Rotation Of Rotor Research Articles

Rolling and whip phenomenon of hollow rotor slipping on internal stator

Dynamic features of a rotor that rolls without or with whipping and slipping of own inner surface on a rigid stator are discussed. Change in the whirling direction associated with the rolling of the rotor from backward to forward was confirmed experimentally, i.e. in the case of an internal type for the stator-limiter in the direction of rotor rotation. Identification of dynamic behavior is made on the basis of eigenfrequencies and eigenmodes, motion orbits of an eccentric point (on the rotor), Campbell diagrams and AFC. The calculation of such characteristics has done using an original mathematical approach developed by the author earlier in order to describe the backward motion of common rotor on an external stator. A good agreement is obtained between the theoretical frequencies and amplitudes of vibration and the experimental ones. Therefore, the author’s technique is also suitable for the revealed forward rotor motion around the internal stator.

Evaluation of the rotor eccentricity added radial force of oscillating water column

Oscillating water column is a commonly used device for ocean wave energy utilization. Its axial-flow rotor with cantilever blades will be affected by additional radial force because of rotor eccentricity. In this study, eccentric and non-eccentric cases of an oscillating water column are comparatively studied to evaluate this additional radial force characters. Computational fluid dynamics simulations are conducted with experimental data verification. Results show that rotor eccentricity will not obviously influence the efficiency but will generate strong extra radial force. The dominant frequency of radial force becomes rotor rotation frequency and stator interference frequency instead of the rotor blade passing frequency in the non-eccentric case. This is because of the non-uniform distribution of pressure in the uneven tip leakage when rotor becomes eccentric. The evaluation of the amplitude, frequency and generating mechanism of the rotor eccentricity added radial force will be helpful for oscillating water column in avoiding potential accidents.

Dynamic modeling and simulation analysis of inter-shaft bearing fault of a dual-rotor system

In order to study the vibration characteristics of inter-shaft bearing failures of a dual-rotor system, an eight-degree-of-freedom dynamic model of dual-rotor system containing inter-shaft bearings is established. The Newmark-β method is used to solve the proposed model equations. The dynamic characteristics of the rotor system when the inner ring and outer ring of the inter-shaft bearing has single-point failures or composite failures are analyzed. The comparison results show that the fault frequency distribution pattern in the envelope spectrum of the dynamic simulation results is consistent with that of the test results, which proves the effectiveness of the proposed dynamic model. It is found that when the inter-shaft bearing fails, a combination of rotor rotation frequency, multi-frequency, and fault frequency modulation frequency occurs in the fault characteristic frequency of the dual-rotor system. In addition to the speed-synchronized vibration components caused by the eccentricity, the rotor vibration signal is usually accompanied by a high-order harmonic vibration signal.

Theoretical study on the aggregation‐induced emission mechanism of anthryl‐tetraphenylethene

AbstractSince the concept of aggregation‐induced emission (AIE) was proposed by Benzhong Tang's research group in 2001, the exploration of the mechanism of AIE and the development of new high‐performance AIE materials have been the focus and goal of this field. On the basis of a large number of experiment results, AIE mechanism has been well explained by lots of works, such as restricted intramolecular motion (RIM), J‐aggregate et al. As tetraphenylethlene (TPE) molecules are stacked, the rotation of the benzene ring rotor is blocked, and the energy attenuation is released in the form of radiation, showing the AIE effect. In order to further explore the AIE effect of TPE, we performed electronic structure, spectrum simulation, and AIE mechanism calculations of the anthryl‐tetraphenylethene (TPE‐an) monomer and dimer in the gas phase, tetrahydrofuran (THF), and aqueous solutions at the B3LYP/6‐31G** level. The calculation results show that TPE‐an molecule is in a propeller‐like configuration, and its fluorescence intensity is weak; compared with the monomer, the fluorescence intensity of the dimer increases by 87% in aqueous solution; the fluorescence intensity in the gas phase, THF solution, and aqueous solution gradually enhances with the increase of the degree of aggregation, which are consistent with the experimental results. The enhancement of fluorescence intensity is caused by the change of molecular structure caused by aggregation. This detailed AIE luminescence mechanism will provide theoretical guidance for AIE material design.

