Rotor Shape Research Articles

The influence of the rotor shape on the efficiency of the hydrodynamic heater

The paper discusses issues related to the design of a hydrodynamic throttle type heater. The maximum angular velocities for cylindrical and conical shapes are determined from the condition of non-spilling of liquid from a rotating vessel. Theoretical studies have shown that the conical shape of the skirt is more optimal, since with an increase in the liquid level in the vessel within 0.02–0.09 m, the angular velocity decreases from 37.566 rad/s to 17.709 rad/s, respectively. In addition, with a taper of the vessel walls of 5° and a liquid level height of 0.02 m, the volume of the liquid is 11.0·10–5 m3. If to increase the liquid level to 0.09 m, then the volume of liquid will increase to 55.0·10–5 m3. At a taper of 10°, respectively, there is also an increase in the volume of liquid from 6.0·10–5 m3 to 42.0·10–5 m3. To establish a small increase in the temperature of the liquid when it is forced through the throttle holes, a transparent mock-up was made. Experimental studies have shown the locking of air during the formation of a ring of liquid in the rotor cavity. In addition, it was found that the smaller the inner radius of the liquid ring, the higher the temperature of the pressed liquid through the throttle openings. For this purpose, a system for removing air from its rotor was provided in the hydrodynamic heater. When the rotor is running, the lateral outer walls of the conical skirt interact with the liquid, forcing it to rotate. The rotating liquid, rising along the walls of the housing, begins to interact with the lower part of the rotor, which negatively affects the operation of the hydrodynamic heater as a whole. For this purpose, a special flow directing cylinder was provided in the housing. When the liquid is forced through the throttle opening, there is a decrease in pressure and an increase in the velocity of the liquid. This leads to an increase in its kinetic energy, which is then converted into thermal energy due to friction between the liquid molecules. This principle is used in various systems such as heating systems, industrial processes or laboratory research. However, creating pressure in front of the throttle openings using the inertial forces of a rotating mass of liquid is a promising direction

Modeling and Study of Different Magnet Topologies in Rotor of Low Rating IPMSMs

A study and performance analysis of magnet positions in different topology on the surface of rotor in permanent magnet synchronous motors (PMSMs) based on finite element method is observed here. A 3-phase interior PMSM is numerically simulated with ANSYS Maxwell 2018.1. Differently positioned permanent magnets improve the performance of PMSMs. Apart from handling nonlinear equations, FEM is used for simulation. ANSYS is used to analyze PMSM performance under variable conditions. This proposal examines a three-phase, 0.55 kW PMSM at 220 V, 50 Hz. Here rotor topologies of five types, namely, (i) spoke/tangential, (ii) saturable bridge / u-shape, (iii) V-shape, (iv) radial, and (v) segmented bridge permanent magnet rotor are taken for observation. The motive of this study is to analyze the performance of PMSMs in different rotor designs with different magnet positions. All topologies have been modeled and simulated with ANSYS. Each topology is compared in terms of electromagnetic and mechanical parameters. The 2D model is used to model the distribution of magnetic fields and the performance of operating parameters under transient and steady-state conditions. Magnetic flux, and efficiency are heavily influenced by the rotor shape with the volume of magnet. A study of radial force distribution and mechanical stress across rotor surface is also discussed. Motor performance is affected by the design of PMs.

