Rotor System Research Articles

Analysis of noise characteristics of ceramic bearings rotor system in a wide temperature range

Abstract The loosening effect of ceramic bearings in steel seats becomes increasingly pronounced over a wide temperature range as the temperature rises. This leads to more complex bearing movements and more intense contact with the inner walls of the steel seats, significantly impacting the system’s noise characteristics. In the noise model of the ceramic bearing rotor system, the shaft was discretized into elements, and the variable clearance between the bearing and the steel seat due to temperature changes was used as the geometric boundary condition for the outer ring motion. The influence of temperature and clearance on the noise characteristics of ceramic bearings was investigated experimentally. The results indicate that the clearance, by altering the interaction between the bearing and the steel housing, affects the system’s sound radiation. Sound pressure level was positively correlated with temperature increase, and the directionality of the noise also varied with temperature. Following manufacturing requirements, connecting ceramic bearings to the steel housing through an interference fit can effectively mitigate the noise from ceramic bearings. These research findings provide theoretical guidance for the installation and noise suppression of ceramic-bearing rotor systems across a wide temperature range.

Dynamic behaviours of marine rotor-bearing and floating raft-airbag system under coupled heaving and pitching motions

ABSTRACT This paper focuses on examining the influence of coupled heave and pitch motions on the dynamic behaviour of a marine rotor-bearing and floating raft-airbag system. Firstly, a mathematical model of the rotor-bearing system under the above motions was established based on the Lagrange equation, and the equation was solved by the Runge–Kutta method. The results show that the steady-state response of this rotor system changes from a quasi-periodic state to a chaotic one as the rotating speed increases under a single heave or pitch motion and their combinations. Meanwhile, the amplitude of the rotor varies greatly in the case of heave motion, while the pitch motion has a more significant effect on the vibration period of the floating raft. In the case of the coupled heave and pitch motions, both the vibration amplitudes of the rotor and the floating raft increase remarkably, and exhibit a regular large-period motion.

Prediction and control of the vibration radiation noise of a multifunctional straw kneading machine shell

Multifunctional straw kneading machines experience significant issues, such as severe shell vibrations and considerable radiated noise during operation. To accurately predict and control the vibration and radiated noise of the machine shell during the design phase, a thorough analysis and calculation of the excitation sources were conducted. These sources include the pulsating pressure on the casing caused by the internal coupled flow field and the unbalanced dynamic force of the rotor system. A vibration response analysis of the kneading machine shell was carried out, and the results were utilized to determine acoustic boundary conditions. The acoustic transfer vector and modal acoustic transfer vector methods were applied to forecast the vibration radiation noise emitted from the shell numerically. The precision of this noise prediction model and methodology was confirmed through experimental noise measurements, and the influence of each excitation source on the vibration radiation noise of the shell is discussed. The panel acoustic contribution analysis approach was used to optimize the structural design of the kneading machine shell to effectively manage and reduce vibration and radiated noise. The results show that both the numerically predicted and experimentally measured sound pressure levels (SPLs) exhibit consistent trends, with the peak SPL frequencies closely aligned. The maximum discrepancy between the simulated and measured total SPL was 2.42 dB(A), validating the accuracy of the vibration radiation noise prediction model. Following structural modifications, significant reductions in the surface vibration velocity, radiation noise frequency band SPL, and total SPL of the machine shell were observed. The total sound pressure level at the measuring points in front of the pulley, the lower discharge outlet, and the upper discharge outlet are below the 90 dB(A) threshold specified by the national standard. The research findings offer valuable insights into the effective design and noise control of low-vibration radiation noise in similar machinery.

Dynamic characteristics of a complex rotor system supported on active dry friction dampers considering friction-stiffening effects

Dynamic characteristics of a complex rotor system supported on active dry friction dampers considering friction-stiffening effects

Probability Density Evolution and Fractional PID Control of Magnetic Bearing-Rigid Rotor System Influenced by Multisource Stochastic Factors

Magnetic bearings are widely used in engineering for their remarkable advantages of low friction, no wear and high speed. In this paper, the dynamics and control of the magnetic bearing-rigid rotor system under the influence of multisource stochastic factors are studied. Firstly, a model of magnetic bearing-rigid rotor system driven by multiplicative noise and additive noise is established. Secondly, the stationary response probability density function (PDF) of the proposed magnetic bearing system is obtained by using the amplitude envelope stochastic average method. Then we analyze the influence of different system parameters and noise intensity on the magnetic bearing-rigid rotor system, and find that internal stochastic factors are the main factors affecting the stability of the bearing system. Finally, the fractional Proportional Integral Derivative (PID) control of the system is studied. Based on the numerical analysis, we verify the effectiveness of the control strategy and draw the conclusion that adjusting appropriately the parameters of fractional PID controller can make the magnetic bearing system control better.

