Response analysis of rotor system subjected to the base movements in a large rotational machinery is a complex high-dimensional nonlinear problem. In this paper, rotor system of a centrifugal pump with a pair of oil lubricated bearings is modeled as a six-degrees-of-freedom nonlinear system by the Lagrange method. The Runge–Kutta–Felburg method with variable step size is applied to solve the equations based both on nonlinear bearing model and on linearized bearing model. Poincaré maps, phase trajectories, bifurcation diagrams, and cascade diagrams are used to illustrate the dynamics of the rotor with the two bearing models. The responses of these two kinds of systems under El Centro seismic wave are obtained. The acceleration data of the seismic wave are used as the input of base movements. The short bearing model is applied to express the nonlinear oil film force. Compared to the system with model of linearized bearing, the nonlinear bearing–rotor system can accurately reflect the dynamics of the system. Furthermore, trigonometric functions are employed to express the base movements, and the responses of nonlinear bearing–rotor system subject to the base movements are obtained. The fast Fourier transform is used to analyze the nonlinear bearing–rotor system with effects of the base movements. The results reveal not only the dynamic behavior of the rotor of the centrifugal pump supported by two nonlinear bearings, but also the responses of the nonlinear bearing–rotor system with the combined effects of centrifugal force and base movements.

The computational fluid dynamics (CFD) combined with radial basis function (RBF) method were adopted to obtain the response surface of the Muszynska nonlinear seal force model coefficient with two variables: eccentricity and rotation speed. During the implementation of the simulation, three coefficients of the seal force model were calculated in each sub-step according to the current state of the rotor-bearing seal system; following which the rotor dynamics analysis with varying parameters was realized. As with the traditional constant coefficient method, the first-order critical speed of the system was obtained, and the bifurcation point and oil film whirl of the system response were identified. The difference is that the coefficients of the traditional method ordinarily do not change with the state of the system. Comparing the results of the varying parameter method with those of the traditional method, it can be seen that the speeds of the system corresponding to the bifurcation and oil film whirl are different. The varying parameter rotor dynamics simulation method proposed in this paper provides a new way of analyzing the nonlinear characteristics of rotor-bearing-seal systems.

The rotordynamics and fluid dynamics of a turbo‐machine considering the effect of fluid‐solid interaction (FSI) are numerically investigated using finite element software ADINA. The iterative method is adopted in computation of coupled fields of displacement and fluid. What distinguishes the present study from previous ones is the use of ADINA′s rotational meshes and the FSI interface that separates the rotor surface from its surrounding fluid. The rotor′s center orbit and frequency response as well as the transient fluid dynamics are obtained with various axial flow speeds. By including real rotating motion of the rotor, this paper presents a better way to solve complicated rotordynamic problems of turbo‐machines that are operated in FSI circumstances.

The stall point of a centrifugal compressor is obtained by CFD method and FFT method, and an experiment in the stall point is carried out. Firstly, the curves of the compressor efficiency and total pressure ratio with flow rate are obtained by the steady CFD analysis. Secondly, according to the curves, the unsteady CFD analysis and frequency signal analysis are carried out at the operation points where stall may occur. Then the stall point of the compressor is obtained. On the basis of the results of numerical analysis, the model machine is used to carry out the test. By comparing the results of the numerical method and the experimental method, the stall is identified at the similar operation point, which proves the effectiveness of the prediction method in this paper.