Rotor Deformation Research Articles

Rotor Deformation Impact on Operating Characteristics of IPM Motor Under High-Speed Conditions

Rotor Deformation Impact on Operating Characteristics of IPM Motor Under High-Speed Conditions

Design and Optimization of a Bennett–Spherical Scissor Mechanism Suitable for Driving Aerial–Aquatic Rotor Deformation

Design and Optimization of a Bennett–Spherical Scissor Mechanism Suitable for Driving Aerial–Aquatic Rotor Deformation

Effects of Volute Structure on Energy Performance and Rotor Operational Stability of Molten Salt Pumps

A double-volute molten salt pump with two outlet pipes is proposed based on the original pump model. A numerical approach coupling finite element analysis and computational fluid dynamics (CFD) is implemented to investigate the operational stability and energy performance of two molten salt centrifugal pumps for high-temperature molten salt. The entropy production of the single-volute and double-volute molten salt pumps is investigated. The effects of the volute structures on the mechanical behavior of the impeller and shaft are considered. According to the findings, the local entropy production in the molten salt pump is dominated by the local pulsating entropy production (Spro-T), with the double-volute scheme achieving reduced energy loss. A visualization of the flow field and the local entropy production rate (LEPR) distributions indicate that the LEPR is positively correlated with the complexity of the flow, and higher levels of turbulence intensity lead to greater LEPR. The double-volute scheme enhances the complexity of the flow in the impeller, resulting in an increase in the LEPR compared with the single-volute design. However, the LEPR in the whole double-volute molten salt pump is reduced compared with the single-volute design. It is discovered that the double-volute molten salt pump experiences a less radial hydraulic force. Although the double-volute design has a slightly higher maximum equivalent stress on the impeller than the single-volute scheme, the rotor deformation is significantly less. In general, the double-volute scheme reduces energy loss and ensures better structural stability.

Support Force and Load Distribution Analysis of Angular Contact Ball Bearing Considering Rotor Deformation

Support Force and Load Distribution Analysis of Angular Contact Ball Bearing Considering Rotor Deformation

Optimal phase compensation for a rotor-AMB system considering interface contact

Rotor-Active magnetic bearing (rotor-AMB) systems offer significant advantages in power consumption and are increasingly being applied in fluid machinery. However, in such machinery, the impeller and the rotor are commonly connected by bolt fastening. Once a certain pre-tightening force is applied to the bolted connection and the interface contact between the rotor and the impeller is formed, the flexible modal vibration will be excited when the rotor is levitated. The conventional Proportional-Integral-Derivative (PID) controller is limited in this vibration suppression and it is essential to increase the damping at bending mode to inhibit vibration. However, the calculation of the optimal phase compensated is based on the rotor-AMB model considering interface contact. In this work, the effect of the interface contact is equivalent to massless spring units, and the disturbance generated by spring units is acted upon the mechatronic system in the way of positive feedback. The detailed description of the transfer function from the disturbance to rotor deformation at fourth bending mode is obtained by theoretical model and system identification. The optimal phase of the system needed to inhibit the disturbance is determined by minimizing the gain of the transfer function at fourth bending mode. A combination of PID control and phase compensation is implemented in the experiment. The results show that the optimal phase is 50° as the calculation and the optimal phase compensation control can sufficiently inhibit the modal vibration.

The Loss and Efficiency Analysis and Research of Interior Permanent Magnet Synchronous Motors for Traction Applications

