22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-5.3.2

AIRCRAFT ENGINE RESPONSE DUE TO FAN UNBALANCE AND TO THE PRESENCE OF "CONSUMED" GAPS IN THE ENGINE DURING THE PHASE OF WINDMILLING

B. Bernay
AEROSPATIALE MATRA AIRBUS, France

Keywords: aircraft engine, fan unbalance, windmilling

When fan blade off and gaps in a Turbomachine occur, non-linear loads take place. After a transient phase the main rotor reaches a “windmilling” motion, inside some frequencies range. Jump and hysteresis phenomena are observed in this range. The paper presents two models for the dynamical simulation of the windmilling motion. First, a simplified model is used for which analytic solutions are obtained. The results are compared to the numerical integration of a finite element model of the aircraft. Based on this analysis, an harmonic method has been developed to compute the jump frequency; a sensitivity study of the different parameters related to the jump phenomenon is performed.

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