Model-based reasoning for fault diagnosis of twin-spool turbofans

Abstract

A simplified rule-based expert system can be of great use to maintenance engineers involved in on-line health monitoring of aero-engines. The development of a rule base has been done on the following lines:

A design and off-design mathematical model of the turbofan has been developed.

Healthy and fault-implanted engines have been run at various off-design conditions to see the effect of faults on certain aero-thermodynamic performance parameters, with appropriate selection of independent parameter(s).

From these calculated values, fault matrices have been developed for sea-level static conditions taking the net thrust as an independent parameter.

From these fault matrices, rules have been developed which form the knowledge core of the expert shell.

These rules have been developed for Garrett TFE 731-2, a moderate bypass and overall pressure ratio, generic twin-spool turbofan and so the package (off-design code plus expert system) can serve as a pedagogical tool for training of engineers in the aero-engine industry and academic institutions.

Keywords

twin-spool turbofans fault diagnosis model-based reasoning expert systems fault matrices

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