Rod fastened rotor is widely used in gas turbine, aero engine, and other occasions. The bending stiffness of the contact interface directly affects the stable operation of the rotor. Dynamic model of the rod fastened rotor-bearing system has been established considering nonuniform stiffness of interface. The motion equation of this system has been deduced from Lagrange's equations. The linear dynamic characteristics of this rotor has been investigated, such as Campbell diagram, critical speed, and formation, and the nonlinear characteristics of this system, such as chaos and bifurcation, has been investigated too. The result shows that "bistable state" characteristic appeared on the rod fastened rotor system; that is, there are two critical speeds for each order, and they are all positive precession critical speed, and the amplitude response to the lower critical speed is much larger than that its counterparts to the higher critical speed. In terms of nonlinear characteristics, the rod fastened bearing system has experienced periodic 1 motion, multiple periodic motion, quasi-periodic motion, periodic 1 motion, and chaotic motion successively.

Elastic rings are extensively utilized in aero-engine rotor systems owing to their compact size and ease of assembly, where they play a critical role in vibration suppression during engine operation. The dynamic behavior of elastic rings is governed by their structural parameters, with stiffness being a pivotal factor influencing the rotor system’s performance. This study employs finite element methods to investigate the effects of elastic ring structural parameters, particularly the geometric features of bosses and internal/external assembly clearances, on stiffness nonlinearity, with a focus on its mechanisms and contributing factors. The results reveal that stiffness nonlinearity emerges when the whirling radius exceeds a critical threshold. Specifically, increasing the boss width, reducing the boss height, or augmenting the number of bosses all attenuate stiffness nonlinearity under identical whirling radii. Furthermore, external clearances exhibit a stronger capability to suppress stiffness nonlinearity compared to internal clearances. Engineering insights suggest that maintaining a small clearance fit during assembly effectively mitigates stiffness nonlinearity, thereby enhancing the rotor’s dynamic performance. This study elucidates the stiffness nonlinearity behavior of elastic rings in practical applications and provides actionable guidance for their design and operational optimization in rotor systems.

Film cooling is extensively utilized to protect the high-pressure turbine blade in advanced aero engines from high-temperature gases. In many of the current studies and design optimizations, artificial intelligence is deployed with deep learning, with datasets often generated based on Computational Fluid Dynamics (CFD) simulations of the cooling effectiveness of film cooling holes. In the current study, first, a variety of aerodynamic and geometric parameters are studied, including the blowing ratio, injection angle, laidback angle, lateral angle, etc. The various design parameters and flow conditions of fan-shaped holes are interrelated, and comprehensive considerations must be carefully carried out. Second, the numerical results are used as input datasets for several neural network models. Different neural network architectures are employed to estimate the film cooling effectiveness. The outcomes demonstrate that a well-designed neural network model with moderate layers can accurately predict film cooling within a tiny fraction of CFD computing time, even with a small dataset. Finally, the sparrow search algorithm is adopted to optimize the parameters of the cooling hole inside the design space. This demonstrates that the neural network approach is a powerful tool with great potential for numerical design and optimization of a massive number of film cooling holes on an entire blade.

A rod fastened rotor (RFR), which contains serial disks, rods (or a rod), and a torque tube, is the main form of heavy duty gas turbines and light duty aero engines. The roughness of the interface is the main parameter affecting the bending stiffness of RFR, and the jumpiness of the disks is the intuitive representation of the unbalance of the rotor. In this paper, a multi-optimization algorithm, NSGA-Ⅱ, was used to improve the vibration behavior of the RFR-bearing system. First, the quantitative relation between the bending stiffness of the rotor and the roughness of the interface was set up by combining the Persson contact theory and the Greenwood–Williamson model, and the nondimensional bending stiffness (NS) was proposed as the optimization objective of roughness. Then, the optimization objective of the jumpiness of the disk, (A + B), was rendered based on the minimum unbalance force. Finally, the multi-optimization on the roughness and jumpiness of the RFR was carried out, and the vibration behavior was improved greatly. In addition, this multi-optimization method was applied to a practical RFR, and the experimental results showed that the vibration amplitude was reduced by about 82%. The work in this paper can provide the guidance for vibration reduction of the rotor system.