Search Results (29)

The course of altering “wind flow energy” into mechanical energy by means of two counter-rotating wind helms is considered in this article. Mechanical energy is then transformed into electrical energy in a generator where the carcase and the inductance switch are in reverse order. This counter-rotation principle increases the relative speed between the magnetic field and the armature, thereby improving the overall efficiency of energy conversion. The key purpose of this investigation is to advance an effective power source system for independent customers grounded on a specifically planned wind power enterprise with an improved wind energy use constant. The emphasis of the paper is to fix the best strategy parameters of the wind turbine by performing mathematical modelling of the electricity generation process based on the counter-rotation principle and the developed physical prototype. In order to evaluate the key performance parameters for efficient power supply to autonomous consumers, agriculture experimental studies were conducted on the prototype. The key project and techno-economic dials comprised the optimisation of wind power enterprise data, wind helm extents, their comparative placement, and producer control production as purposes of the predictable wind rapidity. The practical implementation of the proposed design was demonstrated by patents granted for a wind generator with variable rotor torque (Patent of the Republic of Kazakhstan No. 36903; Eurasian Patent No. 047230). The results demonstrated that the developed wind turbine achieved higher energy efficiency compared to the conventional single-rotor systems. Thus, the proposed design is suitable for applications in alternative energy and decentralised power supply for remote agrarian customers. Full article

This paper addresses the torque generated in a six-phase permanent-magnet synchronous machine (6PMSM) when it is reused as a three-phase integrated on-board battery charger in electric vehicles. The inequality stator-phase disposition produces unequal equivalent inductances among the windings, which unavoidably creates electromagnetic torque. A novel six-phase open-end winding topology is first introduced: during charging, both sides of every open-winding act as grid-side harmonic filters; under ideal balanced conditions, the two halves carry currents that are equal in magnitude and opposite in direction, so the counter-rotating fields cancel and no net torque is produced. However, this perfect condition is difficult to achieve in the real system in practice. More than a 5% difference (inequality) in stator winding inductance can be observed at different rotor positions. Consequently, a dedicated current-control strategy is developed in order to compensate the unequal inductance, force the winding currents back into balance, and thereby eliminate the undesired torque while providing additional harmonic attenuation. In the proposed charging mode, the system operates at 0.99 power factor with zero average torque and a total grid current harmonic distortion (THD) of 3.47%. Experimental results verify that the proposed topology and control algorithm successfully keep the 6PMSM torque-free even when the machine is operated as grid filter inductance. Full article

This study investigates whether aerodynamic interaction effects in an interlocked (negative-gap) counter-rotating dual Savonius rotor configuration can improve the efficiency of drag-based vertical-axis wind turbines in urban wind conditions. Two-dimensional Computational Fluid Dynamics (CFD) simulations were performed in ANSYS Fluent 2025 R2 using both steady and unsteady RANS approaches, including dynamic meshing to enable collision-free rotation in the interlocked overlap region. The numerical setup was first validated for a single two-bucket reference rotor against published experimental data of torque and power coefficients and subsequently applied to dual-rotor configurations with negative gap distances. The results show that the dual-rotor arrangement redistributes torque production over the azimuth angle and yields a smoother and consistently positive mean static torque coefficient, indicating improved self-starting behavior compared to the single rotor. Under transient operation, the dual-rotor configuration yields higher power coefficient values across the entire investigated tip-speed ratio range. The highest performance gain is observed at a tip-speed ratio of $\lambda \approx 1.0$, where the peak power coefficient increases from $c_p\approx 0.25$ (single-rotor) to $c_p\approx 0.32$ (dual-rotor), corresponding to an improvement of the power coefficient of about $\mathsf{\Delta }{c}_p/c_{p0}\approx 28\%$. Full article

Micro-scale counter-rotating wind turbines (CRWTs) offer enhanced potential for wake energy recovery. This study proposes an integrated cascade–coupling design framework for high-solidity CRWTs, in which rear rotor geometry and rotor coupling are co-designed based on stereoscopic particle image velocimetry measurements of the front rotor wake. Experiments are conducted at a tip-speed ratio of $\lambda =1.0$, solidity $\sigma =1.25$, spacing ratios of $d=0.6R_T$, $1.0R_T$, and $3.0R_T$, and a tip radius of $R_T=70$ mm. At the physical limit spacing of $d=0.6R_T$, the integrated design increases the system power coefficient by 24.1% while limiting front rotor power reduction to 17.2%, compared to a 10.3% system gain and 34.5% front rotor suppression for the baseline mirrored configuration. Wake measurements confirm near-complete absorption of rotational kinetic energy from the front rotor wake without exacerbating upstream interference. These results demonstrate that cascade-based energy extraction and coupling-based interference mitigation can operate synergistically, enabling compact, high-performance micro-scale CRWTs suitable for space-constrained and urban energy applications. Full article

