Rotor Parts Research Articles

An important source of preanalytical error in medical laboratories: centrifugation

Abstract Centrifugation separates particles within the specimen according to their shape, dimensions, and density and basically can be defined as a separation method. The centrifuge is an essential device in medical laboratories to prepare the serum, plasma, and urine samples for analysis. It is basically an electric device composed of the stationary (motor) and the motile (rotor) part. The centrifugation depends on two main variables: relative centrifugal force (RCF) and centrifugation time. The physical impact separating the specimen into its components in the centrifuge known as RCF is expressed as the multiples of gravitational acceleration (×g). RPM, defined as the number of rotations of the centrifuge per minute, shows the speed of the centrifuge. RCF value can be calculated by using RPM, and the centrifuge radius. Because models and sizes of centrifuges vary considerably, the use of gravity (g) forces instead of RPM is suggested. The centrifuges can be classified according to their usage, speed, technical specifications, and rotor type. An accurate and precise centrifugation process is essential to prevent errors in the preanalytical phase. The purpose of this document is to ensure the standardization of a good, precise protocol for the centrifugation process among the medical laboratories.

Wet Modal Analyses of Various Length Coaxial Sump Pump Rotors with Acoustic-Solid Coupling

The dynamic characteristics of the rotor components were determined using a first-order modal model of the rotor components for various sump pump shaft lengths for actual working environments. By employing ANSYS-Workbench software, this paper uses a fluid-solid coupling analysis to calculate the reaction forces of the fluid on the rotor with results, which is then used in dry and wet modal analyses of the rotor parts to calculate the vibration modal characteristics with and without prestresses. The differences between the wet and dry modal characteristics were compared and investigated by ANSYS. The results show that increasing the sump pump shaft length reduces the first-order natural frequency of the prestressed rotor components. The structure also experiences stress stiffening, which is more obvious in the high-order modes. The natural frequency of the rotor in the wet mode is about 16% less than that in the dry mode for the various shaft lengths due to the added mass of the water on the surface which reduces the natural frequency. In the wet modal analysis, when the structure is in a different fluid medium, the influence of its modal distribution will also change, this is because the additional mass produced by the fluid medium of different density on the structure surface is different. Thus, the wet modal analysis of the rotor is important for more accurate dynamic analyses.

Design and analysis of a radial centrifugal pump for cryogenic helium based application

A centrifugal pump is a rotordynamic machine that has wide spread application in industry. After analytical design, it is important to check the machine performance by some numerical method to be assured of machine performance before manufacturing. In the present study, a centrifugal pump conforming to a specific process requirement for cryogenic helium fluid has been developed in detail. This involves analytical design derivation of the stator and rotor part, computer aided design (CAD) modelling, meshing and detailed computational dynamic analysis (CFD) analysis. In line with analytical prediction, it is seen from simulation results that the designed machine meets the given requirements with an achieved hydraulic efficiency of 88%.

Energy harvesting applications using 3D-printed coreless generator

3D-printed coreless generator has been presented for energy harvesting applications using permanent magnet as source of external magnetic field in the rotor. The phototype of proposed coreless generator is built using 3D-printer with Black Polylactic Acid (PLA) as a filament for stator housing, rotor and other parts. The major parts of the proposed coreless generator are the stator, which has four coils of winding copper wire and the rotor with eight permanent magnets which are arranging N and S magnet poles alternately. This research is conducted to determine how much power can be generated from the proposed 3D-printed permanent magnet generator. The prototype permanent magnet generator is tested with rotational speed and load condition. The experimental results have been shown that the coreless generator can generate the electrical energy up to 5 W at 6000 rpm.

