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Maneuvering flight can generate the asymmetry of the stiffness or damping to an engine rotor system, as so to influent the whirl direction and characteristics of rotor system. In this article, the identification method for orbit direction is provided for a rotor system under maneuvering flight condition. By a simulation example, the variable movement shapes about rotor under maneuvering flight are illustrated through cases as the mixed and the pending whirls. The results show that the original low-order critical speed in the backward or forward whirl mode changes to the mixed whirl while considering the impact of maneuvering flight, where some backward and forward critical speeds in the same order are almost overlapped as one critical speed which in the mixed whirl mode. Maneuvering flight results in dynamic eccentricity of the rotor shaft, and the orbits of nodes in the mixed whirl are a series of ellipses with variable inclination angles. The case with pending whirl direction is finally determined as a mixed whirl by the orbit direction graph. The whirl directions of orbits on bearings or the contact angle of bearings maybe different under maneuvering flight can be explained from the rotor dynamical view.

In this paper, the rotor system with nonlinear bearing force and base excitation load was modeled based on finite element method, and its response characteristic under the excitation of base load was studied. The results show that the response of the rotor is the superposition of the basic impulse response and the unbalanced response. The pulse excitation energy can be dispersed while the rotation speed and pulse frequency are close to each other. When the phase difference of unbalanced excitation is 180°, the response amplitude of rotor bearing system was the smallest. The correctness of the rotor bearing system model was verified by experiments.

In order to study the dynamics similarity of original model similar to normal model, the similarity criteria and the similarity ratio of the normal and original models for the rotor system were derived by the dimension analysis method. ANSYS was used to numerically calculate the critical speeds, modal shapes and harmonic response of the original and normal models of rotor system. The analysis results show that, for the rotor system, the dynamic characteristics of the normal and original models satisfy the requirement of the similarity criteria perfectly. The dynamic characteristics of the original model can be predicted accurately by the corresponding normal model.

Variation of film pressure was studied by short bearing hypothesis and differential method for grooving on film inner-face. The results were compared with those of FLUENT analysis. Then, effects of the position of groove were studied on film pressure and damping through differential method. The results shown that short bearing hypothesis cannot conform to the actual situation considering grooving. The effect of grooving on the pressure distribution of film was researched by differential method, and the results are consistent with the FLUENT simulation analysis. Side grooving has less effect on film pressure and damping, so it is recommended when the design and assembly conditions are allowed.

With the development of science and technology, traditional design methods can no longer meet the needs of modern design and production development. Parametric and optimal design has become one of the most popular application technologies in CAD. Parametric and optimal design was studied based on VB.net language for secondary development of AutoCAD and MATLAB language for secondary development of ANSYS Apdl for disc of aero-engine. The structural parameterization technology was used to realize the rapid forming, and genetic algorithm retains elite was used to optimal design. The optimal design was carried out by using the developed software in this paper, and the optimal results shown that the disc weight was reduced by 34.48 %, the reduction effect of weight was obvious.

Experimental modal analysis of a turbine disk was conducted with the hammering method. The first five modals were obtained, matches well with calculation results of ANSYS, and proves the effectiveness of the experiment, provides a reference for further improvement of a certain engine.

In order to study the dynamic characteristics of a rotor system incorporated with roller bearings, a detailed finite element model of the rotor system was established. Both the roller bearings and pedestals were considered. Then investigations on dynamic characteristics of the rotor system were conducted, in which critical speeds and unbalance response of the rotor system were obtained and analyzed. Following conclusions can be reached from the numerical results: 1) the second and third critical speeds of the rotor system are 25260 rpm and 113400 rpm, both of which are outside of the operating speed range 31800 rpm-55320 rpm. 2) Within the operating speed range 31800 rpm-55320 rpm, unbalance response of both the centrifugal impeller and the turbine disk are smaller than the corresponding clearances. However, with increasing rotational speed, amplitude of the unbalance response for the centrifugal impeller increases while that of the turbine disk decreases.

To reduce computation effort, model reduction technique has been widely used in rotor dynamics. In this paper, different model reduction methods, including Guyan reduction, dynamic reduction, improved reduction system (IRS), System equivalent expansion reduction process (SEREP) and component modal synthesis method (CMS), were introduced and compared. All methods were applied to a single rotor system to obtain the critical speeds. By the eigenfrequencies comparison and the MAC comparison, it was found that CMS was the most convenient reduction method for rotor dynamics.

Sealing disk-baffle integrated structure has been widely applied in modern advanced aero-engines. In this paper, the features of typical sealing disk-baffle integrated structure were analyzed in order to explore the feasible direction of the structure design and optimization. The finite element models were analyzed for the CFM56 series aero-engines [1], and the stress was computed under the different temperature fields, operating speeds and non-linear contacting. The design technologies were summarized for the sealing disk-baffle integrated structure. The results provided bases and references for structure design and engineering applications of the sealing disk-baffle integrated structure.

Crack fault of a centrifugal impeller occurred while working. The finite element model of the impeller was established and vibrational characteristics were analyzed for to find the reason of the crack fault in this paper. The resonance frequencies of the impeller were identified with the help of Campbell diagrams. The modal experiments were carried out with hammering method, the modal parameters were obtained and the correct of the simulations was verified under the same constraints with the FEM model. Computation effort was saved while accuracy was retained making use of the cyclic symmetry technique in ANSYS. The results showed that simulating results agreed well with that of the experiments.

In this paper, numerical and experimental researches were conducted to explore dynamic characteristics of the floating-ring squeeze film damper. The influences of the eccentricity, radial clearance and width of oil film were considered. Reynolds equations of the inner and outer oil film were derived and solved by finite difference method and SOR-Newton method to obtain pressure distribution of the oil film and thus the equivalent stiffness and damping. Effectiveness of the numerical research was validated by experimental results.

The membrane disc coupling has the ability to transmit higher power under high-speed rotation. It also has the ability of compensation angular and radial displacement. The finite element model of the coupling was established and vibrational characteristics were analyzed. The modal experiments were carried out with hammering method, the modal parameters were obtained and the correct of the simulations was verified under the same constraints with the FEM model. The results showed that simulating results agreed well with that of the experiments.