Internal Rotor Research Articles

Almost-Poisson Brackets for Nonholonomic Systems with Gyroscopic Terms and Hamiltonisation

We extend known constructions of almost-Poisson brackets and their gauge transformations to nonholonomic systems whose Lagrangian is not mechanical but possesses a gyroscopic term linear in the velocities. The new feature introduced by such a term is that the Legendre transformation is an affine, instead of linear, bundle isomorphism between the tangent and cotangent bundles of the configuration space and some care is needed in the development of the geometric formalism. At the end of the day, the affine nature of the Legendre transform is reflected in the affine dependence of the brackets that we construct on the momentum variables. Our study is motivated by a wide class of nonholonomic systems involving rigid bodies with internal rotors which are of interest in control. Our construction provides a natural geometric framework for the (known) Hamiltonisations of the gyrostatic generalisations of the Suslov and Chaplygin sphere problems.

Study on the effect of bearing position and stiffness on the dynamic behavior of output stage of CHT system based on the cylindrical gear meshing

The internal and external rotor shafts are important components to transfer power in coaxial helicopters, and bearing supports could affect the dynamic behavior of the transmission system. In order to explore the influence of bearing support structure, bearing position and support stiffness on the dynamic behavior of the output stage of coaxial helicopter transmission (CHT) system based on the cylindrical gear meshing, a rigid-flexible coupled dynamic model is established under cantilever-cantilever support structure and cantilever-simple support structure considering the flexibility of rotor shaft based on Timoshenko beam theory, and time-varying mesh stiffness (TVMS), comprehensive meshing error are also considered. Newmark-beta numerical method was applied to calculate the dynamic response. The result indicates that the load sharing performance of gear pair using cantilever-simple support structure is better than that of cantilever-cantilever structure, but the maximum vibration displacement of bull gears is reduced apparently. Simultaneously, the bearing positions and stiffness can be adjusted to achieve better performance in load distribution and maximum vibration displacement of bull gears.

Coupled internal rotations and 14N quadrupole hyperfine structure of 2,4-dimethylpyrrole investigated by microwave spectroscopy and quantum chemistry.

The microwave spectrum of 2,4-dimethylpyrrole was investigated using a Fourier-transform microwave spectrometer in a supersonic expansion. Torsional splittings arising from two inequivalent methyl internal rotors in combination with hyperfine splittings due to the nuclear quadrupole coupling of the 14N nucleus were observed. The experiments were accompanied by quantum chemical calculations. A total of 1561 rotational lines were assigned and fitted in global fits using the programs XIAM and BELGI-Cs-2Tops-hyperfine, both achieved the measurement accuracy of 4kHz. Local separate fits were also performed to verify the correctness of the assignment. Accurate experimental molecular and internal rotation parameters could be deduced and compared to the calculated ones. The barrier to internal rotation of the 2-methyl rotor was determined to be 277.830(26) cm-1, essentially the same as the value of about 280cm-1 found for 2-methylpyrrole but lower than the value of 317cm-1 found for 2,5-dimethylpyrrole. The torsional barrier value of the 4-methyl rotor is 262.210(27) cm-1, slightly higher than the value of 246cm-1 found for 3-methylpyrrole. Benchmarking the rotational constants for 2,4- and 2,5-dimethylpyrrole revealed that the MP2/6-31G(d,p) level could be helpful to guide the assignment of microwave spectra of pyrrole derivatives.

A global rho-axis method for fitting asymmetric tops with one methyl internal rotor and two 14N nuclei: Application of BELGI-2N to the microwave spectra of four methylimidazole isomers.