Effect of number of permanent magnetic poles on 3D printed coreless generator rotor

3D-printed coreless generator using rotors with 4 poles permanent magnet and 8 poles permanent magnet as source of external magnetic field has been presented for energy harvesting applications. The prototype of proposed coreless generator is built using 3D-printer with Black Polylactic Acid (PLA) as a filament for stator housing, rotor and other parts. The major parts of the proposed coreless generator are the stator, which has four coils of winding copper wire and two rotors with four permanent magnet and eight permanent magnets which are arranging N and S magnet poles alternately. The prototype permanent magnet generator is tested with rotational speed and load condition. The experimental results have been shown that the coreless generator can generate It was found that 3D-printed coreless generator can generate electric energy up to 10300 mW for rotor with eight permanent magnets and 9000 mW for rotor with four permanent magnet at 5000 rpm, respectively.

Selection of Subtractive Manufacturing Technology Versus Additive Manufacturing Technology for Rapid Prototyping of a Polymeric Product

The Additive Manufacturing (AM) industry has expanded steadily, occupying the market very quickly. New types of 3D printers have appeared and new types of polymeric and composite materials have been developed for these printers. Thus it passed very quickly from the stage in which the parts that were made by rapid prototyping (RP) only to be exposed (demonstration parts) to stage AM the parts are fully functional. Of course, the future of AM is still on the horizon, it is barely visible. The other technologies for forming the geometry of the part, ie subtractive manufacturing technology and formative manufacturing technology are still the basis of industrial production. Each technology has its own advantages and disadvantages and is chosen on a case-by-case basis, depending on the objectives pursued. In this paper, a study is made on the rapid prototyping of a single pump rotor part. The material of the piece is of polymer type, ABS. The piece was made in two variants: by additive manufacturing technology (PolyJet) and by subtractive manufacturing technology (milling). After processing, several parameters were followed, such as the functionality of the part, the surface quality, the mechanical tensile strength, the dimensional accuracy, and last but not least the manufacturing cost and the duration of the manufacturing cycle. The data thus obtained were processed with an artificial intelligence program for decision making.

Thermal Modeling and Experimental Validation in the Rotor Region of Hydrogenerator With Different Rotor Structures

Thermal management is often considered a bottleneck in the pursuit of the next generation hydrogenerator in the electric power system. Overheating of the complex rotor parts has become one of the main problems affecting safe and stable hydrogenerator operation. In this paper, a 250 MW hydrogenerator is analyzed. The transient electromagnetic field of the hydrogenerator is calculated and the losses of the rotor parts are obtained. The rotation of the hydrogenerator rotor is considered. Three-dimensional fluid and thermal mathematic and physical models of the hydrogenerator are established. The loss values from electromagnetic field calculations are applied to the rotor parts as heat sources in the temperature field. After solving the fluid and thermal equations of fluid-solid conjugated heat transfer, influence of the structures of rotor support plate, rotor pole body insulation, and rotor excitation winding on the fluid flow and temperature distribution in the rotor region of hydrogenerator is studied using the finite volume method. The calculated temperature result of rotor excitation winding is compared with the measured value. The calculated temperature result agrees well with the measured value. It provides an important reference for optimizing the rotor structure of the larger hydrogenerator.

The Detection of Inter-Turn Short Circuits in the Stator Windings of Sensorless Operating Induction Motors

This work proposes an alternative strategy to the use of a speed sensor in the implementation of active and reactive power based model reference adaptive system (PQ-MRAS) estimator in order to calculate the rotor and stator resistances of an induction motor (IM) and the use of these parameters for the detection of inter-turn short circuits (ITSC) faults in the stator of this motor. The rotor and stator resistance estimation part of the IM is performed by the PQ-MRAS method in which the rotor angular velocity is reconstructed from the interconnected high gain observer (IHGO). The ITSC fault detection part is done by the derivation of stator resistance estimated by the PQ-MRAS estimator. In addition to the speed sensorless detection of ITSC faults of the IM, an approach to determine the number of shorted turns based on the difference between the phase current of the healthy and faulty machine is proposed. Simulation results obtained from the MATLAB/Simulink platform have shown that the PQ-MRAS estimator using an interconnected high-gain observer gives very similar results to those using the speed sensor. The estimation errors in the cases of speed variation and load torque are almost identical. Variations in stator and rotor resistances influence the performance of the observer and lead to poor estimation of the rotor resistance. The results of ITSC fault detection using IHGO are very similar to the results in the literature using the same diagnostic approach with a speed sensor.