As with wind turbines, marine tidal turbines are expected to be deployed in arrays of multiple turbines. To optimize these arrays, a more profound understanding of the interactions between turbines is necessary. This paper employs the Actuator Line Method alongside the Lattice Boltzmann Method and Large Eddy Simulation to develop a numerical model of tidal turbine arrays. It studies a vertical-axis turbine manufactured by HydroQuest/CMN that is equipped with two counter-rotating columns, each comprising two rotors. The ambient turbulence and upstream velocity profiles correspond to the characteristics of a tidal site such as the Alderney Race. Six turbine layouts are modeled: three aligned layouts with three turbines and three staggered layouts with four turbines. The spacing between turbines varies depending on the layout. This study yields several observations regarding array configuration. A minimum distance of 300 m, or $12D_{eq}$, between aligned turbines is necessary for full wake recovery. At shorter distances, the accumulation of velocity deficits significantly decreases the efficiency of the third turbine in the array. Pairs of counter-rotating vortices are observed in the wake of turbines. The evolution of these vortices and their influence on the wake depend greatly on the array configuration. An optimal configuration is observed in which the overall averaged power is not impaired by the interactions. Full article

In this paper, the performance of the Independent Dual Rotor Wound Field Flux Switching Generator (IDRWFFSG) under locked rotor fault scenarios and counter-rotating operational direction for fault withstand capability is investigated. The IDRWFFSG and the locked rotor fault scenarios are defined, and the magnetic path formation is explained. An integrated mathematical and electromagnetic modelling of the generator characteristics performance comprising torque quality, output power, efficiency and power factor are undertaken, based on the finite element method (FEM) under fault conditions. The electromagnetic characteristics are investigated independently for the inner and outer rotors under locked conditions while the counterpart rotor is rotated in both clockwise (CW) and counterclockwise (CCW) directions. The analysis confirms that CCW offers a comparatively better response than CW, with excellent locked rotor fault withstand capability. In the case of CCW operation, the average torque, output power, efficiency, and power factor are improved. Based on the results, it is determined that the rotational direction of the rotor is selected depending on the prerequisite demand of high efficiency, high power factor, and high output power when one of the rotors goes under a locked condition. Finally, a test prototype is developed to validate the predicted electromagnetic characteristics, of which the measured results confirm the effectiveness of the IDRWFFSG fault withstand capability study. Full article

The paper addresses the dynamic modeling and numerical simulation of a novel single-rotor wind system with a planetary speed increaser and counter-rotating direct current (DC) generator, patented by authors, during the transient stage from rest. The proposed analytical dynamic algorithm involves the decomposition of the wind system into its component rigid bodies, followed by the description of their dynamic equations using the Newton–Euler method. The linear mechanical characteristics of the DC generator and wind rotor are added to these dynamic equations. These equations allow for the establishment of the close-form equation of motion of the wind system and, implicitly, the time variation of the mechanical power parameters. Numerical simulations of the obtained analytical dynamic model were performed in MATLAB-Simulink in start-up mode from rest for the case study of a 100 kW wind turbine. These results allowed highlighting the time variation of angular velocities and accelerations, torques, and powers for all system shafts, both in the transient regime and steady-state. The implementation, in this case, of the counter-rotating generator indicates a 6.4% contribution of the mobile stator to the generator’s total power. The paper’s results are useful in the design, virtual prototyping, and optimization processes of modern wind energy conversion systems. Full article

Vertical-axis wind turbines (VAWTs) are receiving more and more attention as they involve simple design, cope better with turbulence, and are insensitive to wind direction, which has a huge impact on their cost since a yaw mechanism is not needed. However, VAWTs still suffer from low conversion efficiency. As a result, tremendous efforts are being exerted to improve their efficiency, which mainly focus on two methods, regardless of whether the study is a CFD simulation, a field test, or a lab test experiment. An active approach involves modification of the rotor itself, such as the blade design, the angle, the trailing and leading edges, the inner blades, the chord thickness, the contra-rotating rotor, etc., while the second approach involves passive techniques where the flow is directed to optimally face the downwind rotor by mounting guiding vanes such as a diffuser or other shapes at the upwind position of the rotor. Among all the techniques undertaken, the counter-rotating wind turbine (CRWT) rotor technique seems to be the most effective, with an output comparable to that of horizontal-axis wind turbines (HAWTs), while the Savonius rotor has received more attention compared to other VAWT designs. Apart from technological issues, it has also been suggested that geographical issues, such as proper site siting of a wind turbine rotor at a particular location where a uniform flow can be guaranteed, are of paramount importance to ensure an effective conversion capacity of wind turbines. Thus, this study has successfully highlighted the latest improvements in augmentation methods and has established a solid foundation for future research aimed at improving the efficiency of VAWTs. Full article

