Rotor system (RS) is the main unit in the highly energy-intensive turbomachines, such as the gas turbine engines (GTE) operating for the aviation and ground purposes. Its stable operation in the design (standard) modes determines the machine reliability and durability as a whole. However, in a number of cases related to the mechanical system safety, the GTE RS operation analysis is required in the off-design (emergency) modes. One of them is the RS dynamic behavior in the case of the GTE fan working blade out. The paper presents computational and experimental approach to mathematical simulation of the GTE axial RS dynamic behavior when the fan stage rotor blade breaks. The low-pressure cascade rotor operating under conditions of a two-rotor system designed for a real dual-circuit GTE is considered as the study object. The RS build-up structure mathematical simulation is carried out on the basis of the finite element method (FEM) and solving the contact problem of the elasticity theory. The following dynamic modes sequence of the GTE operation is considered: increase in the rotor speed from zero to maximum, maximum mode, blade out, fuel cut-off, and the rotor with a blade-out passes into the autorotation mode. The blade-out is simulated using results of the GTE RS full-scale testing in the form of a diagram of alteration in the center of mass radius (imbalance) of the fan during the blade-out process. Numerical experiment presented in the work shows that, along with a significant increase in the oscillation amplitude at the blade-out moment, an additional peak (response) in oscillation amplitudes occurs during transition to the autorotation mode, and it is associated with the rotor operation in the flexible shaft mode. In general, the RS mathematical model shows fairly stable behavior in the presented abnormal mode, which is also confirmed by results of the full-scale testing.

EDN VDBMUX