The effects of swirling purge leakage on aerothermal performance of flat and non-axisymmetric endwalls

The relative rotation of turbine rotor determines the velocity triangle of the purge flow, which significantly influences the aerothermal performance of turbine endwalls. In this paper, a turbine cascade model is constructed to simulate the relative motion effect between the rotor endwall and the purge leakage. The effects of the swirl ratio of the purge leakage on the aerothermal performance of two endwall schemes (flat endwall and non-axisymmetric endwall) are investigated and compared. The results show that due to the relative motion, the purge leakage's flow direction and migration trajectory shift towards the blade suction side. The cooling jets tend to push the boundary layer towards the suction side, thus enhancing the lateral secondary flows. At a low MFR, with the decrease of swirl ratio, both endwalls' film cooling effectiveness is gradually reduced, with the aerodynamic performance and heat transfer coefficient changing very little. At a high MFR, with the decrease of swirl ratio, the aerodynamic loss and heat transfer coefficient of both endwalls are gradually increased, while the endwall film cooling effectiveness is gradually decreased. Globally, compared to the flat endwall, the non-axisymmetric endwall can dramatically enhance the film cooling effectiveness while effectively reducing the aerodynamic loss and heat transfer levels for all swirl ratios and MFRs investigated.

Effect of In-Cylinder Low-Pressure Direct Injection Strategy on the Atomization and Combustion Process of a Small-Scaled Gasoline Wankel Rotary Engine

To solve the problem of poor atomization and combustion in a small-scaled gasoline Wankel rotary engine (WRE) with low-pressure port injection mode, the numerical simulation was used to optimize the injection strategy. Firstly, the effects of in-cylinder temperature and pressure on gasoline atomization characteristics were studied, and the optimal injection timing was determined. Based on this, the influence of injection position, injection angle, and installation direction on the atomization, fuel-air mixing, and combustion processes of low-pressure direct injection (DI) small-scaled gasoline WRE was investigated. The results show that the injection angle is a key factor in determining the gasoline atomization characteristics. Injecting along the direction of rotor rotation causes the impingement between fuel bundle and combustion chamber pocket, resulting in the smaller Sauter mean diameter (SMD) and liquid penetration length (LPL). The installation direction of nozzle plays an important role in the airflow movement. When the nozzle is vertical-installed, the airflow repeatedly crosses to form multiple eddies, making the fuel to move more easily towards the front of combustion chamber. When the nozzle is parallel-installed at the lower edge of the installing zone and injecting along the direction of rotor rotation, the peak in-cylinder pressure is the largest and increased by 21% compared to the original port injection. By this injection strategy, the problem of incomplete combustion for the studied small-scaled gasoline WRE could be almost completely solved.

Numerical simulation and verification of rotor downwash flow field of plant protection UAV at different rotor speeds.

In aerial spraying of plant protection UAVs, the continuous reduction of pesticides is an objective process. Under the condition of constant flight state (speed and altitude), the change of pesticide loading will inevitably lead to the shift of lift force and rotor speed generated by UAV rotor rotation, which will change the distribution of the rotor flow field and affect the effect of aerial spraying operation of plant protection UAV. Therefore, the rotor speed of UAV is taken as the research object in this paper, and the adaptive refinement physical model based on the Lattice Boltzmann Method (LBM) is used to numerically simulate the rotor flow field of the quadrotor plant-protection UAV at different speeds. A high-speed particle image velocimeter (PIV) was used to obtain and verify the motion state of the droplets emitted from the fan nozzle in the rotor flow field at different speeds. The results show that, with the increase of rotor speed, the maximum velocity and vorticity of the wind field under the rotor increase gradually, the top wind speed can reach 13m/s, and the maximum vorticity can reach 589.64s -1. Moreover, the maximum velocity flow value is mainly concentrated within 1m below the rotor, and the maximum vorticity value is primarily concentrated within 0.5m. However, with the increase of time, the ultimate value of velocity and vorticity decreases due to the appearance of turbulence, and the distribution of velocity and vorticity are symmetrically distributed along the centre line of the fuselage, within the range of (-1m, 1m) in the X direction. It is consistent with the motion state of droplets under the action of the rotor downwash flow field obtained by PIV. The study results are expected to reveal and understand the change law of the rotor flow field of plant protection UAVs with the dynamic change of pesticide loading to provide a theoretical basis for the development of precise spraying operation mode of plant protection UAVs and improve the operation effect.

