Rotor Circumference Research Articles

Modeling of process-induced geometrical deviation in broaching for fir-tree slots

Broaching is a key technology for the manufacturing of fir-tree slots. Due to the high-temperature-resistant materials used, a high mechanical load is applied to the workpiece during machining. Because of the filigree workpiece structure, the high mechanical load leads to a geometrical deviation of the machined webs which are formed by two consecutive fir-tree slots on the rotor circumference. Therefore, a methodology was developed to predict the resulting geometrical workpiece deviation. It was shown and validated in analogy experiments that the minimum achievable deviation is a function of the web geometry independent of the number of calibration cutters.

Investigation on the Flow Angle of a Mixed Flow Turbocharger Turbine Under Steady State Operating Conditions Authors

Turbocharger is widely used in automotive field for the capability to extract or boost the downsizing internal combustion (IC) engine as it has been considered as a way to provide highly efficient of small engine. Turbocharger also reduces the fuel consumption as well as the carbon dioxide (CO2) emission. Turbine is one of the main components of a turbocharger. Generally, this study is mainly focusing on a mixed flow turbine that work under steady flow operation. Numerical work using Computational Fluid Dynamics (CFD) is presented in this report. This report aims to compare the flow angle analysis of three selected cases under steady state flow operating conditions. A 3D modelling on a mixed flow turbine is generated accordingly to ‘Rotor A’ design by using a commercial software of Ansys CFX. Three selected cases were selected in order to compare the flow angle at the mid span circumference location at vane and rotor inlet. The simulation results show the capabilities of the 3D model developed in capturing the trend of available experiment data at turbine speed of 48kRPM. The mixed flow turbine achieves optimum total-to-static efficiency of 74.16 % at velocity ratio of 0.65 with mass flow rate of 0.5kg/s. Besides that, the results shown that the flow angle distribution at the rotor inlet is varied throughout the rotor circumference location between the three cases. Case 2 achieved the optimum incidence angle compared to the other cases thus showing the impact of incidence angle in determining the turbine performance.

Analysis of Selected Operating States of the Line Start Synchronous Reluctance Motor Using the Finite Element Method

The article presents the results of work on an effective numerical study of selected transient states of a low-power electrical machine. The object of detailed research was a synchronized squirrel-cage induction motor. Its ability to work at a synchronous speed was enabled by obtaining reluctance torque, caused by an imposed asymmetry between the direct and quadrature reluctances of the rotor. The difference between the reluctances was achieved by changing the rotor geometry by milling additional deep grooves. The modifications of the rotor did not damage the continuity of the rotor cage. Imposed lots were arranged symmetrically around the rotor circumference. In order to study the performance of the modified motor, a parameterized, numerical model of the machine was developed to evaluate the impact of the geometry of the slots. The developed three dimensional (3D) model of the electromagnetic phenomena in the studied magnetic circuit employs the finite element method (FEM). The model takes into account the saturation of the machine’s magnetic circuit and the skew of the rotor cage bars as well as the mechanical equilibrium of the terrain system including the moment of inertia and frictional torque in the bearings as well as the load torque resulting from the operation of the internal fan. The simulation study concerned the starting process of the machine under different values of the load. The influence of the supply voltage phase angle at the moment of start-up and the initial position of the rotor in relation to the stator was investigated. In order to calibrate the model, tests of the physical object were performed. The corrections introduced concerned the magnetization characteristics of the magnetic circuit. The results obtained confirm the correctness of the adopted strategy of testing the operational properties of the considered engine.

Asynchronous slip-ring motor synchronized with permanent magnets

Abstract The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a short-circuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM) – Fig. 3, and the Linear Permanent Magnet (IPM) – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.

Relevance and prospect of development of imitating modelling at research of working process of the excavator

A scraper design with rotary loading. Substantiates the location of the rotor blades to provide a bucket load and complete unloading. The question of filling the bucket scraper height and location of the rotor shaft to operate the scraper without pusher. Presented calculated according to the definition of the scraper bucket capacity with the rotor load, the radius of the rotor circumference and the height of the side walls of the bucket. The recommendations of the angle of inclination of the rear wall of the bucket to the vertical and location podnozhevoy plate.

Friction of outer rotor affecting friction torque characteristics in an internal gear pump

This article presents the friction torque in an internal gear pump and the friction force between an outer circumference of an outer rotor and a body, which causes a significant loss, has been investigated. When in use at a high pressure, the pump has a large friction torque due to the friction force acting on the outer rotor circumference. This friction force is caused by imbalanced force acting on the outer rotor. As well as by a positioning suction and a delivery port, the force can be reduced by setting a suction pressure recess in a section of the outer rotor circumference. In this study, through the measurement of the friction torque in an actual pump and the pressure distribution on the outer circumference of the outer rotor, it is investigated how the suction pressure recess can change the force acting on the outer rotor. The actual internal gear pump without the suction pressure recess has a large friction torque, and it corresponds to a large force on the outer rotor, which is calculated from the pressure distributions on the inside and outside of the outer rotor. In addition, on the basis of the measured friction torque of the test pump and the force acting on the outer rotor, calculated using the results of the pressure distribution, the coefficient of friction between the outer rotor circumference and the body can be estimated.