Rotor pole and stator tooth shaping in FSPM machines for torque performance optimization

Purpose This study aims to obtain the minimum torque ripple at the maximum average torque for Flux-switching permanent magnet (FSPM) machines. Design/methodology/approach This paper is about torque performance optimization of the FSPM machines. To achieve that, finite element analysis and genetic algorithm (GA) are used. Five different designs are simulated, optimized and compared on their air gap flux density, back electromotive force, cogging torque, average torque, torque density and torque ripple. Findings After the thousands of iterations, its proved that all proposed shaping techniques have potential for reducing torque ripple and cogging torque, with slightly reduced average torque. The best design is the joint stator and rotor shaping, Design V, which results in the lowest torque ripple and cogging torque. The techniques should be applicable to FSPMs with other stator slot/rotor pole number combinations. Originality/value In this paper, rotor pole shaping by notching, chamfering and generic shaping, stator tooth shaping and joint shaping techniques are investigated for 12 s/10p FSPM machines. Rotor and stator flanks are optimized separately and jointly, by using finite element analysis and GA for optimization to achieve maximum average torque and minimum torque ripple. Five different design is implemented and compared, respectively.

Dynamic Modeling and Experimental Modal Analysis for the Central Rod-Fastened Rotor With Hirth Couplings Based on Fractal Contact Theory

Abstract The central rod-fastened rotor of gas turbine exhibits pronounced noncontinuous characteristics due to the large number of contact interfaces between the compressor and turbine disks. It is necessary to establish an accurate dynamic modeling method for the central rod-fastened rotor that fully considers the contact surface effect. In this work, the contact behavior of the rough surface is characterized by the fractal theory. The normal and tangential contact stiffness models are developed, and the influence of fractal parameters is discussed. Besides, the finite element model for the central rod-fastened rotor is established by developing an improved contact element considering the equivalent stiffness segment of Hirth couplings. Finally, the proposed model is verified by conducting the modal testing and measuring the first four modes of natural frequencies and modal shapes of the central rod-fastened rotor. The results show that the numerical results are in good agreement with the experimental ones, and the fractal contact model can effectively predict the connection stiffness of Hirth couplings, which in turn improves the simulation accuracy for the modal characteristics of the central rod-fastened rotor and provides a dynamic modeling approach with high efficiency and less computational complexity.

Analysis and optimization of the coupling effect for duct-rotor based on aerodynamic performance

The duct has the potential to provide additional thrust, which can enhance the overall aerodynamic performance of the system. Nonetheless, since the duct and the rotor interact with each other, it is crucial to consider their interaction while optimizing the system for improved performance. This paper presents a parameterization approach for the duct and rotor. Primarily, a rotor space characterization and parameter modeling method that utilizes Bezier curves, class functions/shape functions, and Bernstein polynomials is proposed. Next, the aerodynamic performance of different key factors of the duct-rotor system is calculated and analyzed using a numerical calculation method. The study found that the coupling effect of camber yf and chord length parameter Bc3 had a significant impact on the thrust coefficient, with a contribution rate of 7.3 %. Correspondingly, the coupling effect of camber yf and torsion angle parameter Ba3 had a great influence on the Figure of Merit (FM), with a contribution rate of 7.1 %. The thrust coefficient and FM of the rotor-duct system were optimized by taking the coupling effect into consideration, and the optimized ducted rotor was verified by experimental measurement. The test results shows that the high thrust case achieves a 25.60 % increase in thrust coefficient, while the high-FM case establishes an 8.89 % increase in the FM. This implies that the collaborative optimization based on the coupling effect of duct and rotor shape parameters can effectively improve the system's performance, such as thrust coefficient and Figure of Merit.

Erratum to “Regression model of rotor shape errors based on the ISSA-BP neural network”

Erratum to “Regression model of rotor shape errors based on the ISSA-BP neural network”