An IPMSM with I2V type rotor topology structure is proposed, its loss, efficiency and torque are analyzed and compared with V and IV type. Firstly, the optimized rotor topology structures are used to analyze the no-load air-gap flux density waveform and harmonic contents of the IPMSM. The results show that the THD of the no-load air-gap flux density with the I2V type is the smallest and the sinusoidal degree of the waveform is the highest. Secondly, the loss of the IPMSM with optimized rotor topology structures are analyzed and compared. Compared with the other two rotors, the results show that the iron loss of the IPMSM with the I2V type is the smallest. The iron loss of the IPMSM with I2V type is significantly less than that of the other two rotors especially under the deep flux weakening conditions. The output torque of the IPMSM under different current angles, current densities and speed are analyzed and compared. The results show that the torque performance of the IPMSM with I2V type is better than the other two rotors. this paper proposes a simple and effective method to optimize the position and diameter of the magnetic isolation holes by establishing a parameterized model. The results show that the torque ripple and cogging torque with the further optimized I2V type rotor topology structure are greatly reduced, the iron loss and magnet loss are also effectively reduced. Finally, the von Mises stress and the total displacement of the rotor deformation of the IPMSM with the further optimized I2V type under different working conditions are verified by finite element analysis. The results show that the rotor will not rupture, the displacement is small enough to avoid the touch between stator and rotor.

Nonuniform Clearance Effects on Pressure Distribution and Leakage Flow in the Straight-through Labyrinth Seals

Straight-through labyrinth seal is a simple and reliable noncontact seal structure widely used in aeroengines. During the actual operation of aeroengines, the labyrinth seal clearance might experience a nonuniform variation in the flow direction due to asymmetric structure and uneven temperature. In order to characterize the degree of nonuniformity, the nonuniformity coefficient is defined in current paper. The effect of nonuniform causes (rotor deformation or stator deformation), nonuniform type (convergent clearance or divergent clearance), and nonuniformity coefficient (nonuniformity degree) is carefully studied by numerical simulation. Comparative analysis has shown that there is no obvious difference in flow coefficient (less than 0.8% in current studies) between two nonuniform causes. As for nonuniform type, the nonuniformity impact of divergent type on the flow coefficient is more significant than that of convergent type, as a result of stronger axial inertia. Pressure distributions of teeth cavities indicate that the total pressure drop of the divergent type is more obvious than that of the convergent type when the pressure ratio is the same. With the same dimensionless minimum tip clearance, clearance nonuniformity would result in the increase of leakage flow of the straight-through labyrinth, particularly for the condition with small pressure ratio, large circumferential Mach number, and small dimensionless minimum tip clearance. When the nonuniformity coefficient is within the range of -0.1 to 0.1, the variation curves of nonuniformity impact factor versus the nonuniformity coefficient almost coincide (the maximum deviation is no more than 1.2%) under different operation conditions (Reynolds number, pressure ratio, circumferential Mach number, and dimensionless minimum tip clearance). Current work proves it that the effect of seal clearance nonuniformity on the leakage flow requires special attention for the refined design of aeroengines.

Investigation of radial gap size change under load and the impact on performance for a twin screw compressor using numerical simulation

Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM) are common and validated tools in research and industry for solving fluid flow or performing structural analysis respectively. Despite being rather challenging, also the numerical simulation of screw compressors benefits from development and enhancement of numerical models, tools and methodologies. Differences between the real machine and the numerical model are inevitable, yet increasing accuracy and prognosis quality are desired by refining existing models and accounting for specific phenomena.Clearances within the working chamber (mainly intermesh clearance between rotors and axial and radial gaps between rotors and housing) strongly affect the flow characteristics, efficiency and thus the overall compressor performance. These clearances change under operating conditions because of thermal expansion or due to forces acting on the structure, whereas the clearance size is often only known for the reference state out of operation. The extent of deformation and the quantification of the resulting clearances is therefore of high interest in order to get the numerical model closer to real operating conditions.In this paper numerical simulation was used to determine the change in radial gap size between rotors and housing when the compressor is running and exposed to thermal and pressure loads. For a specific operating point, a 3D-CFD simulation for a 4-6 twin screw compressor with SRM profiles was conducted for the undeformed reference compressor geometry to calculate the flow field within the machine. Also, the temperature field within the housing and rotor solids was computed using the Conjugated Heat Transfer (CHT) method. The temperature and pressure fields were then submitted to the FEM solver to compute the deformation of rotors and housing. The results of this structural analysis served as input for a modification of geometry and numerical grids to account for the change in radial gap size. A re-run of the flow simulation in the deformed state enabled to quantify the impact on the machine performance and specific flow quantities. It could be shown that taking deformation into account, the volumetric efficiency is clearly affected.Commercial solvers from Ansys were utilized for solving fluid and structure. The spatial discretization of the fluid volume around the rotors was realized by employing pre-generated grids using the mesh generator TwinMesh. Here, the rotor deformation can be defined in dependence of the axial position. The mesh of the housing maintained unchanged for all CFD simulations as a resulting gap size was determined by considering housing and rotor deformation relative to each other.

