Journal of Theoretical
and Applied Mechanics

50, 4, pp. 913-921, Warsaw 2012

Phase mapping in the diagnostic of a turbojet engine

Mirosław Kowalski
This paper describes possibilities of using the phase portrait for the diagnosis of the turbojet engine AŁ-21F3 type. Attention is paid to description of the theoretical basis of application of this method to identify the engine fuel system. The identification of the engine fuel system was conducted for each operating adjusting point according to the mono-selection 3r plan with variable data sampling period with a frequency equal to a constant submultiple of the engine rotation frequency. It is explained how the settings of the operational control of the AŁ-23F3 engine fuel system influence the shape of the phase characteristics of engine rotation speed. Additionally, the location of the phase portrait distinctive points is determined. Moreover, there are shown examples of phase portraits for selected ranges of engine operation. It is shown, as an example of using the phase mapping, the ability to monitor parameters of the automatic engine start up using the adjusting machine screw of the altitude corrector of the start-up automaton and changes of the diameter of the start-up automaton nozzle. It is also shown that the qualitative analysis of the adjustment of specific ranges of engine operation is sufficient to determine the influence of the individual adjusting points for those operating ranges.
Keywords: aircraft engine diagnostics; phase mapping of engine parameters