Flight Performance with Respect to Rotor Rotation Directions of Multirotor Aircraft

A multirotor electric vertical takeoff and landing (EVTOL) aircraft is specialized for intracity point-to-point urban air mobility services due to its advantages of efficient hover performance, high gust resistance, and relatively low noise. Because of its multiple rotors, rotor–rotor interference inevitably affects flight performance, mainly depending on inter-rotor distance and rotor rotation directions. It is assumed that there exists an optimal rotation direction for a given lot of multiple rotors. In this study, the aim is to investigate rotor–rotor interference for various rotation directions and the resulting flight performance. We propose a concept of rotor rotation direction that achieves the desirable flight performance in forward flight. The concept is called front-retreating/rear-advancing (FRRA), in which the retreating side of the front rotor and the advancing side of the rear rotor are aligned in a straight line. To this end, a multidisciplinary flight simulation framework was developed to predict the flight performance of a general multirotor EVTOL aircraft. It was found that the FRRA concept minimizes thrust loss due to rotor–rotor interference in high-speed forward flight. For a generic mission profile, the rotation direction set by the FRRA concept reduces the battery energy consumption by 7% in comparison to the rotation direction of unfavorable rotor–rotor interference in operation.

Evaluation of a Coating Process for SiO<sub>2</sub>/TiO<sub>2</sub> Composite Particles by Machine Learning Techniques

In this study, in order to optimize a fabrication process for SiO2/TiO2 composite particles and control their coating ratio (CTi), regression models for the coating process were constructed using various machine learning techniques. The composite particles with a core (SiO2)/shell (TiO2) structure were synthesized by mechanical stress under various fabrication conditions with respect to the supply volume of raw materials (V), addition ratio of TiO2 (rTi), operation time (t), rotor rotation speed (S), and temperature (T). Regression models were constructed by the least squares method (LSM), principal component regression (PCR), support vector regression (SVR), and the deep neural network (DNN) method. The accuracy of the constructed regression models was evaluated using the determination coefficients (R2) and the predictive performance was evaluated by comparing the prediction coefficients (Q2). From the perspective of the R2 and Q2 values, the DNN regression model was found to be the most suitable model for the present coating process. Moreover, the effects of the fabrication parameters on CTi were analyzed using the constructed DNN model. The results suggested that the t value was the dominant factor determining CTi of the composite particles, with the plot of CTi versus t displaying a clear maximum.

Structural layout and operating parameters for a large rotor of a direct-flow bucket wheel type aggregator

Introduction. The problem of accelerating and cheapening the construction of roads without reducing their quality can be solved by creating a complex of continuous units. Units, following each other, carry out the whole complex of works aimed at the construction of roads. The use of satellite navigation opens up broad prospects for full automation of units. Therefore, the overall goal is to create a complex of units that carry out the continuous construction of roads, mainly in automatic mode. One of the devices that make up the continuous units is a direct-flow bucket wheel type aggregator. The use of direct-flow bucket wheel type aggregators for soil development is constrained by insufficient theoretical substantiation of their parameters. Before analyzing the interaction of the elements of the working bodies of a direct-flow bucket wheel type aggregator with the soil, it is necessary to clarify the structural layout for the rotor of a direct-flow bucket wheel type aggregator.The method of research. Some design parameters of a direct-flow bucket wheel type aggregator are derived from logical reasoning. Other parameters of the direct-flow bucket wheel type aggregator are obtained by constructing schemes for the impact of the knife on the ground in the plane and spatial modelling. Initially, the rotor of a direct-flow bucket wheel type aggregator with a diameter of one meter was adopted for calculation.Results. The circular and end knives are assigned the numbers № 1, № 2, № 3, etc. as it approaches from the periphery of the rotor to the axis of its rotation. On the basis of the adopted methodology, the design of the knife attachment, the front and back corner of the circular and end knives have been clarified. An extremely small distance from the axis of rotation of the rotor to the nearest point of the knife is established. Hence the conclusion is made that in addition to a large rotor, in conjunction with it, it is necessary to install a small rotor. The circumferential velocity of the blade of no. 1 circumferential knife and the angular velocity of the large rotor are determined. It is customary to arrange the knives in three rows, that is, the rows of knives around the circumference are deployed at an angle of 120° relative to each other. The feed on the end knife was revealed, that is, the thickness of the layer cut by the end knife.Conclusion. On the basis of the adopted methodology, the geometric and mode parameters of a large rotor of a direct-flow bucket wheel type aggregator have been determined. An extremely small radius of location of the circular and end knives of the large rotor is established. To excavate the soil near the axis of rotation for the rotor of the direct-flow bucket wheel type aggregator, a small rotor with a higher angular velocity shall be coaxially installed. The direction of rotation of the small rotor shall be opposite to the direction of rotation of the large rotor in order to partially compensate for the reactive moment produced by the large rotor.

