Session: 27-05 Non-Linear Rotordynamics

Paper Number: 126479

126479 - The Safety Design Method for the Rotor System With Fan Blade Off 

Under extreme loads, high bypass-ratio turbofan engines are vulnerable to fan blade off (FBO) failure, which poses a significant threat to flight safety. To address this issue, current aero-engines frequently employ the fusing or semi-fusing failure design for the rotor's front support structure. This allows for modifications to the load transfer path and distribution, hence enhancing the structural safety. This paper establishes a safety optimization design strategy for the FBO rotor system. The optimization variables are the time-varying parameters related to the rotor speed and support stiffness, and the optimization objectives are the amplitude and supporting force of the key position of the rotor.

The numerical sampling test design method is used to analyze the influence of support stiffness variation duration, support stiffness variation amplitude, and speed deceleration duration on the dynamic response of rotor system. Accordingly, the number of objective functions of the optimization problem is reduced from 27 to 4, which are the fan disk's peak critical amplitude, the 2# pivot's peak critical amplitude, the fan disk's steady-state amplitude, and the 1# pivot's peak critical reaction force. The dynamic optimization model of FBO rotor system is established using the NSGA-II genetic algorithm, and the Pareto solution set of the optimization problem is obtained based on the finite element model. The response surface surrogate model of the optimization issue is constructed utilizing the radial basis function (RBF) model in order to increase the solution efficiency, and the outcomes are compared with those of the finite element model. The optimal solution is finally selected from the Pareto solution set using the suitable screening approach, so as to complete the dynamic optimization design of the FBO rotor system.

The results show that the support stiffness variation duration primarily affects the peak value of impact amplitude and impact reaction force of the low-pressure rotor. In contrast, the influence on the peak value of critical amplitude and steady-state amplitude is minimal. The support stiffness variation amplitude greatly affects the critical amplitude, critical reaction force, and steady-state amplitude of the 1# pivot. The speed reduction duration has a significant influence on the peak value of critical amplitude, a negligible influence on the peak value of impact amplitude and impact reaction force, and no influence on the steady-state amplitude and steady-state response force. The optimization method based on the response surface surrogate model can reduce computational costs by more than 4 orders of magnitude when compared to the full finite element model. The Pareto solution set of FBO rotor system can be divided into two regions, corresponding to the structural design ideas of partial fusing design and complete fusing design respectively. In addition to the steady-state amplitude of the fan disk, the other three objective functions have achieved good optimization results, and the value of each objective function has been reduced by more than 45 percent. In general, the optimal solution of the corresponding area of complete fusing design is better than that of partial fusing design.

Presenting Author: Zhenyao Zhao Beihang University

Presenting Author Biography: Zhenyao Zhao, Ph.D student at Beihang University, mainly engaged in research on rotor dynamics and vibration optimization design.

Authors:

Zhenyao Zhao Beihang University
Dayi Zhang Beihang University
Cheng Yang Byd Auto Industry Company Limited
Qicheng Zhang Beihang University