Study on dynamic characteristics of the helicopter main transmission system

ObjectiveTo identify the main excitation frequencies that cause the vibration of the helicopter main transmission system and reveal the influence of system speed, rotor torque, and rotor lift on the dynamic characteristics of the helicopter main transmission system.MethodsThe dynamic characteristics of the helicopter main transmission system were studied using test methods, including rated condition tests, different rotor torque tests, different rotor lift tests, and different speeds.ResultsThe results show that the helicopter main transmission system has the highest vibration in the high-speed stage, followed by the vibration in the planetary stage, smaller vibration in the intermediate stage, and the smallest vibration in the low-speed stage. The vibration excitation of the helicopter main transmission system can be transmitted both in the direction of the drive chain power and in the direction of the reverse power flow. The meshing excitation of high-speed stage, low-speed stage, and planetary stage is the main excitation that causes the corresponding stage vibration of the system, while the main excitation that causes the intermediate stage vibration of the system is the meshing frequency of the planetary stage and high-speed stage. The vibration of the helicopter main transmission system gradually increases with the increase of rotor torque when the rotor torque is greater than 3 000 N·m, while the influence of rotor lift on the system vibration is relatively small.