Testability modeling of aeroengine and analysis optimization method based on improved correlation matrix

Abstract

This paper aims to optimize the testability analysis method of aero-engines by presenting a testability modeling and an improved correlation matrix method. Because of strong coupling in aero-engines, the traditional testabilitsy modeling method based on graph theory is difficult to accurately express the relationship between faults and test points. Simulation technology can simulate actual work process of system. So this paper launches the research based on simulation model. Firstly, the gas path model is established according to the thermodynamic principle of aero-engines and accuracy of the model is verified. Secondly, common faults of gas path are selected. Affected parameters are obtained after injecting faults into the model, so as to obtain the relationship between faults and test points, that is, the correlation matrix. Then, after going through masses of simulations, it is found that the relationship between faults and test points can be divided into three categories: positive correlation, negative correlation and no correlation. The correlation matrix can be improved by diversifying its elements. During simulation, accuracy of the sensors are not considered. The correlation matrix is optimized with the accuracy of sensors in the gas path as a constraint, so that it is more in line with engineering practice. Finally, four testability characteristics and two testability metrics are defined, and the correlation matrix before and after improvement are analyzed and compared. It is found that the improved correlation matrix can isolate more faults on the premise of reducing test points, which proves the effectiveness of the proposed method.