promising solution for the future aero-engine. Aiming at the new multi bypass intake variable cycle configuration with interstage combustor, in order to improve the rotordynamic problems caused by the variable cycle characteristics, this paper proposes a rotordynamic optimization strategy for a matching three spool arrangement. The rotational directions and support stiffness are optimized to avoid the coupling vibration of model between the two rotors of core engine with innershaft bearing in the wide and variable working speed range. And the configuration of turbine journal is optimized to improve the critical speed margin and control the bearing dynamic load of flexible rotor with large aspect ratio. Results of the simulation show that, the optimized three spool arrangement displays more sufficient critical speed margin, weaker coupling vibration and lower bearing dynamic load than the former design, which meets the requirements of rotordynamic design and has a promising engineering application prospect.