Evaluation of possibility of integrating one-dimensional numerical computational methods for modeling radial displacements of GTE rotor parts into the mathematical model of active clearance control system

Evaluation of possibility of integrating one-dimensional numerical computational methods for modeling radial displacements of GTE rotor parts into the mathematical model of active clearance control system

A review of mathematical modelling techniques for advanced rotorcraft configurations

The paper will review the development and application of the mathematical modelling of the advanced rotorcraft configuration, including compound helicopter configurations and tilt-rotor vehicles. The mathematical model is the basis for the design of the flight control system and an essential tool to assess the flying and handling qualities for helicopters. As the helicopter is a multi-body system, the mathematical modelling of helicopter should consider the coupling effects among motion, inertia, structure, and aerodynamics, as well as the unsteady and nonlinear characteristics, to give the physical principles and mathematical expression of each part. Therefore, the mathematical modelling of a helicopter is a process of analysing and synthesizing different hypotheses and subsystem models. Moreover, the advanced helicopter configuration puts forward higher requirements for the helicopter mathematical modelling in terms of the aerodynamic interference, blade motion characteristics, and manoeuvre assessment. The critical issues of helicopter modelling, especially the modelling of the advanced rotorcraft configurations, will be illustrated in this paper. The emphasis is put on the modelling of rotor aerodynamics and aerodynamic interaction among the rotor, fuselage, and other parts. Integrated modelling methods and the manoeuvrability investigation are also the foci of the paper. Suggestions for future research on helicopter flight dynamics modelling are also provided.

Configurational and Constitutional Dynamics of Enamine Molecular Switches.

Dual configurational and constitutional dynamics in systems based on enamine molecular switches has been systematically studied. pH‐responsive moieties, such as 2‐pyridyl and 2‐quinolinyl units, were required on the „stator“ part, also providing enamine stability through intramolecular hydrogen‐bonding (IMHB) effects. Upon protonation or deprotonation, forward and backward switching could be rapidly achieved. Extension of the stator π‐system in the 2‐quinolinyl derivative provided a higher E‐isomeric equilibrium ratio under neutral conditions, pointing to a means to achieve quantitative forward/backward isomerization processes. The „rotor“ part of the enamine switches exhibited constitutional exchange ability with primary amines. Interestingly, considerably higher exchange rates were observed with amines containing ester groups, indicating potential stabilization of the transition state through IMHB. Acids, particularly BiIII, were found to efficiently catalyze the constitutional dynamic processes. In contrast, the enamine and the formed dynamic enamine system showed excellent stability under basic conditions. This coupled configurational and constitutional dynamics expands the scope of dynamic C−C and C−N bonds and potentiates further studies and applications in the fields of molecular machinery and systems chemistry.

Application of Ultrasonic Phased Array Detection Technology in Steam Turbine Components

Ultrasonic phased array detection technology has the characteristics of fast, high sensitivity and recordable. The application of ultrasonic phased array detection technology to diaphragm, rotor, bolt and other turbine metal parts can effectively improve the detection rate of micro defects. At the same time, the development of reliable detection process can avoid the limitations of its detection and ensure the safety and reliability of turbine metal equipment.

Finite-element/boundary-element transient modelling of hysteresis motors

This paper presents a transient study of hysteresis motor based on the proposed hybrid method of finite element method- boundary element method (FEM-BEM) in which the Jiles-Atherton (J-A) vector hysteresis model of the hard-magnetic material of the rotor is incorporated. The air–gap region is modeled by BEM in order to avoid the discontinuity in the FEM equations due to J-A hysteresis model and the rotor movement and, therefore, the eddy current effect is taken into account in the rotor part, for the first time. To the best of the author’s knowledge, the prior time-dependent numerical models have ignored the torque component caused by eddy currents in the rotor of hysteresis motor, due to difficulty in rotating the mesh in the rotor region and the related convergence problems. The proposed model is employed to study the phenomenon of short period over-excitation in hysteresis motors. A comparison is done between the proposed time-domain model and the frequency-domain finite element model of the hysteresis motor.

