RESEARCH METHOD OF THE AIRCRAFT ENGINE HOUSING VIBRATION WHEN THE FAN BLADE ABRUPTION

Abstract

Following the Certification Specifications, at the design stage, the structural strength of the aircraft is calculated when the blades abruption and the engine bearing is destroyed, which cause large vibrations. At the finalization stage, these calculations should be confirmed by tests. The most effective way of dynamic test operation now is a numerical simulation because it makes it possible to study the influence of a large number of different factors, to analyze structural vibrations in those modes that are impossible or dangerous to reproduce in full-scale tests, significantly saving time and material resources. Studies of transient vibrational processes for a simplified calculation model of linear deformation of bearing assembly were performed. The most dangerous case of damage to the fan blade abruption is considered. The engine is attached to the pylon at five points. Two attachment points to the front traverse and two attachment points to the rear traverse are hinges with axes parallel to the axis of the engine. The fifth point is a hinge with an axis perpendicular to the vertical plane. At this point, the engine is attached to the pull rod. In the first approximation, we assume that the body is solid, and its center of mass is located on the axis of rotation of the rotor. We consider traverses as elastic beams working in bending, and the rod for lifting the thrust as an elastic rod working in tension. We simulate the rotor with a solid body on bearings, since the deformations of the rotor parts are small in comparison with the deformations of the bearings and the lowest natural frequency of the oscillations of the rotor as an elastic body is an order of magnitude higher than the frequencies of the rotors on the bearings. The frequency response of the rotor, the dependence on the time of movement of the support sections, and the orbits of the centers of the support sections of the rotor relative to the stator are obtained. The frequency response of the engine with the rotor, the dependence on the time of the generalized stator coordinates is constructed. An analysis of the applicability of the developed model and calculation method for different cases of damage to the rotor and its bearings is carried out. The importance and prospects of continuing research with nonlinear calculation models are shown.

Keywords

• двигатель
• ротор
• повреждение
• дисбаланс
• вибрация
• численное моделирование