In this study, the focus is on the magnetic path formation and its effects on the performance of a counter-rotating dual-rotor permanent-magnet flux-switching machine (CR-DRPMFSM) for direct-drive counter-rotating wind power generation, based on different stator slot and rotor pole combinations. To fully exploit rotor-shaft bore and improve fault-tolerant design, as well as increase torque density, dual-rotor topologies with the capability for dual electrical and dual mechanical ports are investigated. Moreover, the direct-drive counter-rotating wind power generation technique offers a brushless topology, thus reducing maintenance cost and improving energy conversion efficiency compared to single-blade wind turbine systems. Using finite element analysis (FEA), the inherent magnetic coupling of the series and parallel paths shows varied impacts on the electromagnetic performance of four different CR-DRPMFSMs based on the slot/pole combinations (MI to MIV) considered in this study. The key electromagnetic performance indices, such as torque, cogging torque, torque ripple, power factor, and efficiency, show proportionate variation to the coupling level. A comparative analysis shows that MI exhibits higher average torque, lower torque ripples, and high efficiency, reaching 90% with a power factor of 0.6. As an optimal design, an MI test prototype is developed. The experimental test prototype validates the FEA results under no-load and on-load conditions. Full article

Nowadays, there are numerous new features available in CFD (computational fluid dynamics) that can simulate complex physical phenomena, which used to be challenging to address. However, in current CFD software, certain problems can be simulated using different approaches. In our article, we chose different rotating motion methods to analyze a counter-rotating dual-rotor wind turbine (CO-DRWT). Using the different rotating motion approaches we selected (mixing plane, frozen rotor, and sliding mesh), we examined the torque on the rotors and compared them. The following conclusion was reached. If transient fluid flow must be examined, then the sliding mesh method provided the most realistic results, while the frozen rotor method was adequate if we investigated the effect of wake and vortex near the rotating blades or on its environment. The mixing plane method should be used when the focus is on the kinetics and kinematics of the rotating blade or structure. Full article

In this paper, dual-rotor counter-rotating (CR) configurations of vertical axis wind turbines (VAWTs) are briefly inspected and divided into three types. This investigation was focused on one of these types—the CR-VAWT with co-axial rotors, in which two equal rotors are placed on the same shaft, displaced from each other along it and rotated in opposite directions. For this CR-VAWT with three-blade H-Darrieus rotors, the properties of the design in terms of aerodynamics, mechanical transmission and electric generator, as well as control system, are analyzed. A new direct-driven dual-rotor permanent magnet synchronous generator was proposed, in which two built-in low-power PM electric machines have been added. They perform two functions—starting-up and overclocking of the rotors to the angular velocity at which the lifting force of the blades is generated, and stabilizing the CR-VAWT work as wind gusts act on the two rotors. Detailed in this paper is the evaluation of the aerodynamic performance of the CR-VAWT via 3D computational fluid dynamics simulations. The evaluation was conducted using the CONVERGE CFD software with the inclusion of the actuator line model for the rotor aerodynamics, which significantly reduces the computational effort. Obtained results show that both rotors, while they rotate in opposite directions, had a positive impact on each other. At the optimal distance between the rotors of 0.3 from a rotor height, the power coefficients of the upper and lower rotors in the CR-VAWT increased, respectively, by 5.5% and 13.3% simultaneously with some increase in their optimal tip-speed ratio compared to the single-rotor VAWT. Full article