Development and Justification of a Self-Regulating System for Adjusting the Angle of Rotary Tiller Blade with a Vertical Rotation Axis

The article considers the problem of providing constant or almost constant values of the blade cutting angles during one rotation of the tiller rotor with a vertical rotation axis. Analytical expressions were obtained by analyzing the trajectory of the tiller knife/blade, which enable to determine the change of the blade cutting angles at a constant location and to define the patterns of this change in the ranges of (0...π) and (π...2π). The derived expressions and conclusions make it possible to adjust the location angle of the knife, using a pattern, in case of which the cutting angles of the knife will remain unchanged during one rotation of the rotor. This circumstance is important from the prospect of ensuring a uniform working mode of the rotary tiller.

Эффективность применения фитаз и ударно-дезинтеграторно-активаторной обработки сои для снижения фитиновой кислоты в гидролизатах соевого белка

The efficiency of phytase and impact-disintegrator-activator processing (IDAP) of soybean in obtaining protein hydrolysate from full-fat soybean flour to reduce phytic acid in the hydrolysate was shown. For the experiments, samples of full-fat soybean flour were used, obtained through soybean processing using two different methods: impact disintegration-activation processing (IDAP) and a grinder with a rotor-knife working element (RKP – rotor-knife processing). The IDAP of soybeans was conducted using a DEZI-11 disintegrator unit with six-row rotors rotating at a frequency of 210 s-1. The RKP was carried out using a Gamlux GL-CG mill with a rotor rotation frequency of 20500 rpm. Enzymatic treatment of the mixture of full-fat soybean flour and water (with a water-to-material ratio of 1:6) was performed using the enzyme preparation Phytaflow (with an activity of 20000 U/cm3), with different dosages of phytase added: 20; 40; 60, and 80 U/g of full-fat soybean flour. The enzymatic treatment was conducted at a temperature of 50°C for a duration of 120 minutes. As a result of the studies, it was found that the design of the working body of the chopper affects the degree of soybean degradation, the content of phytic acid in full-fat soybean meal, and the efficiency of phytase action in obtaining protein hydrolysate. The content of phytic acid in full-fat soybean meal obtained after processing on the impact-disintegrator-activator type unit is 12% lower than in full-fat soybean meal obtained after processing on the grinder with a rotary knife working body. Phytase was found to decrease the phytic acid content in protein hydrolysate obtained after processing soybeans with the impact-disintegrator-activator unit more effectively than in protein hydrolysate obtained after processing soybeans with the shredder with the rotary knife-type working body. The hypothesis of the effect of IDAP soybean on the efficiency of phytic acid reduction and enzymatic phytase hydrolysis was confirmed and showed a high degree of significance. The reduction of phytic acid in full-fat soybean meal and protein hydrolysates obtained from it is of great practical importance as it allows to create functional foods with high digestibility and protein bioavailability and to increase the doses of inclusion of full-fat soybean meal in starter feeds of animals, birds, and aquaculture.

Technological methods of improvement and influence on the rotor rotation speed on efficiency of barley hushing machine

The article provides the results of a study of the impact of different parameters and the process of peeling barley in the production offeed. Theoretical studies and analysis of the structures of the peelers and the proposed horizontal peeler have suggested that the rational rotation rate of the rotor during barley peeling will be between 1500 and 1800 rpm. After the studies, a number of factors were tested which influenced and increased the efficiency of barley peeling, which determined the effect of rotor rotation frequency, processing duration, the amount of product pass through processing during, the peeler. Based on the research, the technological parameters of the peeler have been developed andimproved.