Prestall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation

Computational fluid dynamics calculations using high-performance parallel computing were conducted to simulate the prestall flow of a transonic compressor stage, NASA compressor Stage 35. The simulations were run with a full-annulus grid that models the 3D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation demonstrates the development of the rotating stall from the growth of instabilities. Pressure rise performance and pressure traces are compared with published experimental data before the study of flow evolution prior to the rotating stall. Spatial fast Fourier transform analysis of the flow indicates a rotating long-length disturbance of one rotor circumference, which is followed by a spike-type breakdown. The analysis also links the long-length wave disturbance with the initiation of the spike inception. The spike instabilities occur when the trajectory of the tip clearance flow becomes perpendicular to the axial direction. When approaching stall, the passage shock changes from a single oblique shock to a dual shock, which distorts the perpendicular trajectory of the tip clearance vortex but shows no evidence of flow separation that may contribute to stall.

Enhancement of rotordynamic performance of high-speed micro-rotors for power MEMS applications by precision deep reactive ion etching

High-precision fabrication is indispensable for high-speed silicon micro-rotors for power MEMS applications so as to minimize the rotor imbalance that deteriorates the rotor performance. Etch variation of deep reactive ion etch (DRIE) process results in differences in rotor blade heights and thus rotor imbalance. A Fourier transform of the etch non-uniformity along the rotor circumference revealed the global etch variation across the wafer and local variations in etch rates depending on the concentration or proximity of the patterned geometry. Rotor imbalance arising from the global etch variation of DRIE process was estimated, which compared favorably to results obtained from spinning experiments. The global etch non-uniformity which culminates in rotor imbalance could be alleviated to 0.25% across a rotor of 4.2 mm diameter by optimizing the plasma chamber pressure. The developed DRIE recipe successfully reduced the rotor imbalance and thus enhanced the rotordynamic performance. The manufacturing processes presented herein are readily applicable to the constructions of other microstructures containing intricate geometries and large etched areas.

Structural Design Measures to Suppress Fluid Noises of Large Capacity Open Type Motors

This paper presents structural design measures to suppress fluid noises of large capacity open motors at their generation stages without any silencers. Interaction noise, which has high peaks at certain frequencies, is largely reduced by as much as 5dB (A) in the overall noise level by nonuniform distribution of the rotor radial vent openings along the rotor circumference. Turbulent noise, which appears in a wide frequency range, is significantly lowered by as much as 6dB (A) in the overall noise level by unaligning the rotor radial ducts with respect to the stator radial ducts by a vent width. These two structural design contribute to reduce the size of large capacity open motors as small as 1/3 compared to the conventional motors.

Fancy-yarn Formation in Rotor Spinning by a Combination of Excess-material Feedingand Pressurized-air Injection

Methods for producing fancy yarns on rotor-spinning machines are well known. The most commonly used are methods which feed excess material to the rotor. One disadvantage with this principle is that effects shorter than the rotor circumference cannot be achieved. By combining excess feeding of material with blowing of pressurized air into the fibre-transport channel, it became possible to divide long effects into short ones of variable length, thus creating new types of fancy yarns.

Analysis of Leakage Flow through Clearance on Rotor Face in Vane Compressors.

The performance of compressors used for automotive air conditioners is affected greatly by leakage which flows through a clearance between a rotor face and a sideplate. There are some studies which analyze distributions of pressure and velocity on the rotor face under a certain boundary pressure distribution on the rotor circumference. In this study we analyzed the leakage flow through the clearance on the rotor face by using a more realistic boundary condition which considers that pressure on the rotor circumference changes periodically with rotation of the rotor. Because of less influence of inertial force than that of viscous force, the pressure and velocity distribution at each moment can be evaluated under a quasi-steady condition with an instantaneous pressure distribution on the rotor circumference. On the other hand, the average flow field on the rotor face must be analyzed under a boundary condition that pressure at each angular position on the rotor circumference is equal to the time average of pressure in a compression chamber which is facing that position.

An air-supported polarizer rotator with precise phase control for LF modulation of optical and infrared radiation

A high precision rotator with accurate mechanical phase control has been constructed. The system is primarily designed for the rotation of polarizers, diameters up to 100 mm, to produce amplitude modulation of broad band radiation in acousto-optical instruments for radiation intensity measurement. Rotation speed may be phase-locked at 2, 4 or 8 Hz to a crystal oscillator or over the range 0.625-10.5 Hz to an external signal. Air bearings are used for low friction and noise: acoustic output, at 80 mm, is only 16 mu Pa at 4 and 8 Hz. A high torque motor gives fast rotor acceleration, 57 rad s-2, and broad-band phase control electronics (analogue and digital) utilizing encoding marks on the rotor circumference give good stability over the range of speeds without external adjustment. Outputs at 128 and 4 pulses rev-1 are provided for synchronization of external apparatus such as phase sensitive detectors. The standard deviation, at 4 Hz (240 RPM), in phase determined between pi /2 pulses (4 per rev) is 1 mrad and in frequency, measured over 100 s, is 0.8 mu Hz (2*10-7).

Flow Visualization of the Motions of Elastomers and Molten Plastics in an Internal Mixer

Abstract A basic study of flow visualization of motions of elastomers in a model internal mixer with Banbury rotors has been presented. The behavior of butadienestyrene copolymers (SBR), cis-polybutadiene (BR), natural rubber (NR), and various molten plastics has been investigated. The SBR's and BR behave similarly, exhibiting tearing when stretched by the moving rotor tip away from the bridge in the mixer. This results in large stagnant regions between the bridge and ram in the mixer. The NR does not tear but stretches out when the rotor tip pulls it around the rotor circumference. At low fill factors, the NR bands about the rotors. Studies of molten plastics including low density, high density polyethylene and polystyrene are also reported. Longitudinal motions of rubber on the rotors have been investigated.