Increase In Rotational Speed Research Articles

Effect of Different Rotational Speeds on Graphene-Wrapped SiC Core-Shell Nanoparticles in Wet Milling Medium.

The effects of the wet milling rotating speed on the number of graphene layers and graphene quality, and the conversion efficiency of graphite exfoliate to graphene, were investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results show that the number of few-layer graphene nanometer sheets (GNSs) (≤10 layers) gradually increases with the increase of rotational speed in the range of 160–240 rpm. The proportion of GNSs with 0–10 layers reaches more than 80% as the rotational speed is increased to 280 rpm. GNS defect types in the composite materials are marginal defects with minimal influence and almost no oxidation. In the range of 160–280 rpm, the intensity of graphite peak decreases and the conversion efficiency of graphene increases with the increase of rotational speed. This is the same as the experimental result obtained by HRTEM.

Experimental Study on Behavior of Coolants, Particularly the Oil-Cooling Method, in Electric Vehicle Motors Using Hairpin Winding

This paper analyzes the characteristics of oil behavior in the oil-cooling of motors with hairpin winding to understand how to maximize cooling performance. The oil cooling is performed by directly spraying oil onto the motor components. The results show that as the temperature of the oil increases, the viscosity decreases, and the oil film is formed more evenly; however, oil splashing also increases. Similarly, as the flow rate increases, oil splashing also increases, but the amount of oil forming the oil film increases. However, the oil film is not affected by the rotor’s rotation. In contrast, the immersed oil is found to be closely related to the rotor’s rotation. As the rotational speed increases, the immersion oil is mixed with the air, and oil churning occurs. The mixing phenomenon increases as the temperature and flow rate of the oil increases. The higher the oil level, the greater the oil churning. As the oil is mixed with air, the heat transfer coefficient decreases, which adversely affects the thermal management of the motor. As a result, when considering the oil film and the immersion oil, the optimal oil temperature, flow rate, and oil level are at 60 °C, 0.140 kg/s, and 85 mm, respectively. The results of this paper give important information about EV motor cooling and can contribute to the development of high-performance motors.

Effect of Turbulent Fluctuation on Settling Behavior of Dredged Slurry in Sheared Condition

For the land shortage problem upon the city development in coastal areas, it is of great importance to improve the overall understanding of the settlement behavior of dredged slurry and determine the required site water storage capacity as well as the mechanical properties of the newly formed dredged slurry. This paper presents an experimental investigation on the effect of turbulent fluctuation on the settling behavior of dredged slurry in sheared condition via a self-developed testing apparatus namely double cylinder settling column. Test results showed that the settling velocity of the soil-water interface initially increased then decreased with the increasing rotation speed of the inner column. The interface would disappear and a stable suspended layer was observed when the rotation speed was greater than 20 rad/min, where water contents and grain composition were not changed over the depth. The particle content was closer to that of the original sample as the rotation speed kept increasing in the suspended layer. It was found that the stabilized flocs were gradually broken down by the turbulence effect existing in the sheared slurry. Moreover, the stabilized flocs were losing the stability gradually as the flowing velocity increased till 10 rad/min and the floc structure was broken down completely once the flowing velocity was greater than 20 rad/min.

Studying The Influence of Rotor Speed and Diameter on The Proprties of Combed Rotor Spun Yarn.(Dept.T)

In this work the influence of sliver preparation has been investigated with rotor speed and diameter. Three yarn counts (medium range) were produced, using carded and combed sliver. Each yarn was produced at three levels of rotor speed and two levels of rotor diameter. Properties of the produced yarns were examined. Results show that, increasing rotor speed deteriorates yarn regularity, strength, elongation and imperfections of combed yarns. Increasing rotor diameter reduced number of thin places. It also improved regularity of combed yans.

Effect of a cooling method on the structural and mechanical properties of friction stir spot welding with a 2524 aluminum alloy

Friction stir spot welding (FSSW) is a clean, environmentally-friendly and cost-effective welding technology. To weld joints with improved mechanical properties, an FSSW experiment with a 2 mm-thick 2524 aluminum alloy sheet was performed to explore the influence of ambient cooling (AC), forced air cooling (FAC), waterflow cooling (WC), and an increasing rotational speed under WC, and to evaluate the welding method with regard to the resulting structural and tensile properties of the joint. The results showed that cooling-assisted welding reduced the width of the heat-affected zone (HAZ) and marginally increased the microhardness of the welding nugget zone (WNZ). The maximum tensile shear load (L) and effective width (W) values were 4673 N and 1958 μm at FAC, respectively, which were higher than the values of 4296 N and 1763 μm found with AC, respectively; in addition, the minimum values were 2946 N and 948 μm with WC, respectively. These results are not consistent with the idea that the joint strength can typically be improved with WC, because water absorbs a large amount of welding heat and reduces the plastic deformation capacity of the structure, thereby decreasing the W and L of the joint. Increasing the rotation speed of the welding tool can increase the heat input, which requires increasing the rotation speed along with WC. L and W reach their maximum values of 7652 N and 3320 μm, respectively, at 2500 r·min−1. As the rotation speed increases, L and W decrease. All joints underwent ductile fracturing, and the dispersion distribution of the second-phase particles at the bottom of the dimple exhibited good performance.