Torque Density Improvement of a Low-Speed High-Torque Swirling Actuator Driven by Electromagnetic Radial Force With Integrated Mechanical Gears

The torque density improvement of a low-speed high-torque swirling actuator is presented in this article. The swirling actuator is driven by the electromagnetic radial force and integrated mechanical gears. The electromagnetic radial force generates the circular motion of the swirler, which is converted into the low-speed rotor rotation by the mechanical gears. First, the dimensions of the swirler with 12-pole permanent magnets are optimized to enhance the electromagnetic radial force by analytical calculation and three-dimensional finite-element analysis. Second, an improved gear set with a reduced pressure angle and an increased transmission ratio is designed. The gear efficiency and torque are investigated analytically considering the friction loss. Two prototypes are designed, and the experimental results exhibit that the peak torque density is improved from 27 to 64 Nm/L with a small volume of 0.16 L.

Dynamic Phasor Finite-Element Modeling of a DFIG for Grid Connection Studies

Co-simulation studies of electric power systems and electric machines have been always a challenge. In order to reduce the simulation time to a reasonable value, lumped-parameter Electric-Machines models are commonly used in electric power system modeling software packages to avoid the heavy computational burden of more accurate modeling methods especially Finite Element Method (FEM) on the expense of less accuracy. The proposed technique in this paper combines the Dynamic Phasor Modeling technique for power system simulations with FEM to accurately model the DFIG while connected to the grid. The utilization of dynamic phasors enables adopting large simulation time-steps resulting in a significant reduction in the simulation time compared to the conventional time-domain FEM modeling. The mathematical foundation of the proposed modeling method is presented including the generator's core saturation. Custom-written C++ codes have been developed by the authors to execute the new dynamic phasor FEM algorithm and the conventional time-domain FEM in order to fairly compare their accuracy and numerical performances. As the proposed method combines time and frequency domains, a unique capability of modeling the rotor movement can be achieved. The rotation can be represented by physically incrementing the rotor and airgap mesh as in regular time-domain solvers, by mathematically representing the rotation using the Virtual Blocked Rotor method as in frequency-domain solvers, and the proposed method of combining the two aforementioned approaches. The three methods of modeling rotor rotation are discussed and their simulation results are compared to give a guide to choose the proper method for the different modeling targets. The results show that the proposed dynamic phasor FEM is capable of producing comparable results to the traditional time-domain solver at a substantially reduced simulation time.

Study of ACS of rotor rotation frequency and gas temperature with accurate regulators in the control loop of a gas turbine engine

This article discusses the automatic control system for parameters (rotor speed and gas temperature) of a gas turbine engine based on clear logic controllers. It is proposed to use clear logical controllers, consisting of a comparing device, a fuzzifier, an inference block with a system of production rules and with given membership functions of clear terms of variables, and a defuzzifier. Precise logical controllers, using the membership functions of precise terms, in the control loops of the object’s influence stably maintain the overshoot time.

Two Cooling Approaches of an Electrohydraulic Energy Converter For Non-Road Mobile Machinery

The energy efficiency of non-road mobile machinery can be improved by using e.g., an electric drive system as a servo controller of a hydraulic machine to get an efficient electro-hydraulic (EH) converter. However, the cooling of EH devices require more understanding and new innovations. This work presents a design of a 7-kW integrated EH machine and studies its electric motor heat transfer phenomena both experimentally and numerically. Further, to better match the torque and speed performances of the permanent magnet synchronous motor (PMSM) and the hydraulic machine a planetary step-down gear is utilized to triple the output torque of the PMSM. The integrated motor and gear system is then connected to a bent axis piston hydraulic machine, which is capable of operating both as a motor and a pump. Two different electric motor cooling approaches are investigated. The first cooling approach is to use some hydraulic oil inside the motor-gear chamber to let it flow freely as a result of the rotor rotation and move the losses to the surface of the converter cover, which is equipped with some air cooling fins. In the second approach, the oil flows through the converter and removes the losses more effectively. Motor losses and thermal behaviour are studied within these two cooling approaches. Computational fluid dynamic (CFD) simulations are performed to find how the coolant is distributed inside the machine and how heat is distributed in the device.