Influence of Filament Winding Tension on the Deformation of Composite Flywheel Rotors with H-Shaped Hubs.

The residual stress plays an important role in composite flywheel rotors composed of filament windings. The fiber tension during high-prestressed winding is the main source of the rotor deformation and residual stress of composite layers. In this study, the effect of the winding tension gradient on deformation was monitored in real-time. Two types of in-plane winding tension fluctuation methods were developed to investigate the effect of tension on deformation. Online and offline measurements were performed for the strain acquisition. A wireless strain instrument was used for online deformation monitoring and a laser scanner was used for the offline surface reconstruction. Additionally, different filament winding strategies were carried out to improve the efficiency of the winding tension by finite element analysis. The results indicated that the deviation between numerical and experimental results was within 8%. Based on the proposed numerical method, the influence of the in-plane and out-of-plane winding tension gradient distributions on the rotation process of the H-shaped rotor was analyzed. An in-plane winding strategy with variable tension was developed, which increased the initial failure speed by 160%.

Study on screw rotor thermal machining method of single screw compressor

Single screw compressor (SSC) is a type of rotary compressor with excellent performance. However, under high temperature conditions, the hot deformation of the screw rotor and the star wheel cause the change of the gap of the meshing pairs, which seriously degrades the compressor performance. In order to solve the problem of the gap variation of the meshing pairs, a new hot-state machining method is proposed to study the deformation characteristics of the screw rotor in the hot-state machining process, which provides some reference data for the pre-deformation of the rotor in the machining process. Numerical calculation model of thermal machining process for screw rotor was established by using finite element method. With the validated model, the deformation characteristics in the process of hot working were studied by changing the number of heating holes, diameter of heating holes and temperature of heating holes. Results show that screw rotor deformation will increase with the increase of heat source temperature and diameter, and the deformation distribution of the screw rotor is not significantly affected by the heat source temperature and diameter, but will be more uniform with the increase of heat source quantity. The research work in this paper can provide theoretical basis for hot machining of screw rotor for SSC.

Flutter study of flapwise bend-twist coupled composite wind turbine blades

Bending-twisting coupling induced in big composite wind turbine blades is one of the passive control mechanisms which is exploited to mitigate loads incurred due to deformation of the blades. In the present study, flutter characteristics of bend-twist coupled blades, designed for load alleviation in wind turbine systems, are investigated by time-domain analysis. For this purpose, a baseline full GFRP blade, a bend-twist coupled full GFRP blade, and a hybrid GFRP and CFRP bend-twist coupled blade is designed for load reduction purpose for a 5 MW wind turbine model that is set up in the wind turbine multi-body dynamic code PHATAS. For the study of flutter characteristics of the blades, an over-speed analysis of the wind turbine system is performed without using any blade control and applying slowly increasing wind velocity. A detailed procedure of obtaining the flutter wind and rotational speeds from the time responses of the rotational speed of the rotor, flapwise and torsional deformation of the blade tip, and angle of attack and lift coefficient of the tip section of the blade is explained. Results show that flutter wind and rotational speeds of bend-twist coupled blades are lower than the flutter wind and rotational speeds of the baseline blade mainly due to the kinematic coupling between the bending and torsional deformation in bend-twist coupled blades.