A number of internal rotation codes can deal with the combination of one or two internal rotors with one 14N quadrupole nucleus, but once it comes to two 14N nuclei, no such code is available even for the case of one internal rotor. We present here the extension of our internal rotor program called BELGI-2N using the rho-axis method global approach to deal with compounds containing one methyl rotor and two weakly coupling 14N nuclei. To test our new code, we applied it to the microwave data recorded for N-methylimidazole, 2-methylimidazole, 4-methylimidazole, and 5-methylimidazole using a chirped-pulse Fourier transform microwave spectrometer in the 7.0-18.5GHz frequency range. Compared to the previously published study, BELGI-2N was able to (i) significantly increase the number of assigned and fitted lines, (ii) fit the complete datasets considering both the internal rotation and the 14N nuclear quadrupole coupling effects simultaneously, and (iii) achieve standard deviations within the measurement accuracy for all methylimidazole isomers.

ПОРІВНЯЛЬНИЙ АНАЛІЗ МАЛОГАБАРИТНИХ ВИСОКОШВИДКІСНИХ СИНХРОННИХ МАГНІТОЕЛЕКТРИЧНИХ ДВИГУНІВ

Using the methods of mathematical modeling, a comparative analysis of the characteristics of three variants of small-sized high-speed synchronous magneto-electric motors (SMD) with permanent magnets on the rotor, which are intended for driving the propeller of quadcopter-type aircraft, was investigated and carried out. Namely: SMD with external grooved stator and internal rotor; SMD with internal grooved stator and external rotor; SMD with internal clear-pole stator and external rotor. On the example of an aircraft with a total mass of 4 kg, a comparative analysis of the amount of power developed by the specified engine variants under the same operating conditions: the same overall dimensions, rotor speed, current in the stator winding and volume of permanent magnets was carried out. An assessment of the magnitude of electromagnetic moment pul-sations is given. It was established that although an SMD with an internal clear-pole stator is the most technologically simple, but under the same other conditions, it is inferior in power to an SMD with an internal slotted stator and an external rotor. References 7, Figures 4.

Construction of the mathematical model of magnetic transmission for an autonomous wind power plant

The object of research is electromagnetic and mechanical processes in magnetic transmission for an autonomous wind power plant of small power. The use of magnetic transmission as part of an autonomous wind power plant makes it possible to improve the reliability and efficiency of such a system. In the current work, a study of magnetic transmission as part of an autonomous wind power plant was carried out to investigate the parameters and characteristics of magnetic transmission. This paper reports the construction of a numerical simulation mathematical model of a magnetic reducer operating as part of an autonomous wind power plant with a permanent magnet generator. The model takes into account discrete structure of internal and external rotors and modulator; changes in model parameters when input parameters change. It also takes into account losses, change of load angle and electromagnetic moment; the effect of changing the generator load. The built model of the magnetic reducer system differs in that the change in the generator load leads to a shift of the operating point on the mechanical characteristics of the rotor of the wind power plant (WPP). The model also works in the opposite direction: changes in wind parameters affect power, voltage, current, and electromagnetic moment. With the help of the model built, the parameters and characteristics of not only the magnetic reducer but also other components of the system were investigated. The efficiency at the output of the electric generator was determined, which is ≈75 % at a load of 2.0 kW. The magnetic transmission moment at a wind speed of 7.8 m/s for the high-speed rotor is 0.91 N∙m, and the low-speed rotor is 7.8 N∙m, which corresponds to a transmission ratio of 8.6. This expands opportunities for exploratory research

A novel rotor internal bend actuator for the wireless compensation of inherent eccentricities

A novel internal rotor bend actuator is presented that enables compensating strains to be applied about the rotor centre. Axial reaction tubes are used to maintain the structural stability of the bend actuator and to provide feedback on the level of actuation. The system is powered by an onboard battery and the actuation is derived from the operation of lead screw motors. The actuation is commanded wirelessly, thus providing the functionality for an autonomous rotor. The integrated rotor is demonstrated in isolation via laser tracker measurements and for the rotating prototype system. Actuated bending gave rise to radial displacements at the central point relative to shaft ends of approximately 50µm peak-to-peak. These results validate a finite element deformation model. The rotor was levitated on active magnetic bearings, then rolling elements bearings, to demonstrate the synchronous vibration control achievable by static internal bending. The potential now exists for the commanded actuation to compensate for rotor eccentricities arising from manufacturing errors and dynamically induced unbalance for the cancellation of underlying synchronous vibration.

