Research on Vibration Suppression Method Based on Coaxial Stacking Measurement

A dynamic analysis model of the unbalanced vibration response of a single-rotor system is established to study the corresponding mechanism of the unbalanced excitation force and vibration response caused by the deviation of the rotor mass centroid in this paper, and finally to achieve the combined rotor vibration suppression. First, the installation of multi-stage rotors during vibration was studied, and the rotor mass centroid transfer model in the rotating coordinate system was established to obtain the unbalanced excitation force vectors of the rotors at all levels based on the traditional stacking assembly method and axiality measurement. Second, the rotor unbalance excitation force vectors were substituted at all levels to establish the finite element analysis model of the single-rotor system. Finally, a simulation analysis was carried out for the stacking assembly of the three-stage rotor, and the rotor test piece was used for the vibration experiment. The results show that the optimal assembly phase of the multi-stage rotor obtained by the dynamic analysis model of the unbalanced vibration response of the single-rotor system can effectively suppress the vibration of the combined rotor.

Implementation of Variable Blade Inertia in OpenFAST to Integrate a Flywheel System in the Rotor of a Wind Turbine

In this paper, the integration of the dynamic behavior of the flywheel system into the load simulation tool OpenFAST is presented. The flywheel system enables a wind turbine to vary the inertia of its rotor blades to control the power production and, most importantly, to affect the vibratory behavior of wind turbine components. Consequently, in order to simulate the behavior of a wind turbine with a flywheel system in its rotor, the variable blade characteristics need to be considered in the load simulation tool. Currently, computer-aided engineering tools for simulating the mechanical loads of wind turbines are not designed to simulate variable blade inertia. Hence, the goal of this paper is to explain how variable inertias of rotor blades are implanted in such load simulation tools as OpenFAST. OpenFAST is used because of it is free, publicly available, and well documentation. Moreover, OpenFAST is open source, which allows modifications in its source code. This add-on in the load simulation is applied to correct rotor mass imbalance. It can also be applied in many cases related to the change in the inertia of wind turbine rotor blades during its operation as, for example, atmospheric ice accretion on the blades, smart blades, etc.

Dynamic modeling of rotor-bearing-housing system with local defect on ball bearing using mass distribution and energy methods

The rotor-bearing-housing system is widely used in rotating machines, which influences the performance of the whole machine. Considering the distribution of rotor mass, the rotor-bearing-housing system with local defect in the outer ring is modeled based on the energy method. In order to make the model agree well with the experimental results, a new rotor mass distribution method was introduced in the modeling process. The simulated vibration signal was obtained by solving the dynamic equations with the Runge-Kutta method. The vibration responses of rotor-bearing-housing system under different distributed disks at both drive end and fan end are simulated. In the simulation results, the outer ring fault signal at the drive end and the vibration signal at the fan end are compared with the experimental signals to discuss the influence of rotor mass distribution on the vibration response of the bearing at both ends of the system. The results show that the simulation signal generated by the dynamic model of the rotor-bearing-housing system with a more uniform rotor mass distribution is more consistent with the experimental signal. The vibration response of the faulty bearing at drive end is compared at different defect sizes, and the variation trend of the amplitude of their characteristic frequency is obtained. This method is helpful for structural optimization and fault diagnosis of the rotor-bearing-housing system.

Structural design and optimization of a series of 13.2 MW downwind rotors

The quest for reduced LCOE has driven significant growth in wind turbine size. A key question to enable larger rotor designs is how to configure and optimize structural designs to constrain blade mass and cost while satisfying a growing set of challenging structural design requirements. In this paper, we investigate the performance of a series of three two-bladed downwind rotors with different blade lengths (104.3-m, 122.9-m, and 143.4-m) all rated at 13.2 MW. The primary goals are to achieve 25% rotor mass and 25% LCOE reduction. A comparative analysis of the structural performance and economics of this family rotors is presented. To further explore optimization opportunities for large rotors, we present new results in a root and spar cap design optimization. In summary, we present structural design solutions that achieve 25% rotor mass reduction in a SUMR13i design (104.3-m) and 25% LCOE reduction in a SUMR13C design (143.4-m).