Fluid structure interaction analysis of the operating Savonius wind turbine

In the last few decades vertical axis wind turbines (VAWTs) have gained increased interest among researchers worldwide. This paper aims to present full two-way Fluid Structure Interaction (FSI) approach to model operation of the Savonius-type VAWT. The developed methodology couples the set of Unsteady Reynolds Averaged Navier-Stokes Equations (URANS) with the unsteady linear elasticity equations and dynamic mesh approach to comprehensively describe the deformations of the turbine rotor. The obtained results provide detailed information on the unsteady flow fields around the operating wind turbine as well as deformations of a turbine rotor caused by an interaction between solid and flowing air. This allowed us to determine the influence of the unsteady deformations of a turbine rotor on the instantaneous and average performance of a wind turbine. Computations were carried out for the wind speed equal to 15 m/s and the tip speed ratio equal to 0.8. The simulations were performed using the commercial ANSYS software. The obtained results showed that deformation of the turbine rotor increases the wind turbine power coefficient by around 5%. Moreover, it was shown that the centrifugal force has a significant effect on the rotor deformation and turbine operation, hence it cannot be neglected.

Structural characteristics of twin-screw compressor rotor based on thermal-solid coupling method

High-temperature gas will cause stress and deformation of the rotor during the operation of the twin-screw compressor, which will affect the structural performance of the screw rotor. Based on the CFD/CSD coupling solution technology, the method of thermal solid numerical analysis is developed. The fluid control equations are time-averaged differential equations, and the turbulence model is a two-equation Realizable K-ε model. The thermal deformation and thermal stress of the rotor are obtained by solving the structural static equilibrium equation. The reliability of the proposed method is verified by solving the thermal deformation of the L-shaped large-diameter buried pipeline. Finally, the thermal deformation and thermal stress of the rotor under different exhaust pressures and different speeds are mainly studied. Through simulation analysis, the variation law of rotor deformation, stress and modal under different temperature fields of the compressor is obtained, which can provide a certain theoretical reference for the compressor structural design and optimization.

Active vibration control of a rotor bearing system using flexible piezoelectric patch actuators

Rotor vibration control is crucial for the reliability of rotating machines. This article applies active vibration control to reduce the vibration of a rotor bearing system using flexible piezoelectric patches as actuators mounted on the shaft external surface. The patches reduce the vibration due to unbalance forces by generating bending moments to counteract rotor deformation. An active vibration control system is designed based on a full-state linear quadratic regulator controller. Since proximity probes are used to measure the lateral vibrations of the rotor at few shaft positions, an observer is designed to estimate the unmeasured vibrations. The weighting matrices required by the linear quadratic regulator controller are selected by trial and error so that the displacement amplitudes are reduced to a minimum and the actuation voltages remain within the limitations defined by the manufacturer of the used patches. Simulated responses demonstrate the effectiveness of the designed controller in attenuating the lateral vibration of the rotor bearing system when using two actuating voltages. The vibration response is reduced for the steady-state condition and during run-up particularly at the first critical speed.

Force Analysis for a Variable-Pitch Rotor Meshing Pair in Twin-Screw Vacuum Pump Generating on CNC Turning Machine

The variable pitch twin-screw vacuum pump has more advantage than the uniform pitch twin-screw vacuum pump. Its energy efficiency and volumetric compression ratio are specifically high. Under the cyclic gas pressure and working temperature, the rotors of vacuum pump often deform and interfere that lead to noise, vibration and rotor abrasion. In this paper, a 3D model of the variable pitch rotor generating by CNC turning process is constructed to reasonably estimate the rotor load and deformation in operation. The contact force have been analyzed to show the advantages of variable pitch rotors.

Rotor optimization for the improvement of ultrasonic motor performance

The rotor deformation of an ultrasonic motor is an important factor affecting its performance. However, little research focuses on the relationship between the rotor deformation and motor performance. This paper provides an approach to improve the ultrasonic motor's output properties by changing the rotor's size from the view of proper rotor deformation and better stress distribution on the interface. First, a thin shell structure is introduced to study the deformation of the rotor. A finite element model of the motor is built in COMSOL Multiphysics software for the contact analysis of the stress distribution. Then, the optimized ranges of parameters are determined by simulation. Frictional experiments are conducted to verify the feasibility of the rotor under the optimized size. Finally, the performance experiments of a stator corresponding to different sizes of rotor are carried out. The experimental results show that the speed, the power and the efficiency of the optimized rotor are all increase. These results prove the effectivity of the new approach to improving the performance of the ultrasonic motor.