Ammonia – Formic acid complex: internal rotation analysis, calculations, and new microwave measurements

New analysis and spectra are reported for the gas-phase ammonia-formic acid complex. Calculations to determine the theoretical barrier to internal rotation were conducted and led to the new internal rotation analysis of the dimer. Using the new analysis and calculations, 12 new lines were measured and assigned and included in the present analysis. This is the first internal rotation analysis for this complex. The measurements were made in the 7–22 GHz range using two Flygare-Balle type pulsed beam Fourier transform microwave (FTMW) spectrometers. The complex was analyzed as a hindered rotor and 20 A and 16 E state transitions were fit with the XIAM5 program. The rotational constants were determined to have the following values: A = 11970.19(9) MHz, B = 4331.479(4) MHz, and C = 3227.144(4) MHz. Rotational constants, quadrupole coupling constants, and internal rotor parameters were fit to the spectrum. Double resonance was used to verify line assignments and access higher frequencies. The barrier to internal rotation was found to be 195.18(7) cm−1. High level calculations are in good agreement with experimental values. The calculated V3 barrier values range from 168.3 to 212.8 cm−1.

Fast‐Moving and Highly Adaptable Hollow Piezoelectric Miniature Robot

Fast motion and high adaptability are crucial for the practical applications of miniature robots. However, combining these capabilities into a single robot skillfully is challenging, particularly in the domain of miniature structural design. Inspired by the amphibious motion of crocodiles in nature, a hollow piezoelectric miniature robot (HPMR) is proposed. The key benefit of the HPMR is to concurrently output the oscillating motion of the driving foot (oscillating mode) and the rotating motion of the internal rotor (rotating mode). That is, the mode of single‐energy‐input‐multimotion output allows the robot to balance the requirements of speed and adaptability. In the oscillating mode, HPMR can run at speeds of up to 12.3 BL s−1 and realize a displacement resolution of 0.3 μm. Following the conical rotor assembly, the rotor can operate at a speed of 890 rpm, with a displacement resolution of 7.28 mrad. In the rotating mode, the robot demonstrates its multitasking ability in moving amphibiously, carrying loads, running on surfaces with varying roughness, crossing obstacles, and resisting shocks. The results show that the HPMR is capable of fast, high‐resolution moving combined with high adaptability, opening up the possibility of using it for mobile detection tasks in real‐world settings.

Axial Flux Permanent Magnet Motor Topologies Magnetic Performance Comparison

Axial flux permanent magnet motors have attracted increasing attention due to their compact topology and high torque density. Many topological variations have arisen over time; however, limited research has directly compared the differences in magnetic performance of these topologies. This paper carries out a comprehensive investigation, employing both analytical and 3D finite element analyses, to compare the magnetic performance of three topologies: yokeless and segmented armature (YASA), axial flux internal rotor (AFIR), and offset AFIR. The findings reveal that each topology offers specific advantages for different applications. The YASA topology excels in minimizing core losses; the AFIR configuration achieves the highest torque density; and the offset AFIR topology shows the highest efficiency. The offset AFIR topology appears to offer advantages for a wide array of applications due to its higher power factor and lower permanent magnet loss, leading to reduced costs for converter design and cooling system design.

Attitude dynamics of a dual-spin nanosatellite with a gravitational damper

The paper considers a process of a controlled attitude motion of a dual-spin nanosatellite. The main goal of control is to achieve a gravitationally stabilized position in a circular orbit in the shortest possible time. The dual-spin nanosatellite contains a gravitational damper and an internal rotor inside a movable unit. The movable unit can fulfill small controlled inclination relative to the main body of the nanosatellite. The mathematical model of the attitude dynamics of the nanosatellite is built and appropriate control laws are developed. Simulation results confirm the performance of the gravitational damper and efficiency of the control algorithm.