저널 래버린스 실이 임펠러 추력 및 누설에 미치는 영향

In recent years, turbomachinery pursue high speed operations in compact volume to achieve high specific power. An impeller operating at high rotating speeds increases the compression ratio and results in significant axial thrust forces which must be balanced with balance piston or thrust bearing. A leakage flow flowing through Labyrinth seals located in the gap between the rotor and stator parts also influences the magnitude of the thrust forces. This study develops a predictive model of an impeller coupled with a labyrinth seal to predict the resulted axial thrust force. Firstly, a comparison between the predicted cavity pressure and leakage to the published test data validates the bulk-flow model of the labyrinth seal used in the paper. Then the coupled model of the impeller to the labyrinth seal is verified by comparison of the predicted pressure distributions and leakage flow rates to those from CFD analyses using the k-ε turbulence model. Additionally, the study reports the effects of the labyrinth seal design, operating speed, and lubricant type on the axial thrust force and the leakage flow rate. The results show that the labyrinth seal decreases the leakage flow rate but increases the axial force, implying the need of trade-off between the impeller axial force and leakage flow rate. As the gap between the impeller and casing wall decreases, both the impeller axial force and leakage flow rate decrease. The impeller axial force and the leakage flow rate predicted using refrigerant gas are smaller and less sensitive to the change of the labyrinth seal design when compared to those predicted using air.

ОСОБЕННОСТИ ОБРАБОТКИ ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ ПРИ ОПРЕДЕЛЕНИИ КОЭФФИЦИЕНТА ТЕПЛООТДАЧИ В МАСЛЯНОЙ ПОЛОСТИ ОПОРЫ ГТД

The development of gas turbine technology is accompanied by an increase in temperatures, pressures, and airflow velocity in the gas path. Increasing operating cycle parameters for gas turbine engine complicates the tasks of ensuring the permissible temperature state of engine parts, requires improving the methods of their calculation and design. This fact fully applies bearing assemblies, especially those operating in a hot environment, and causes interest in the study of thermohydraulic processes in the bearing chamber, which determines the temperature state of the rotor parts. The necessity of pressurizing the seals leads to the presence of the oil-air mixture in the bearing chamber. A wide range of operating parameters, flow inhomogeneity, phase disequilibrium, and phase separation significantly complicate the mathematical description of processes in the bearing chamber, including the use of CFD-modeling. Therefore, considerable attention is paid to experimental research. The experimental results are used not only to verify mathematical models but also to obtain generalizing dependencies. Most often, the desired value is the heat transfer coefficient in the oil cavity of the support. The article deals with the heat transfer features in the near-wall zone of the gas-turbine engine bearing chamber which were associated with the presence of oil-air flow. Also, approaches to the experimental determination of the heat transfer coefficient were analyzed and an appropriate system for measuring the local temperatures of the media was formed. The values of the error of the experimental heat transfer coefficient and the degree of influence of the determining factors were estimated. The contribution of the non-uniformity of the temperature field in the walls of the chamber and the uncertainty in the value of the temperature of the flow core was determined. The advantages of using the averaged heat transfer coefficient for engineering calculations and the significant influence of the averaging method on its value were also shown. Averaging over the heat flux density corresponds most accurately to the tasks of such calculations, at which the total heat flux through the chamber walls does not change.

