Study On The Impact Analysis Of Aero-engine Limit Protection Under Sensor Failure

"For development of civil aviation,airworthness first".In order to develp Chinese large aircraft,the airworthness administration put forward a series of requirements for safety of the engine control system.In the control system,there is an indispensible hardware subsystem that is sensor,which can achieve the function of closed-loop control by sensing and passing the information.However,sensor failures will be happened in the aero-engine because its extremely operation environment.The key variables should be limited(such as fan speed or turbine temperature),which maintain their limit.At present,the reserach of limit protection usually is worked under normal sensor at home and abroad.In the paper,a series of researches are carried out for the engine limit protection from the perspective of sensor failures.The main contents are as follow:First of all,the paper analyzed the impact of aero-engine speed control loop under sensor failures and steady state without limit protection.All kinds of faults such as bias fault,drift fault,impulse fault,open fault,short fault,and periodic interference fault were found within in sensor failure,which injected into the speed control system by the current form of signal.In order to study the impact of sensor failures for the fan speed control system without limit protection,and signal changing trends were observed from fan speed response,fuel flow output,deviation signal,and sensor output signal.The simulation results show that open fault that lends to the largest influence on the control system,and impulse fault that lends to the smallest influence on the control system.There is an influence degree order form small to large,which speed control system under speed sensor failures: impulse fault,bias fault,short fault,drift fault,periodic interference fault,open fault.Secondly,study on the impact of speed limit protection control under speed sensor failures and based on set-point control system.Study on output response of speed control system seriously deviates from set-point.Under speed sensor failures,technology of limit was proposed to design and limit parameter was set,which added to system,and compared with the system of limit protection control.The simulation results show the system that have own limit protection,which possesses certain ability to tolerate fault and significantly decrease impact of failure.Thirdly,study on impact of turbine temperature control system based on transient under temperature sensor failures.In view of large temperature overshoot when system always shows instability on the transient.Limit protection was applied to limit turbine temperature and parameter was set to study the influence sensor failures.The simulation results show that the limit protection significantly decreases overshoot and appears two switch times,and achieves smooth control.Meanwhile,switch time of limit protection has delay or leading,which are related to failure degree of sensor and limit parameters.The paper study on impact of aero-engine limit protection from sensor failures,especially different sensor failures and set limit,the phenomenon of switch time delay and leading are found on the control system,which develop research of aero-engine limit protection,and also provide some technical support for airworthiness certification.Therefore,some innovations are showed in the paper.