Attitude optimization by extremum seeking for rigid bodies actuated by internal rotors only

SummaryIn this paper, we investigate the stabilizing effect of an extremum seeking control law on a class of underactuated Lagrangian control systems with symmetry. Our study is motivated by the problem of attitude optimization for satellites with reaction wheels. The goal is to minimize the value of an analytically unknown configuration‐dependent objective function without being reliant on measurements of the current configuration and velocity. This work extends our previous work on extremum seeking control for fully actuated mechanical systems on Lie groups in the absence of dissipation. We show that the earlier method for fully actuated systems can also be successfully applied to a certain class of underactuated systems, which are controlled by internal momentum exchange devices (reaction wheels) so that the total momentum is conserved. Conservation of momentum allows us to reduce the control system to a system on a smaller state manifold. The reduced control system is not of Lagrangian form but fully actuated. For the reduced control system we prove that the extremum seeking method leads to practical uniform asymptotic stability. We illustrate our findings by the example of a rigid body with internal rotors.

The influence of blade fracture on the internal flow characteristics and rotor system of horizontal centrifugal pumps

The blade fracture of horizontal centrifugal pump will not only affect the hydraulic performance of the pump, but also affect the safety and stability of the whole unit. In this paper, for horizontal centrifugal pumps, five single-blade fracture schemes are designed and numerical simulations are carried out under different operating conditions. The results show that with the increase of fracture size, the influence on the hydraulic characteristics of the pump shows a decreasing trend, and it will also affect the turbulent kinetic energy distribution near the impeller inlet, so that the internal flow becomes complex and the flow loss increases. The radial force on the impeller changes periodically, and its magnitude shows a nonlinear decreasing change with the increase of the fracture size. The pressure pulsation analysis of several monitoring points in the worm shell shows that as the fracture size increases, the amplitude of the lobe frequency slowly rises, and the shaft frequency, which is second only to the lobe frequency, becomes higher and higher and begins to dominate. A study of the rotor system shows that the maximum deformation of the impeller occurs at the edge of the impeller cover and the maximum equivalent stress occurs at the blade exit; blade fracture causes a significant reduction in the latter third-order intrinsic frequency.

ТРИСТУПЕНЕВА ЕЛЕКТРИЧНА МАШИНА З ВНУТРІШНІМ ТА ЗОВНІШНІМ РОТОРОМ: ПОРІВНЯЛЬНИЙ АНАЛІЗ ПОКАЗНИКІВ КЕРОВАНОСТІ

Two structures of electric machines with three degrees of freedom of the rotational movement of the rotor are considered - with an external and an internal rotor held on an internal cardan suspension. A three-plane symmetric magnetic system was chosen for the comparative analysis and such a choice was justified. Limitations are formulated that allow considering the rotor as a conservative mechanical system, as well as considering the magnetic field in the electric machine as magnetostatic. Mathematical models of the rotational motion of a body with a fixed center of mass, as well as the force interaction of the magnetic field of a permanent magnet located on the rotor and the control winding located on the stator, are given. The peculiarities of the distribution of electromagnetic forces in both structures are analyzed and the greater efficiency of the formation of these forces in the structure with an internal rotor is shown. Expressions for the components of the electromagnetic moment for use in the "COMSOL Multiphysics" interface are obtained. Forced precession movement for both structures was analyzed in the case of equal radii of the control windings and in the case of the same dimensions of the magnetic systems. It was determined that the structure with an external magnetic circuit is able to provide an order of magnitude smaller angular velocity of precessional movement and, at the same time, an equally smaller range of nutation. References 14, figures 10.