МЕТОД ИССЛЕДОВАНИЯ ВИБРАЦИИ КОРПУСА АВИАЦИОННОГО ДВИГАТЕЛЯ ПРИ ОТРЫВЕ ЛОПАТКИ ВЕНТИЛЯТОРА

Following the Certification Specifications, at the design stage, the structural strength of the aircraft is calculated when the blades abruption and the engine bearing is destroyed, which cause large vibrations. At the finalization stage, these calculations should be confirmed by tests. The most effective way of dynamic test operation now is a numerical simulation because it makes it possible to study the influence of a large number of different factors, to analyze structural vibrations in those modes that are impossible or dangerous to reproduce in full-scale tests, significantly saving time and material resources.Studies of transient vibrational processes for a simplified calculation model of linear deformation of bearing assembly were performed. The most dangerous case of damage to the fan blade abruption is considered.The engine is attached to the pylon at five points. Two attachment points to the front traverse and two attachment points to the rear traverse are hinges with axes parallel to the axis of the engine. The fifth point is a hinge with an axis perpendicular to the vertical plane. At this point, the engine is attached to the pull rod. In the first approximation, we assume that the body is solid, and its center of mass is located on the axis of rotation of the rotor. We consider traverses as elastic beams working in bending, and the rod for lifting the thrust as an elastic rod working in tension. We simulate the rotor with a solid body on bearings, since the deformations of the rotor parts are small in comparison with the deformations of the bearings and the lowest natural frequency of the oscillations of the rotor as an elastic body is an order of magnitude higher than the frequencies of the rotors on the bearings.The frequency response of the rotor, the dependence on the time of movement of the support sections, and the orbits of the centers of the support sections of the rotor relative to the stator are obtained. The frequency response of the engine with the rotor, the dependence on the time of the generalized stator coordinates is constructed. An analysis of the applicability of the developed model and calculation method for different cases of damage to the rotor and its bearings is carried out. The importance and prospects of continuing research with nonlinear calculation models are shown.

Analysis of Standby Losses and Charging Cycles in Flywheel Energy Storage Systems

Aerodynamic drag and bearing friction are the main sources of standby losses in the flywheel rotor part of a flywheel energy storage system (FESS). Although these losses are typically small in a well-designed system, the energy losses can become significant due to the continuous operation of the flywheel over time. For aerodynamic drag, commonly known as windage, there is scarcity of information available for loss estimation since most of the publications do not cover the partial vacuum conditions as required in the design of low loss energy storage flywheels. These conditions cause the flow regime to fall between continuum and molecular flow. Bearings may be of mechanical or magnetic type and in this paper the former is considered, typically hybridized with a passive magnetic thrust bearing. Mechanical bearing loss calculations have been extensively addressed in the open literature, including technical information from manufacturers but this has not previously been presented clearly and simply with reference to this application. The purpose of this paper is therefore to provide a loss assessment methodology for flywheel windage losses and bearing friction losses using the latest available information. An assessment of windage losses based on various flow regimes is presented with two different methods for calculation of windage losses in FESS under rarefied vacuum conditions discussed and compared. The findings of the research show that both methods closely correlate with each other for vacuum conditions typically required for flywheels. The effect of the air gap between the flywheel rotor and containment is also considered and justified for both calculation methods. Estimation of the bearing losses and considerations for selection of a low maintenance, soft mounted, bearing system is also discussed and analysed for a flywheel of realistic dimensions. The effect of the number of charging cycles on the relative importance of flywheel standby losses has also been investigated and the system total losses and efficiency have been calculated accordingly.

INCREASE DURABILITY AND RELIABILITY OF CENTRIFUGAL SEPARATORS BY USING NEW MATERIALS

The urgent task of increasing the durability and reliability of centrifugal separators under the conditions of corrosive erosion of treated media with a high content of chlorine ions and abrasive inclusions predetermined the transition to the manufacture of rotor parts from corrosionresistant, high-plastic steels of the austenitic and austenitic-ferrite class instead of the previously used high-strength and low-elastic steel martensitic class. The use of highly ductile corrosion-resistant steels with high fracture toughness characteristics eliminates the possibility of brittle fracture of rotors. However, these steels have a low yield strength, which makes it necessary to conduct hardening rotors for highly loaded body parts in the field of centrifugal forces. Hardening provides elastic operation of rotor parts during operation, creates fields of residual stresses that partially compensate for stresses arising in the operational mode. In this work, the stress-strain state and the bearing capacity of the rotor of a separator of a self-unloading type with a diameter of 500 mm, made of parts that have passed the hardening cycle, are investigated. Three variants of the rotor of the same design were investigated, differing in the materials of the body parts, for which austenitic steel grades 06X17H13M3-VD, ALIII-23-43-02 and austenitic-ferritic grades 10X26H5M, ALIII-23-24 were used. The stress-strain state of the rotor was investigated by the numerical finite element method for an axisymmetric problem. When choosing a design scheme, the following assumptions are made: the rotor is an axisymmetric design with an axisymmetric load; initial stresses are not taken into account; the load from the influence of the medium being treated is perceived by the rotor body parts (excluding the internal piston). The boundary conditions for the rotor are determined based on the analysis of the interaction of the hub with the shaft (the landing of the rotor on the shaft is carried out with the hub fixed in the axial direction). During the loading process, the residual deformation was determined by steps by the strain gauging method, and the diameters of the parts were also measured with a micrometer with an accuracy of ± 0.01 mm. Strain gages were glued at the circuits of the concentrators: holes for the cover stopper relative to the base, unloading windows, holes in the tightening rings, as well as on the ends of the base and the tightening ring. Thus, based on the results of the study, it can be recommended for the manufacture of rotors of separators of steel of austenitic-ferrite class, providing the necessary safety margins of structures.

