涡扇发动机低压轴断裂故障在线检测方法

针对低压轴断裂易引起涡轮飞转的问题,需在运营环境中进行涡扇发动机低压轴断裂的机载在线检测。采用机载测量的高压物理转速和低压物理转速等参数,建立了基于物理转速变化率和转差关系的低压轴断裂故障在线检测方法。通过发动机工况仿真识别了能够准确区分正常加减速过程、喘振过程和断轴过程的物理参数,设置了检测判定逻辑和判定阈值。结果表明:在断轴后的0.1 s内,低压转速变化率出现瞬间最小值;在0.2 s内,高压转速变化率变为正值。该方法检测响应时间为0~0.5 s,可以实时检测出低压轴断裂故障,有利于控制系统及时采取停车等处理措施以防止核心机被损坏,不会由于发动机正常停车、加减速、喘振和高压轴断裂而导致虚警,检测可靠性高,具有较高的工程实用性。

On-line Detection Method of Low-pressure Shaft Fracture Fault in Turbofan Engine

In order to solve the problem of turbine overspeed caused by low-pressure shaft fracture,it was necessary to carry out onboard on-line detection of low-pressure shaft fracture of turbofan engine in the operational environment.Using the on-board measured parameters such as high-pressure physical rotor speed and low-pressure physical rotor speed,an on-line detection method of low-pressure shaft fracture fault was established based on the relationship between change rate of physical speed and the slip.Through the engine working condition simulation,the physical parameters which could accurately distinguish the normal acceleration and deceleration process,surge process and shaft fracture process were identified.The detection decision logic and decision threshold were set.The results show that the change rate of low-pressure rotor speed has an instantaneous minimum within 0.1 s after shaft fracture,and the change rate of highpressure rotor speed becomes positive within 0.2 s.The detection response time of this method is 0~0.5 s,which can detect the fracture fault of low-pressure shaft in real time.It is conducive to the control system to take timely shutdown and other treatment measures to prevent the core engine from being damaged,and will not cause false alarm due to normal engine shutdown,acceleration and deceleration,surge and high-pressure shaft fracture.This method has high detection reliability and high engineering practicability.