Abstract
A turbofan nonlinear dynamic model is described in the paper. It has been developed for the computation of loads in the engine frame after fan blade-out (FBO) event. The model includes reduced dynamic finite element models of rotors and casings and also nonlinear elements for simulation of “rotor-casing” contact interactions. Thorough attention has been paid to mounts modeling with possible mechanisms taken into account. The engine dynamic behavior during its rotors deceleration to the autorotation mode after the FBO event has been simulated for the following two forward mount arrangement variants: fastening to the inner part of the intermediate casing; fastening to the outer part of the intermediate casing. The effect of load reduction device (LRD) – special elements which are introduced to fan supports, destroyed under certain force and don’t transfer improper loads to the engine casing system after the FBO event, has been studied. The analysis of maximum loads on engine mounts has been performed for the two listed design variants for both cases: with and without an LRD in fan supports.
Highlights
Fan blade out event is the load case which determines limit loads on engine frame elements
As it can be seen from these tables, if load reduction device (LRD) is implemented in fan supports, maximum loads reach their minimum in the case of first mount arrangement variant
This paper is dedicated to the turbofan nonlinear dynamic model
Summary
Fan blade out event is the load case which determines limit loads on engine frame elements. The centrifugal force after FBO event may reach the values about 1.0∙106 N at maximum turbofan rotors velocities This value is significantly more than loads caused by regular unbalances. The maximum loads in the turbofan frame elements after FBO event may occur either at the moment of FBO, when the unbalance force is applied, or at passing resonance during rotor slowing down. The number of researches has been dedicated designing dynamic model of the rotor or the whole engine in order to calculate engine frame loads after FBO event [3,4,5,6,7,8,9,10]. This current paper describes the MSC Nastran dynamic engine model for frame loads computation after FBO event. The two variants of engine mount arrangements are considered and corresponding dynamic loads after FBO event are compared
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