A Theoretical Study of NH2 Radical Reactions with Propane and Its Kinetic Implications in NH3-Propane Blends’ Oxidation

The reaction of NH2 radicals with C3H8 is crucial for understanding the combustion behavior of NH3/C3H8 blends. In this study, we investigated the temperature dependence of the rate coefficients for the hydrogen abstraction reactions of C3H8 by NH2 radicals using high-level theoretical approaches. The potential energy surface was constructed at the CCSD(T)/cc-pV(T, Q)//M06-2X/aug-cc-pVTZ level of theory, and the rate coefficients were computed using conventional transition state theory, incorporating the corrections for quantum tunneling and hindered internal rotors (HIR). The computed rate coefficients showed a strong curvature in the Arrhenius behavior, capturing the experimental literature data well at low temperatures. However, at T > 1500 K, the theory severely overpredicted the experimental data. The available theoretical studies did not align with the experiment at high temperatures, and the possible reasons for this discrepancy are discussed. At 300 K, the reaction of NH2 with C3H8 predominantly occurs at the secondary C-H site, which accounts for approximately 95% of the total reaction flux. However, the hydrogen abstraction reaction at the primary C-H site becomes the dominant reaction above 1700 K. A composite kinetic model was built, which incorporated the computed rate coefficients for NH2 + C3H8 reactions. The importance of NH2 + C3H8 reactions in predicting the combustion behavior of NH3/C3H8 blends was demonstrated by kinetic modeling.

Use of positron emission particle tracking to assess mixing of a graphite-based lithium-ion anode slurry in an Eirich mixer

The mixing of electrode slurries is a key processing step during the manufacturing of lithium-ion batteries, and poor mixing can have a profound effect on final cell electrochemical performance. This is complicated by the evolving non-Newtonian rheology of these slurries. In this study, Positron Emission Particle Tracking (PEPT) is used to determine the fluid dynamics and dispersion of a model graphite-based anode slurry in an Eirich EL1 mixer, equipped with a rotating pan, wall scraper and internal rotor. The main processes studied are the wetting of graphite particles and breakup of large graphite agglomerates. For experiments performed at different internal rotor tip speeds, with fixed outer pan speed, the dispersion dynamics change with the lowest rotor speed (2 m/s) leaving a large channel of poor mixing between the rotor region and the rotating pan, whilst the mixing within the vessel is mainly driven by the rotating pan. At higher mixing speeds (6 and 10 m/s) more of the vessel volume is active and there is no longer a poor mixing region observed, with 10 m/s tip speed producing the highest intensity of dispersion. An increasing mixer effectiveness (average dispersion across the mixing vessel) as well as an increasing dispersion co-efficient (rate of mixing) is also observed, which will be use to inform scale-up criteria.

Assessment of Bach-type internal rotor on the performance of a hybrid wind turbine: effects of attachment angle, tip speed ratio, and free-wind speed

ABSTRACT The application of the Darrieus rotors in regions with lower wind potentials is one of the challenging issues in the operation of this type of vertical axis wind turbine (VAWT). To overcome this problem, various combinations of Darrieus and Savonius rotors, called the hybrid rotor, are proposed, which is one of the attractive subjects among wind turbine researchers. Using the computational fluid dynamics technique (CFD), this study investigates a new combination between the Savonius and Darrieus rotors at which a two-bladed Bach-type rotor is attached inside a two-bladed Darrieus rotor made by NACA 0018. In this way, various attachment angles (α) between the internal and external rotors such as 0°, 45°, and 90° are studied to find the optimal case. Computations are performed for various tip speed ratios (TSR) such as 1.5, 2.5, and 3.5, and free-wind speeds (U∞) of 5 and 10 m/s. The obtained results revealed that the application of a hybrid wind turbine is more beneficial under lower TSR and U∞ values. Additionally, it is demonstrated that the case with α = 90° is the optimal case in TSR = 1.5 and 2.5 providing a maximum 21.43% improvement in comparison to the Darrieus rotor for TSR = 1.5 and U∞ = 5 m/s.