Regression model of rotor shape errors based on the ISSA-BP neural network

Regression model of rotor shape errors based on the ISSA-BP neural network

Loss Analysis in Radial Inflow Turbines for Supercritical CO2 Mixtures

Abstract Recent studies suggest that CO2 mixtures can reduce the costs of concentrated solar power plants. Radial inflow turbines (RIT) are considered suitable for small to medium-sized CO2 power plants (100 kW to 10 MW) due to aerodynamic and cost factors. This paper quantifies the impact of CO2 doping on RIT design by comparing 1D mean-line designs and aerodynamic losses of pure CO2 RITs with three CO2 mixtures: titanium tetrachloride (TiCl4), sulfur dioxide (SO2), and hexafluorobenzene (C6F6). Results show that turbine designs share similar rotor shapes and velocity diagrams for all working fluids. However, factors like clearance-to-blade height ratio, turbine pressure ratio, and fluid viscosity cause differences in turbine efficiency. When normalized for these factors, differences in total-to-static efficiency become less than 0.1%. However, imposing rotational speed limits reveals greater differences in turbine designs and efficiencies. The imposition of rotational speed limits reduces total-to-static efficiency across all fluids, with a maximum 15% reduction in 0.1 MW CO2 compared to a 3% reduction in CO2/TiCl4 turbines of the same power. Among the studied mixtures, CO2/TiCl4 turbines achieve the highest efficiency, followed by CO2/C6F6 and CO2/SO2. For example, 100 kW turbines achieve total-to-static efficiencies of 80.0%, 77.4%, 78.1%, and 75.5% for CO2/TiCl4, CO2/C6F6, CO2/SO2, and pure CO2, respectively. In 10 MW turbines, efficiencies are 87.8%, 87.3%, 87.5%, and 87.2% in the same order.

Verification of the self-starting problem of a Vertical Axis Wind Turbine with Inclined Blades

In this paper, a theoretical investigation of the impact of varying the blade inclination angle b on the power coefficient of vertical-axis wind turbines equipped with straight blades has been demonstration, where the inclination angle was modified from twenty-five degrees to eighty-five degrees. Within the framework of this study, the term SS-VAWT was assigned to refer to the rotor which is the subject of the research. The "Multi Stream Tube-MST" mathematical model was used after some of its equations were modified to be consistent with the geometrical shape of the SS-VAWT rotor. A computer program was designed using the "Microsoft Visual Basic" programming language as an application of the mathematical model used, which led to the effectiveness of this program and compared its final results with previous experimental results from other studies, this work was carried out on twelve obligatory SS-VAWT, which are classified into four namely H group which is characterized by rotor high change effect, R group which is characterized by diameter effect, N group which is characterized by number of blades effect and C group influenced by the length of blade chord line. The results are represented by power curves as a function of tip speed ratio. The behavior of the curves for each case was verified and compared to determine the optimum case. All results were taken in the small range of tip speed ratio λ0 extending from 0 to 2.8. Since the Cp coefficient and the λ0 coefficient are dimensionless values, the results can be applied to large-sized air rotors, provided that there is geometric similarity. Because they found that the feather's 45-degree tilt and location reduce the problem of starting self-motion.

Hybrid-Excited Variable Reluctance Resolver With Wide Speed Range

The accuracy of the variable reluctance resolver (VR-Resolver) highly depends on the rotational speed and its rotational speed range is limited by the frequency of the excitation signal. To eliminate the mentioned performance dependency, this paper proposes a hybrid-excited VR-Resolver (HVR-Resolver) with two separate sets of excitation windings: a toroidal excitation winding for the AC excitation supply and an on-tooth one for the DC excitation supply. Similar to the conventional method, the HVR-Resolver is working with AC excitation ON and DC excitation OFF at the low-speed range. For high-speed operation, the excitation switched from AC excitation to DC. By using this technique, the proposed HVR-Resolver is able to accurately estimate the position at a wide speed range. This feature makes the HVR-Resolver an outstanding candidate for EV applications. The proposed design is simulated using time-stepping finite element analysis (TSFEA) in order to study the performance at both low-speed and high-speed ranges with different rotor pole numbers. In addition, an optimization process is conducted to find the best rotor shape factors. The experimental test on the proposed HVR-Resolver indicates a close agreement between simulation and experimental results.

