Field balancing technology for low pressure rotors of high bypass ratio turbofan engines

For high bypass ratio turbofan engines, a field balancing method for low pressure rotors was established based on least-square influence coefficient, and a testing system for dynamic balancing was developed. After a model rotor experiment rig was built up, relevant calculation of dynamic characteristics and balancing experiments were conducted. And the correctness, validity and reliability of the field balancing technology were verified in a bench experiment of actual engine. Results indicated that using the method of tracking high pulse and transforming square wave according to fixed proportion can identify the high-tooth signal, and integral period interception, interpolation processing and multiple times averaging of vibration signals can ensure the accuracy and stability of speed and phase measurement. The No. 1 support was more sensitive to the fan unbalance, and the No. 5 support was more sensitive to the turbine unbalance, while the No. 2 support was sensitive to both unbalances, and the sensitivity to the fan unbalance was greater. Under the premise of ensuring the balancing effectiveness, when compared with the three-circle balancing method, the field balancing technology for low pressure rotors can also facilitate the operational convenience, decrease the number of startups and shutdowns, and achieve less time consumption with a bright prospect in engineering application.