Research on Rotor Dynamic Characteristics of High Speed Aviation Piston Pump

The high-speed aviation piston pump plays a vital role in hydraulic systems in the aviation field. Extremely complex force situations happen during running operations due to the coupling between multiple components, as a result of the overall dynamic characteristics being complex and changeable, which brings great difficulties and challenges to its performance optimization. Taking the high-speed aviation piston pump as the research object, a mechanical balance equation of the piston based on the dynamic balance method was proposed. The reaction force of the swashplate and the influence of rotational speed and outlet pressure on it were modeled. Through the balance of the system and the component subsystem, the load of the support bearing of the piston pump under different working conditions is analyzed, as well as the influence of the rotational speed and the outlet pressure on the bearing stiffness by the quasi-static method. In addition, the discrete model of the piston pump spindle and the discrete model of the rotor system are established. The accuracy of the model is verified by the finite element method. The maximum error of the spindle discrete model is 6.13%, and the maximum error of the rotor system discrete model is 15.28%. The transfer matrix analysis shows that the working condition parameters have little effect on the critical speed of the spindle and rotor system, and the outlet pressure has a more significant effect than the speed. The research results provide a theoretical basis and analysis method for the dynamic analysis and structural optimization of the high-speed aviation piston pump.

Dynamic Characteristics and Periodic Stability Analysis of Rotor System with Squeeze Film Damper Under Base Motions

Inertial loads induced by base motion excitation introduce significant complexities in equilibrium point determination and linearization of systems incorporating squeeze film dampers (SFDs). The coupled effects of base motion excitation and SFD characteristics on periodic stability have received limited attention in previous investigations. This study investigates the dynamic characteristics and periodic stability of a rotor system with SFD subjected to base motion excitation. A finite element model of the rotor-SFD-support system under non-inertial motion is established. The periodic responses are solved using the harmonic balance method with alternating frequency/time technique (HB-AFT) and the arc-length continuation algorithm incorporating the predictor–corrector method, while system stability is analyzed using Floquet theory and the Newmark method. A systematic parametric study is conducted to investigate the effects of base motion parameters, mass unbalance, and SFD parameters on the system’s periodic response. Results demonstrate that base pitching motion enhances system stability, suppresses bistable responses and jump phenomena, and reduces unstable vibration regions. However, under specific parameter combinations, pitching motion can trigger secondary Hopf bifurcations, leading to quasi-periodic and chaotic motions, among other complex nonlinear behaviors. This research provides theoretical foundations for stability-oriented design optimization of rotor systems with SFDs under base motion excitation.

An Adjustable Elastic Support Structure for Vibration Suppression of Rotating Machinery

Abstract The dynamic characteristic of a rotor-support system plays a crucial role in the operational efficiency and longevity of rotating machinery such as gas turbines. Traditional support structures with the fixed-parameter elastic stiffness have difficulties in adapting to the diverse and complex working conditions of flexible rotating machinery, particularly those that pass through multiple critical speeds. To address rotor resonance and enhance structural reliability, an innovative adjustable elastic support (AES) structure designed to improve the mechanical adaptability of rotors across various speed ranges is investigated in this paper. The AES structure is built upon the conventional squirrel cage elastic support by incorporating a stepper motor. By adjusting the rotation angle of the motor, the effective length of the cage bar can be modified, allowing real-time changes in the support state during rotor operation. This mechanism enables seamless transitions among multiple states: a constant stiffness elastic support, a separate state, or a variable stiffness dynamic absorber that modulates frequencies in real-time by altering the cage bar length. This dynamic capability effectively suppresses resonance peaks caused by mass imbalances. The design and implementation of the AES structure, along with a speed feedback-based adjustment scheme to accommodate the rotor's dynamic characteristics, are discussed. Experimental validation of a multisupport flexible rotor system demonstrates that a maximum vibration can be reduced up to 75%, highlighting its promising potential for engineering applications.

Analytical model of bolted flange with spigot and application to the vibration analysis of a rolling bearing - bolted rotor system with spigot

Analytical model of bolted flange with spigot and application to the vibration analysis of a rolling bearing - bolted rotor system with spigot

Optimizing the Aerodynamic Performance of a Duct–Rotor System for Drones: A Comprehensive Study on the Coupled Parameters

Optimizing the Aerodynamic Performance of a Duct–Rotor System for Drones: A Comprehensive Study on the Coupled Parameters

Determination of the Tail Unit Parameters of Ultralight Manned and Unmanned Helicopters at the Preliminary Design Stage