Enhanced mass transfer and reduced pressure drop in a compound rotating zigzag bed

A rotating zigzag bed (RZB) had achieved the commercial application of Higee in continuous distillation processes, and then a compound rotating zigzag bed (CRZB) was developed from the RZB. The CRZB rotor was composed of a disk layer including several perforated concentric circular ripple disks fixed on a perforated rotating ring at the inner part of the rotor and several coupled rotational-stationary baffles at the outer part of the rotor. And a stationary four-arm liquid distributor was located at the eye of the CRZB rotor. The effective interfacial area (ae) and local liquid-side mass transfer coefficient (kL) of the CRZB rotor were measured by experiments of a chemical absorption of CO2 in NaOH solution, and the local gas-side mass transfer coefficient (kG) of the CRZB rotor was measured by experiments of a stripping of ethanol from an ethanol-water mixture by air. The gas pressure drop across the CRZB was measured with air-water system. Effects of gas flow rate, liquid flow rate and rotational speed on these mass transfer parameters and gas pressure drop were investigated. The stationary four-arm liquid distributor led to stronger end effect of the CRZB rotor than that of the RZB rotor. The end effect of the CRZB rotor had significant effect on the ae and kL of the rotor. The ae of the CRZB rotor was much higher than that of the RZB rotor because the total space in the disk layer of the CRZB rotor served as mass transfer zones and the CRZB rotor had stronger end effect than the RZB rotor. The local volumetric liquid- and gas-side mass transfer coefficients (kLae and kGae) of the CRZB rotor reached 2.3 times higher than those of the RZB rotor at a higher liquid flow rate and a rotational speed of 1200 rpm. The gas pressure drop across the CRZB was lower than that across the RZB, because the coupled rotational-stationary baffles were abandoned at the inner part of the CRZB rotor, which reduced the gas flow resistance and led to a lower pressure drop compared to the RZB. Thus, mass transfer was enhanced and gas pressure drop was reduced in the CRZB compared to the RZB, which showed the CRZB had excellent potential as a representative of the second-generation RZB for commercial applications.

Simulation of a gas turbine engine rotor assembly

The quality of aircraft and rocket engines depends primarily on the geometric accuracy of assembly units and parts. Mathematical models implemented in the form of computer models are used to predict quality indicators (in particular, assembly parameters). The work presents a numerical model for predicting assembly parameters of the rotors based on the use of actual surfaces of the parts obtained as a result of measurement on coordinate measuring machines and of mathematical modeling. Aircraft engine turbine rotor parts surfaces are measured on a coordinate measuring machine. Experimental assemblies of three parts were carried out. The measurement error of the parts does not exceed 5 µm, of assembly – 10 µm. Face and radial run-outs were measured for four positions of the disc and retainer in the shaft assembly, with run-outs ranging from 0.08 mm up to 0.1 mm. Calculations of face and radial run-outs of the disc with respect to the base surfaces of the shaft were made using the developed digital model. Relative deviations of the calculated values from the experimental values do not exceed 10%.