A Novel Correlation Model for Horizontal Axis Wind Turbines Operating at High-Interference Flow Regimes

Driven by economics-of-scale factors, wind-turbine rotor sizes have increased formidably in recent years. Larger rotors with lighter blades of increased flexibility will experiment substantially higher levels of deformation. Future turbines will also incorporate advanced control strategies to widen the range of wind velocities over which energy is captured. These factors will extend turbine operational regimes, including flow states with high interference factors. In this paper we derive a new empirical relation to both improve and extend the range of Blade Element Momentum (BEM) models, when applied to high interference-factor regimes. In most BEM models, these flow regimes are modeled using empirical relations derived from experimental data. However, an empirical relation that best represents these flow states is still missing. The new relation presented in this paper is based on data from numerical experiments performed on an actuator disk model, and implemented in the context of a novel model of the BEM family called the DRD-BEM (Dynamic Rotor Deformation—BEM), recently introduced in Ponta, et al., 2016. A detailed description of the numerical experiments is presented, followed by DRD-BEM simulation results for the case of the benchmark NREL-5MW Reference Wind Turbine with this new polynomial curve incorporated.

A Knowledge- and Data-Driven Soft Sensor Based on Deep Learning for Predicting the Deformation of an Air Preheater Rotor

In industrial processes, some important process variables cannot be measured directly by hardware sensors for technical or economic reasons. Soft sensors estimate these key variables using some other easily measured variables by building a mathematical model. A novel knowledge- and data-driven soft sensor is proposed in this paper to predict the deformation of an air preheater rotor in a thermal power plant boiler. Two submodels were constructed, including the knowledge-driven submodel, derived from all the available domain knowledge, and the data-driven submodel, constructed solely from the data. The two submodels were integrated with a mass balance model. A mathematical model based on technical expertise in predicting rotor deformation, named the Lab model, was used as the knowledge-driven submodel, and a deep learning model based on stacked autoencoders (SAE) was used as the data-driven submodel. To improve the performance of the model, the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm was adopted to optimize the SAE parameters. The experimental results demonstrate that, compared with the common knowledge-driven (KDM) and data-driven (DDM) models, the proposed Lab-stacked autoencoders (L-SAE) model is able to provide a higher predictive accuracy for the air preheater rotor deformation and inherits the advantages of both the KDM and DDM.

Thermal stress deformation prediction for rotary air-preheater rotor using deep learning approach

Failures often occur in the seal clearance measuring sensor due to the harsh operating conditions of the rotary air-preheater in power plant boilers. Therefore, it is necessary to predict the rotor deformation to eliminate the effects of failures on the gap control system. An air-preheater rotor thermal stress deformation prediction method is proposed in this paper based on deep learning. Firstly, a stacked auto-encoder (SAE) is constructed and trained to learn the feature information which is hidden within the input data (the temperature of flue gas side inlet, air side outlet, flue gas side outlet, air side inlet); then, an Elman neural network is constructed and trained using the output of the encoder part of the well trained stacked auto-encoder to predict rotor deformation. Simulation and experimental results show that the proposed SAE-Elman prediction method can obtain the effective feature representation and has better prediction precision compared with other traditional prediction methods.

Thermal stress deformation prediction for rotary air-preheater rotor using deep learning approach

Failures often occur in the seal clearance measuring sensor due to the harsh operating conditions of the rotary air-preheater in power plant boilers. Therefore, it is necessary to predict the rotor deformation to eliminate the effects of failures on the gap control system. An air-preheater rotor thermal stress deformation prediction method is proposed in this paper based on deep learning. Firstly, a stacked auto-encoder (SAE) is constructed and trained to learn the feature information which is hidden within the input data (the temperature of flue gas side inlet, air side outlet, flue gas side outlet, air side inlet); then, an Elman neural network is constructed and trained using the output of the encoder part of the well trained stacked auto-encoder to predict rotor deformation. Simulation and experimental results show that the proposed SAE-Elman prediction method can obtain the effective feature representation and has better prediction precision compared with other traditional prediction methods.