Research of the crop seed unloading process from the treatment chamber of a rotary seed treater

Purpose. Enhancing the productivity of the process of layer-by-layer application of protective agents on the seeds of agricultural crops through the justification of the shape of the unloading window of the seed treatment chamber of rotary batch treaters. Methods. The research uses an analytical and experimental methods using Microsoft Office software environments. Results. The analytical dependence of the ratio of the width of the live cross-section of the seed flow to the width of the unloading window on the central angle of the window girth and the experimental dependence of the seed unloading time from the processing chamber on the mass of its portion and the rotor rotation frequency were obtained. Conclusions. The ratio of the width of the live section of the flow of processed seeds to the width of the unloading window increases proportionally with the increase in the central angle of the window. The throughput of an unloading window with a larger window width is greater than the throughput of an unloading window with a smaller window width for the same area. The time of discharge of processed seeds depends on both the mass of its portion and the frequency of rotation of the rotor. At the same time, the seed unloading time from the processing chamber increases with the increase in the weight of its portion and at a rotor speed of 250 rpm is 4.3 s for a seed portion weight of 3.5 kg and 6.9 s for 14 kg portion weight. The time of seed discharge from the processing chamber decreases with an increase in the rotor rotation frequency, and for 10.5 kg seed portion weight, it is 5.4 s at a rotor rotation frequency of 150 rpm and 4 s at a rotor rotation frequency of 250 rpm. Keywords: seeds, treatment chamber, seed treater, layer treatment, protective preparations, unloading.

On the modeling of boundary conditions for determining the critical speeds of rotation of rotors

The article is devoted to the definition of boundary conditions that allow achieving adequate results when calculating the critical speeds of rotation of rotors based on finite element models. Experimental determination of the frequencies of free vibrations of a laboratory rotor on ball bearings was carried out using a vibration measuring complex developed by the authors. Numerical studies of the free vibrations of a laboratory rotor and a cylindrical pipe with a wall thickness to length ratio of 1/10 were performed on the basis of a three-dimensional finite element model under various boundary conditions. Movable and fixed cylindrical hinges corresponding to floating bearings are used as supports in the calculation scheme of the laboratory rotor. Due to the fact that the dimensions of the bearings along the length of the shaft are small compared to the total length, it is assumed in the calculation model that the shaft is hinged along the edges at separate points of one circle on each bearing. Shaft mounting options at two, four and eight points are considered. The options for fastening a cylindrical pipe in the extreme sections at two points, a quarter of a circle and a full circle are considered. Comparison of experimental and numerical results, solutions obtained analytically and on the basis of the finite element method is carried out. An analysis of the modes of natural vibrations showed that with various options for fixing a cylindrical pipe, vibration modes arise associated with the deformation of the pipe as a shell. For example, when fixing a pipe along a quarter of a circle, among the forms №1-№10, only the second corresponds to the deformation of the pipe as a beam. The results of the study of free vibrations of a laboratory rotor show that the best option for boundary conditions, which makes it possible to approach the results of the experiment, is fastening on each bearing at two points located on the neutral line of the cross section when the rotor is bent. Numerical studies of the eigen frequencies of a cylindrical pipe show that it is with this type of boundary conditions that one can obtain results that are closest to the analytical solution.

An eccentric-structured hybrid triboelectric-electromagnetic nanogenerator for low-frequency mechanical energy harvesting

With the increasing aggravation of the environmental pollution and energy crisis, exploiting clean and renewable energy becomes imperative for human existence and development. In this paper, an eccentric-structured hybrid triboelectric-electromagnetic nanogenerator (EHNG) is proposed to harvest low-frequency mechanical energy. It mainly contains two parts, – a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG). Exploiting the unique eccentric structure, the EHNG can effectively transfer one-dimensional mechanical motion of an object to the rotation of the eccentric rotor, resulting in electricity generation. In comparison to a separate energy harvesting unit, the hybrid nanogenerator operates beyond the single energy harvesting mode, showing preferable electrical output performances including a broader output range and shorter time of voltage boosting. In terms of energy storage, the EHNG provides not only a higher saturation charging voltage and continuous charging from the TENG part, but also a rapid charging speed in the early charging phase from the EMG part. As a practical power source, the EHNG is shown to be capable of directly powering LEDs. The present work develops an effective and sustainable technique to maximally harvest mechanical energy from the environment.