A Deep Learning Approach to Optimize Airfoil Shape for Reduced Trailing Edge Noise in Urban Air Mobility Rotors

The objective of this research is to optimize the airfoil shape of UAM VTOL rotors for trailing edge noise reduction. Our study focuses on employing deep learning techniques for airfoil shape optimization with an emphasis on noise reduction. We implement a neural network that combines a Variational Autoencoder and Generative Adversarial Networks to learn the representation of airfoil shapes. The generated airfoil shapes are then evaluated for aerodynamic performance using XFOIL and trailing edge noise using acoustic diffraction model. The optimization process employs a Particle Swarm Optimization algorithm to find optimal latent features for airfoil generation. The results show that the optimized airfoil shapes have improved aerodynamic performance and reduced noise levels compared to the airfoil VR-12 used in NASA's conceptual UAM. These findings demonstrate that our optimization process has the potential to reduce trailing edge noise while ensuring enhanced aerodynamic performance, which warrants further investigation.

Investigation of the impact of rotor shaping on the torque and radial force harmonics of a V‐shape interior permanent magnet synchronous machine

AbstractThis paper introduces a technique aimed at improving the performance of an interior permanent magnet synchronous machine (IPMSM) by reducing torque ripple and radial force harmonics. Unlike conventional IPMSMs, the proposed method employs a variable airgap length that is defined by a mathematical function. Two distinct rotor shapes are investigated to determine the most efficient design. Finite Element Analysis is employed to assess both the electromagnetic and mechanical attributes of the proposed motors. It compares the results for three operating points of the shaped motor with those of a conventional one. The investigation delves into the influence of rotor geometry on key output parameters, including Back Electromotive Force (back‐EMF) harmonics, average torque, cogging torque, torque ripple, efficiency, power factor, and radial force harmonics. The findings indicate that optimising rotor shape can significantly enhance IPMSM performance by reducing torque ripples and radial force harmonics, while simultaneously increasing average torque and efficiency at different operating points.

Design and Cogging Torque Reduction of Radial Flux Brushless DC Motors with Varied Permanent Magnet Pole Shapes for Electric Vehicle Application

Brushless direct current motors have more attractive features, making them a promising solution for electric vehicle applications. A 1 kW, 510 rpm, 24-slots and 8-pole inner runner type surface permanent magnet mounted radial flux brushless DC motor with seven different permanent magnet pole shape rotor is investigated. Motors with different permanent magnet shape rotors were designed, and finite element modelling and simulation were carried out. For performance comparison, the initial design with a radial-type pole shape was regarded as a reference design. Cogging torque is detrimental to the overall performance of the motor, typically in low-speed applications like electric vehicles. The primary aim of this paper is to reduce the cogging torque & study its effect on the overall performance of the motor and minimize torque ripples with reduced permanent magnet requirements. The proposed designs are analyzed in terms of cogging torque, flux density, torque, efficiency, flux linkage and back-EMF. The comparative analysis shows that the motor with bump-shaped permanent magnet rotor poles has betterperformance than the others.

Технологія відновлення форми ротора гідрогенератора

The object of research in this article is the change in the rotor shape during the operation of hydraulic units. The subject of study in this article is the design and geometric state of the shape of a rotor with irregular geometry of hydraulic generators-engines. This study produced a three-dimensional mechanical calculation of the rotor segment for further use during strain gauge tests. Tasks: investigate the peculiarities of the rotor shape restoration technology; to describe the basic assumptions for the three-dimensional mechanical calculation of rotor deformations at the overspeed; and perform a three-dimensional calculation of rotor movements considering the main forces falling on the pole connection, which are obtained using classical methods. The methods used are: finite element method of mathematical modeling of the thermal stress state of nodes. The following results were obtained: a detailed description of the technological process of restoring the shape of the rotor using the hot wedging method is given. Three-dimensional models of the rotor segment were developed, and a three-dimensional mechanical calculation of this model was performed, as a result of which satisfactory values of the displacement of the rotor of the hydraulic generator at the overspeed were obtained, considering the recovery technology. To reconstruct the rotor rim, it is necessary to heat the rotor rim to a temperature difference between the rim and the frame of at least 60 °C. Next, the hot wedging of the rotor rim is performed with the driving of each of the driving wedges by the same amount, which ensures the creation of the necessary diametrical tension between the rim and the frame of the rotor and avoids the displacement of the rotor rim relative to the frame. The control of this process is performed using strain gauges. If necessary, it is necessary to cool the rotor rim until the temperatures of the rim and the frame of the rotor are equal. Conclusions. The scientific novelty consists of a combined approach to the evaluation of the deformation of the rotor rim after restoring its shape, which includes elements of analytical mechanical calculation and calculation in a three-dimensional setting. The presented technology for the rotor restoration process meets European requirements.

