Functional Hazard Analysis Of Electronic Control System Of Civil Turbofan Engine

During the operation of the civil turbofan engine electronic control system,due to the influence of working conditions and environmental conditions,malfunctions may occur and affect the normal operation of the system.The airworthiness clause CCAR33.28 stipulates the safety of aero-engine control systems.Among all the safety analysis methods of electronic control systems,functional hazard analysis is the first step.In order to further study Failure Mode and Effect Analysis of the engine electronic control system and provide analysis supplement for the confirmation of the impact level in the functional hazard analysis,this paper provides a model-based electronic control system failure analysis method.The main research content of this article is divided into the following three parts:First,based on a component-level model of a large bypass turbofan engine in our laboratory,a dynamic model is established using the flow balance equations and rotor dynamics equations,and the Newton-Raphson and Euler methods are used to solve the dynamic model,which is also verified.Then,based on the dynamic response data obtained from the dynamic model simulation,a linear deviation method is used to calculate the linear state space model of the engine with small deviations.Second,the failure model of the electronic control system is explored.First,an electronic control system model needs to be built,then a corresponding malfunction model is established according to the malfunction state,and the malfunction model is injected at the end.The paper takes the VSV control function as an example to establish a malfunction model,then adds the failure model to the component-level model,obtain a linear model under malfunction according to the dynamic data in the malfunction state.Replace the engine linear model in the electronic control system to implement the malfunction model injection.Third,quantitatively analyze the impact of the malfunction of the electronic control system and determine its failure impact level.After the injection of the malfunction model is completed,simulation analysis is performed at different flight stages.Then reference to airworthiness clauses,the failure impact level is confirmed by studying the deviation range and change trend of various performance parameters of the engine.Taking the VSV control malfunction as an example,the paper analyzes and determines the failure effect level caused by the malfunction in detail,and proves that the quantitative analysis method can be used as an engine in addition to the traditional method for determining the failure effect level based on expert experience and subjective analysis.The supplementary analysis of the functional failure impact of the electronic control system completes the conclusion of the functional hazard analysis.