Improving power output and reducing costs are crucial to the sustainable development of offshore wind power. In the present study, a dual-rotor wind turbine (DRWT) is proposed to improve wind energy capture efficiency by adding an auxiliary rotor behind the main rotor. The two rotors can be the same size or different sizes. This will result in different aerodynamic characteristics for DRWTs. In this paper, the NREL Offshore Baseline-5 MW and the NREL 750 kW single-rotor wind turbines (SRWTs) are used to configure three different types of DRWTs. The power output and wake characteristics of three different DRWTs with co-rotating (CO-DRWT) and counter-rotating (CR-DRWT) configurations on an actual scale are compared. The Reynolds-averaged Navier–Stokes (RANS) model with k-ω SST (shear stress transport model) is used to simulate the unsteady flow generated by the DRWT’s rotation. The present numerical results show that the power coefficient of the 5 MW-5 MW CO-DRWT can reach 1.22 times that of the 5 MW SRWT. Moreover, a faster wake velocity deficit recovery is found in the 5 MW-5 MW DRWTs because the high-velocity flow caused by the merging and mixing of the trailing vortices of the 5 MW-5 MW DRWTs brings an energy supplement to the wake velocity deficit. Full article

Wind turbine wake redirection drawn by a yaw control has been proposed as a strategy to improve the performance of wind farms. However, the characteristics and the development of the curled wake structure deformed by the yaw action of the rotor are not well understood. In the present study, the structure of the wake behind a wind turbine imparted with various yaw angles subjected to uniform inflow was investigated using large-eddy simulation. The NREL 5MW reference wind turbine was modeled with an actuator disk with rotation to study the deformation process of the curled wake. The source of the vertical asymmetry in the wake deformation was found to be based on the interaction of global wake rotation and a counter-rotating vortex pair induced by the yaw angle. The yaw angle had a profound influence on the distortion of the wake and its trajectory, whose effect was naturally mitigated with downstream distance. Full article

Wind energy conversion systems play a major role in the transition to carbon-neutral power systems, and obviously, a special attention is paid in identifying the most effective solutions for a higher valorization of the local wind potential. In this context, this paper presents a comparative study on the energy performances of wind turbines (WTs) that include a counter-rotating electric generator. Starting from an innovative concept proposed by the authors for a reconfigurable wind turbine with three clutches, four cases of WTs with counter-rotating generators are studied: a system with three wind rotors (WRs) and a 2-DOF (degrees of freedom) planetary speed increaser (Case A), with two counter-rotating WRs and a 1-DOF (Case B) or a 2-DOF (Case C) speed increaser and a 1-DOF single rotor wind system (Case D). An analytical archetype model for angular speeds, torques, powers and efficiency of the reconfigurable planetary speed increaser, corresponding to the general case with three inputs (Case A), was firstly derived. The analytical models of the other three cases (B, C and D) were results by customizations of the archetype model according to the kinematic- and static-specific effects of engaging/disengaging the clutches. The simulation of the analytical models for a numerical representative example with two variable parameters (input speed ratio $k_{\mathsf{\omega }}$ and input torque ratio $k_t$) allows highlighting the influence of various parameters (number of WRs, speed increaser DOF, $k_{\mathsf{\omega }}$ and $k_t$) on the input powers, power that flows through the planetary transmission and mechanical power supplied to the electric generator, as well as on the transmission efficiency. The obtained results show that the output power increases with the increase of the number of wind rotors, the transmission efficiency is the maximum for $k_t=1$ and the speed amplification ratio increases with the ratio $k_{\mathsf{\omega }}$. Full article

Magnetic gear mechanisms have advanced to have a promising future in transmission technology. Previous research indicates that magnetic gear mechanisms might replace mechanical gear mechanisms in some applications. Small-scale wind turbines (SWT) with counter-rotating rotors that were initially fitted by bevel gears are proposed to be replaced by a coaxial magnetic gear train (CMGT). The CMGT is intended for use as a speed multiplier in order to obtain maximum power at low wind speeds, due to its beneficial transmission of power without physical contact. The primary objective of this study is to build a dual-input CMGT that will be employed in the transmission system of small-scale counter-rotating wind turbines. A dual-input CMGT is built through the analytical modeling of an equivalent magnetic circuit (EMC), which aims to predict the magnetic flux density in the air-gaps of CMGT. Several models within design constraints were compared to obtain the optimum design parameters of the preliminary CMGT design resulting from an EMC analysis. The optimized critical design parameters were then selected and analyzed using finite-element analysis (FEA) to depict the performance of the proposed SWT design. According to the findings, the developed design can generate an inner air-gap flux density of 0.8314 T and an outer air-gap flux density of 1.0200 T. The model likewise produces promising simulation results with an output transmitted torque in the inner rotor (output link) of 8.7 Nm, 56.9 Nm in the outer rotor, and 48.0 Nm in the carrier with pole-pieces. Thus, this design can generate higher torque than a bevel-geared wind turbine. The speed characteristics are also compromised in order to raise the generator’s rotating speed to generate more power. Finally, this study demonstrates the performance and embodiment design of the proposed SWT using CMGT. Full article