Performance Improvement of Permanent-Magnet-Synchronous Motors through Rotor Shape Optimization of Marine Blowing System with High-Speed Rotation

Currently, research is being carried out on the performance improvement of permanent-magnet-synchronous motors (PMSM) used in air conditioning and blowing systems for marine, as well as structural research, regarding their high-speed operation. Surface-mounted permanent magnet (SPM) motors used in marine propulsion and air-conditioning systems have the advantages of easy rotor manufacturing and a simple structure. However, owing to the structural characteristics associated with attaching a permanent magnet to the surface of the rotor, there is a risk of permanent magnet scattering when turning a rated load at high speed, and the rotor assembly is directly affected by the heat generated in the stator winding. Therefore, in this study, additional protrusions were proposed to prevent rotor scattering during high-speed operations. Additionally, optimization was performed to reduce the torque ripple at the rated load and the total harmonic distortion (THD) of the no-load-induced electromotive-force waveform generated by the protrusion. Consequently, the risk of scattering at high speeds was improved by securing the bonding force of the permanent magnet using the proposed structure, and the THD and torque ripple were reduced compared with those of the basic model through optimization. In addition, rotor structural stress analyses were conducted to solve the problem of scattering at high speeds and eigenmode analysis.

일반, 심구 및 이중 농형 회전자 유도발전기의 계통 연계시 특성 변화에 관한 연구

Induction generators, like induction motors, generate a voltage drop due to a large current during the starting process. Induction generators, like induction motors, have different starting currents and torque sizes depending on the shape of the rotor. The induction generator goes through the motor operating mode before entering the power generating operation mode. Since the current generated in this process is very high, it causes a large voltage drop. Induction machines are usually classified into single-bar cage, deep-bar cage and double-cage types depending on the rotor shape. Each of these rotors has a different magnitude of starting and maximum torque. In this paper, we analyzed whether it is effective in reducing the voltage drop during starting of an induction generator by using the fact that the torque characteristics vary depending on the shape of the rotor.

Analysis of Electromagnetic Parameters of Hybrid Externally Excited Synchronous Motors for Electric Vehicle Applications

This paper presents two different approaches to improve the electromagnetic torque and output power of the hybrid Externally Excited Synchronous Motor (EESM) applied to Electric Vehicles (EVs). An analytical approach is first considered to define the main parameters of the proposed machine. Based on the obtained results from the analytical model, the hybrid EESM is designed with different rotor shapes and step-skewing magnet segments to reduce the total losses and improve torque ripple. Then, Finite Element Analysis (FEA) is applied to compute and simulate electromagnetic parameters, such as the magnetic flux density, mean torque, and output power. The development of these two approaches is validated on an actual EESM machine and the agreement with the theory is shown.