Bifurcation and Nonlinear Behavior Analysis of Dual-Directional Coupled Aerodynamic Bearing Systems

Dual-directional coupled aerodynamic bearing (DCAB) systems have received considerable attention over the past few years. These systems are primarily used to solve air lubrication problems in high-precision mechanisms and equipment that run at a high rotational speed and require high rigidity and precision. DCABs have the advantages of axial and radial thrust and provide high rigidity, dual-directional support, and high load-carrying capacity. In DCAB systems, the nonlinearity of the air film pressure and dynamic problems, such as critical speed, unbalanced air supply, or poor design, can cause the instability of the rotor-bearing system and phenomena such as nonperiodic or chaotic motion under certain parameters or conditions. Therefore, to investigate what conditions lead to nonperiodic phenomena and to avoid irregular vibration, the properties and performance of the DCAB system were explored in detail by using three numerical methods for verifying the accuracy of the numerical results. The rotor behavior was also studied by analyzing the spectral response, the bifurcation phenomenon, Poincaré maps, and the maximum Lyapunov exponent. The numerical results indicate that chaos occurs in the DCAB system for specific ranges of the rotor mass and bearing number. For example, when the rotor mass (mr) is 5.7 kg, chaotic regions where the maximum Lyapunov exponents are greater than 0 occur at bearing number ranges of 3.96–3.98 and 4.63–5.02. The coupling effect of the rotor mass and bearing number was also determined. This effect can provide an important guideline for avoiding an unstable state.

Physical basis of rolling bearing vibration formation of structural

The problem of increasing the reliability of detecting defects, both in new rolling bearings and the ones having already been in operation is current. The article describes the physical foundations of vibration of rolling bearings, caused by the different dimensions of the rolling elements and increased microwaves of the rings. A classification of rolling bearing defects was proposed, as well as calculation formulas for vibration frequencies corresponding to the indicated defects. It is shown that the vibration level at the overturning frequency depends on the gap size and the rotor mass. As an example, possible defects of rolling bearing No.310 were considered and their vibration frequencies were calculated. The frequency range in which defects of the rings and rolling elements appear was installed. An explanation of the reasons for the occurrence of high-frequency vibration was given. The combination of defects in the rolling elements of different dimensions and imbalance in the rotor causes the intensive development of microshells on the rolling bearing rings. Examples of experimental vibroacoustic characteristics were given to illustrate the physical processes of vibration in rolling bearings with various defects.

TURBODYNA: Centrifugal/Centripetal Turbomachinery Dynamic Simulator and Its Application on a Mixed Flow Turbine

One-dimensional (1D) modeling is crucial for turbomachinery unsteady performance prediction and system response assessment. The purpose of the paper is to describe a newly developed 1D modeling (turbomachinery dynamic simulator (TURBODYNA)) for turbomachinery. Different from classic 1D modeling, in TURBODYNA, rotor has been meshed and its unsteadiness due to flow field timescale is considered. Instead of direct using of performances maps, source terms are added in Euler equation set to simulate the rotor. By comparing 1D modeling with three-dimensional (3D) computational fluid dynamics (CFD) results, it shows that rotor unsteadiness is indispensable for a better prediction. In addition, different variables response to pulse differently. In the rotor, mass flow is close to quasi-steady while entropy is significantly unsteady. TURBODYNA can capture these features correctly and provide an accurate prediction on pressure wave transportation.

TURBODYNA: Centrifugal/Centripetal Turbomachinery Dynamic Simulator and its Application on a Mixed Flow Turbine

1D modelling is crucial for turbomachinery unsteady performance prediction and system response assessment. The purpose of the paper is to describe a newly developed 1D modelling (TURBODYNA) for turbomachinery. Different from classic 1D modelling, in TURBODYNA, rotor has been meshed and its unsteadiness due to flow field time scale is considered. Instead of direct using of performances maps, source terms are added in Euler equation set to simulate the rotor. By comparing 1D modelling with 3D CFD results, It shows that rotor unsteadiness is indispensable for a better prediction. In addition, different variables response to pulse differently. In the rotor, mass flow is close to quasi-steady while entropy is significantly unsteady. TURBODYNA can capture these features correctly and provide an accurate prediction on pressure wave transportation.