The 1–2 seat helicopters have developed considerably in recent years. They have a maximum take-off weight of 250 to 750 kg. Most of these helicopters have been converted into unmanned versions. Typically, such UAV models retain the rotor system, power plant, transmission, and empennage of the manned versions. For this reason, statistics and design methods for small manned helicopters are also applied to unmanned versions. The existing methods for selecting helicopter parameters in the preliminary design phase are based on statistical data for heavier-class helicopters. However, the lightest weight class helicopters differ significantly from their heavier counterparts. The analysis shows that the results of parameter selection at the preliminary design stage have an error rate of between 11 and 30%. The main reason for this difference is a scale factor. In this paper, a method for determining helicopter tail unit parameters at the preliminary design stage is presented. The proposed relationships for the horizontal stabilizer, fin, tail boom, and tail rotor parameters are based on an analysis of statistical data from 36 rotorcraft and the author’s design experience. In particular, the article presents the relationships between the geometric parameters of the empennage and tail rotor from other helicopter data. The relationships presented also allow the mass of the tail unit to be determined.

A novel spring-based nonlinear energy sink for torsional vibration suppression of long-shafting rotor system

A novel spring-based nonlinear energy sink for torsional vibration suppression of long-shafting rotor system

Efficient metamodeling and uncertainty propagation for rotor systems by sparse polynomial chaos expansion

Efficient metamodeling and uncertainty propagation for rotor systems by sparse polynomial chaos expansion

Design of an electromagnetically tuned mass damper and its experimental study on vibration reduction for flywheel rotor systems

Design of an electromagnetically tuned mass damper and its experimental study on vibration reduction for flywheel rotor systems

Research status and dynamic analysis of damping and vibration reduction technology of rotating machinery rotor system

Research status and dynamic analysis of damping and vibration reduction technology of rotating machinery rotor system

Radially-azimuthally discretized blade-element momentum theory for skewed coaxial turbines

Marine hydrokinetic energy from rivers, tides, and ocean currents is largely underutilized. Dual rotor coaxial turbines can harness this energy more effectively than single-rotor designs – even more so when the turbine orientation is skewed against the flow. A novel blade-element momentum theory (BEMT) model which incorporates radial and azimuthal discretization, RAD-BEMT, has been developed to explicitly incorporate the effects of nonuniform inflow conditions into turbine. By compounding RAD-BEMT with a streamtube mass continuity relationship and generator configuration behavior, a solution scheme to determine the power of a coaxial rotor system in skew was developed – removing simplifying assumptions utilized in previous literature. This generalized methodology was validated against experimental data for coaxial turbines in water and air. RAD-BEMT has established a low-order foundation to analyze the distributions of loading, efficiency, and local performance, amongst other metrics, of coaxial or single rotor devices in complex inflows. This foundation can support early prototyping for dynamics and control, minimizing the need for complex computational techniques like CFD. A case study of a coaxial turbine geometry was performed with the RAD-BEMT solution scheme to demonstrate its application and the insights it can provide for coaxial turbine design.

Transient flow characteristics and energy loss investigation in a desalination energy recovery device under rotor system axial sliding conditions: Focusing on the turbine side

Transient flow characteristics and energy loss investigation in a desalination energy recovery device under rotor system axial sliding conditions: Focusing on the turbine side

Modeling of bolted connection characteristics and nonlinear response analysis of a rotor system under the effect of bolted connection and maneuver loads

Modeling of bolted connection characteristics and nonlinear response analysis of a rotor system under the effect of bolted connection and maneuver loads

Numerical study on the dynamic characteristics of the drive shaft system with diaphragm crack

The diaphragm coupling is widely used in the drive shaft system, which suffer from the crack at the waist of the diaphragm in long-term and high-speed working environments. However, the effect of the diaphragm crack (DC) on the dynamic characteristics of the drive shaft system. To solve the above issues, this paper researched the effect of the DC on the dynamic characteristics of the drive shaft system. The time-varying stiffness of the diaphragm group (DG) with crack was calculated considering friction. The calculation results indicated that the DC causes a decrease in the stiffness of the DG and introduces multiple higher-order harmonic components into the stiffness of the DG. The effect of the DC on the dynamic characteristics of the system was conducted. The accuracy of the system model is verified by comparing the critical speed results of the software and theory. The DC caused 2×, 4× super-harmonic resonance phenomenon. Meanwhile, the frequency-domain response of the system included a significant 2× super-harmonic component and also a significant 4× super-harmonic component at low speed. The super-harmonic components in the system response are introduced by the higher-order harmonic components in the time-varying stiffness of the DG, then leading to the super-harmonic resonance and irregular axis trajectory. The effect of the DC is significantly different from that of the open and breathing cracks in the rotor system. In engineering, it is possible to comprehensively observe the axis trajectory, super-harmonic resonance phenomenon, 2× and 4×super-harmonic components, and the 180° flip of the axis trajectory through the 1/2 first critical speed is used to determine whether the diaphragm has a crack.

Modal analysis of multi-disk rotor system

Modal analysis of multi-disk rotor system