Novel Pumping System based on Micro-Hydro Turbine and Centrifugal Pump coupled using EVT Induction Machine. Application in Rural Area Irrigation

In this article, a topology for energy conversion oriented to water pumping for irrigation in remote areas is proposed. A micro-hydraulic turbine working at fixed speed, in a "run-off-river" configuration, drives a centrifugal pump through a variable electric transmission (EVT). An EVT based on induction machines was selected, with the stator directly connected to a weak AC grid but the internal rotor fed by a variable frequency drive, allowing an adjustable pump speed. The grid supplies a base power for residential consumption, while the hydro turbine increases the available power for irrigation and thus augmenting productivity of the land uphill and beyond the vicinity of the watercourse. The grid also provides an assistance function, absorbing/delivering a reduced amount of power in case the hydraulic resource is excessive/insufficient for the requested water pumping. As the turbine delivery is constant, the water pumping requirement establishes the power exchanged between turbine, AC grid and pump. For this reason, an analysis to quantify the power flow in the system components for different pump speeds has been carried out. The system modeling is described and computer simulations, using a specific pump speed profile, are presented to validate the performed theoretical analysis.

Design Methodology of a Multifunctional Screw-Type Energy Converter

This paper examines the method of designing a non-standard electric machine – a three-phase induction motor with a hollow solid rotor, on the surface of which the turns of the screw are located. Such an unusual design makes it possible to turn the main disadvantage of induction machines with a solid rotor, namely the heating of the rotor due to the effect of eddy currents, into an advantage. The heat from the rotor is transferred to the bulk material, which is mixed by the screw, for drying and reducing the moisture content. At the same time, only one device is used to perform three functions - mixing, drying, transportation of bulk material, which, due to the specified functional features, was called a multifunctional energy converter (MEC). The MFEC design method differs from conventional machines, because it takes into account the peculiarities of determining the parameters of a number of typical methods: an induction motor with a squirrel-cage rotor, an induction motor with a solid internal rotor, and an inductor. In the previous publications of the authors, the complex methodology of designing an induction motor with an external solid rotor was considered in detail, however, in view of the additional theoretical and experimental studies conducted, it needs to be clarified and adjusted. In addition, in this paper, the beginning of the design, the determination of the initial data and the main dimensions of the MFEC is performed in a different way. In particular, the overall dimensions of the MFEC are determined not by the sum of power spent on heating and mixing the material and internal losses in an induction machine (considering the efficiency and power factor), but by the required performance of the unit and the limit dimensions of the installation area. The paper proposes a new approach to determining the dimensions of the stator slot, considering the necessary area for the placement of conductors and the current density in the winding. This paper is one of several publications that aim to reveal the features of design and mathematical modeling of such an atypical class of electric machines as an induction motor with an external hollow solid rotor.

Broadband and Multi-Cylinder-Based Triboelectric Nanogenerators for Mechanical Energy Harvesting with High Space Utilization.

The development and utilization of new energy sources is an effective means of addressing the limits of traditional fossil energy resources and the problem of environmental pollution. Triboelectric nanogenerators (TENG) show great potential for applications in harvesting low-frequency mechanical energy from the environment. Here, we propose a multi-cylinder-based triboelectric nanogenerator (MC-TENG) with broadband and high space utilization for harvesting mechanical energy from the environment. The structure consisted of two TENG units (TENG I and TENG II) assembled by a central shaft. Both an internal rotor and an external stator were included in each TENG unit, operating in oscillating and freestanding layer mode. On one hand, the resonant frequencies of the masses in the two TENG units were different at the maximum angle of oscillation, allowing for energy harvesting in a broadband range (2.25-4 Hz). On the other hand, the internal space of TENG II was fully utilized, and the maximum peak power of the two TENG units connected in parallel reached 23.55 mW. In contrast, the peak power density reached 31.23 Wm-3, significantly higher than that of a single TENG unit. In the demonstration, the MC-TENG could power 1000 LEDs, a thermometer/hygrometer, and a calculator continuously. Therefore, the MC-TENG will have excellent application in the field of blue energy harvesting in the future.