Coupling Dynamic Characteristics Analysis of a Dual-Rotor Aeroengine

Aiming at the typical dual aeroengine with inter-shaft bearing, the dual-rotor dynamic analysis model was established. The dynamic characteristics induced by the high pressure rotor excitation of the co-rotating, counter-rotating system and the inter-shaft bearing were thoroughly analyzed. Results show that the critical speed of the co-rotating system was much higher than the counter-rotating system, resulting from the gyroscopic moment. Consequently, the rotor strain energy was lower and the rotor unbalance would generate lower dynamic response at critical speed. More importantly, the critical speed of high pressure rotor and low pressure rotor coupling mode (HLCM) would lead to the dramatic increase of coupling vibration. To be specific, the shaft axis locus demonstrated an obvious petal-like shape and the reaction force of the inter-shaft bearing rose significantly. The findings highlight the importance of maintaining sufficient margin between the critical speed of HLCM and the engine operating speed during the rotor dynamic characteristics design.