Topologically assisted optimization for rotor design

We develop and apply a novel shape optimization exemplified for a two-blade rotor with respect to the figure of merit. This topologically assisted optimization contains two steps. First, a global evolutionary optimization is performed for the shape parameters, and then a topological analysis reveals the local and global extrema of the objective function directly from the data. This non-dimensional objective function compares the achieved thrust with the required torque. Rotor blades have a decisive contribution to the performance of quadcopters. A two-blade rotor with pre-defined chord length distribution is chosen as the baseline model. The simulation is performed in a moving reference frame with a k−ω turbulence model for the hovering condition. The rotor shape is parameterized by the twist angle distribution. The optimization of this distribution employs a genetic algorithm. The local maxima are distilled from the data using a novel topological analysis inspired by discrete scalar-field topology. We identify one global maximum to be located in the interior of the data and five further local maxima related to errors from non-converged simulations. The interior location of the global optimum suggests that small improvements can be gained from further optimization. The local maxima have a small persistence, i.e., disappear under a small ε perturbation of the figure of merit values. In other words, the data may be approximated by a smooth mono-modal surrogate model. Thus, the topological data analysis provides valuable insight for optimization and surrogate modeling.

Evolutionary optimization of a Savonius rotor with sandeel-inspired blades

A possible way to capture the kinetic energy available in the wind and then convert it into a useful form of energy is to use wind turbines. Out of many kinds of wind turbines, a lot of in-depth studies have been conducted to improve the performance of the drag-based vertical-axis wind turbine called Savonius rotor. This kind of vertical-axis wind turbine usually suffers from poor energy conversion efficiency, particularly for its conventional shape (thin half-cylinders). In the current work, a bionic blade shape of the Savonius-type wind turbine rotor inspired by sandeels (also called sandlances) is proposed, combined with an optimization step in order to maximize performance. Sandeels are slim elongated fish that often swim in vast shoals. The bionic blade is described by two principal geometrical parameters, both divided by the blade length (d); the maximum blade camber (fmax) and its location (Xfmax). The optimization relies on evolutionary algorithms to maximize the average power coefficient of the Savonius rotor with sandeel-inspired blades when varying the two design parameters. A total of 128 individuals have been evaluated numerically using a series of two-dimensional transient simulations with the software Star-CCM+. In comparison to the conventional rotor with two arc-type semi-circular blades, the optimal design with sandeel-inspired blades exhibits a considerable increase in turbine efficiency of up to 9.21% at the design tip speed ratio (λ = 0.8). Investigating the performance over the entire operating range results in a maximum power coefficient of 0.255 by the optimal rotor, leading to a gain of about 10.58% with respect to the standard rotor at λ=1.

The optimal design and research of interior permanent magnet synchronous motors for electric vehicle applications

AbstractAn interior permanent magnet synchronous motor (IPMSM) with “VV—” shape rotor topology structure is proposed, and its performances are compared with “V” shape and “V—” shape rotor topology structure. The results show that the performances including output average torque, reluctance torque, torque ripple, cogging torque, iron loss of the IPMSM with “VV—” shape is better than the other two rotors. Firstly, the parameters which have great influence on the torque and the efficiency of the IPMSM are analyzed and optimized. The no‐load back electromotive force (EMF) of three different optimized rotor topology structures are analyzed and compared, the results show that the no‐load back EMF of the IPMSM with “VV—” shape topology structure has the lowest total harmonic distortion rate (THD). Secondly, the torque of the IPMSM with “VV—” shape under different current angles, current densities and speeds are analyzed and compared with the other two rotors. The results show that the torque performance of the IPMSM with “VV—” shape rotor topology structure is better than that of the other two. Finally, aiming at the problems that the torque ripple and cogging torque of the IPMSM with “VV—” shape rotor topology structure are greatly increased when the iron loss is reduced, This paper proposes to add a set of circular flux isolation holes between the second layer and the third layer of permanent magnets, and the position and diameter of this set of circular flux isolation holes are optimized and adjusted. The results show that the torque ripple and cogging torque of the IPMSM with the further optimized “VV—” shape rotor topology structure are greatly reduced, and the THD of no‐load back EMF is also further reduced, which has great significance to reduce vibration and noise, improve the control accuracy of the IPMSM.