Some investigative studies on dissimilar metals by friction stir welding

The aim of the current work is to develop weldments and to investigate the microstructure and mechanical properties of the aluminium alloy 6061-T6 and magnesium alloy AE42 plates (120x100x3 mm) which are welded through FSW. H13 conical thread tool pin was selected to prepare the welded joints. Two plates that were co-ordinated vertically according to the welding directions were well joined. In this study, two parameters such as weld speed at 60,150 mm / min and tool rotation speed at 800, 1200 RPM are taken into account as defect free. By changing these parameters similar and dissimilar alloys are welded together. Tensile specimens (according to ASTM standards) were developed to estimate mechanical properties including tensile strength, % elongation, yield s trength and joint efficiency. It was found that an increase in the tool rotational speed or welding speed of the tool led to an increase in the tensile strength, which reached a maximum value and then decreased. (LOM) Light optical Microscopy research was accustomed examine and study the weld zone properties. Dynamic recrystallization was discovered within the weld region in addition as within the thermo-mechanical heat-affected zone (TMAZ). There’s a transparent reduction within the quantity of precipitate through the TMAZ and from the BM (Base Material) into the weld zone. Observed precipitates from similar and dissimilar welded joints -Mg2Si, Al2O3, SiC, Mg17Al12, Mg2Al3, Al11Ce3 and Al2Ce. Welds are without porosity. XRD with the EDS characterization was executed in the NZ (Nugget Zone) demonstrated the existence of SEM intermetallic phases and their weight in percent. Rapid phase structures of welded joints were detected using X-ray diffraction (XRD), however, the SEM fractograph indicated a flexible ductile fracture mechanism. Vickers micro-hardness test was performed on the thickness of the plate within the weld space to review and perceive the variation of hardness with thickness. An interrelationship between size of precipitate and micro hardness was ascertained. The corrosion behaviour of the base alloy and welded joints was measured in 3.5% NaCl solution using the salt spray test and by investigating the corrosion parameters (corrosion rate, exposure time and weight reduction). Corroded products were analysed and classified using optical microscopy and SEM. The corrosion rate decreases with increasing exposure time, but remains uniform as the corrosion time increases. Finally, a three-dimensional finite element phases was developed for temperature evolution in the friction-stir welded joint plunge depth, dwell, moving phases, and the heat conduction effect is arbitrary in the LAGARAGIAN-EULERIAN formulation in the ABAQUS / EXPLICIT, Johnson-Cook (JC) elastic-plastic model Will be used. The JC model defines the strength of the material as a function of three parameters, i.e. the strength of the material depends on the strain hardening effects, strain rate effects and temperature and verifies the s imulated results with the experimental results.

Influence of operational parameters on the recovery rate of polyester resin surface of locally designed drum oil skimmer

The development in the industry makes the process of transferring oil between countries a necessity. There has been massive pollution in the rivers environment resulting from the leakage of oil from oil ships, the transfer of factories and workshops wastes to rivers, which posed a great danger to human life and living creatures. Therefore, it is necessary to direct attention to save the aquatic environment from pollution as the process of collecting oil manually is insufficient and slow. In the present study, the drum skimmer is manufactured with a polyester resin surface. This material is characterized by its adhesive effectiveness to liquids and availability. Operational parameters such as viscosity, temperature, and drum rotation speed are investigated using designed and fabricated drum skimmer. The experimental results showed that the fluid viscosity has a high effect on the recovery rate. Also, the recovery rate increases as the drum rotation speed increase. Moreover, the best improvement in the recovery rate is obtained at the maximum temperature.

Thermal-mechanical fully coupled analysis of high-speed angular contact ball bearings

The thermal and mechanical properties of angular contact ball bearings are critical to their operating accuracy and service life. On the basis of the theory of dynamics and frictional heat generation, this work establishes a thermal-mechanical fully coupled model. The high-speed motion characteristics, temperature, and dynamic stiffness are analyzed, and the simulation results are compared with the theoretical calculation and experimental results. Then, the temperature and axial deformation of the bearings under different rotation speeds are analyzed, and the laws of mechanical and thermal characteristics of the bearings are obtained. Results show that an increase in the rotation speed of the inner ring causes the temperature of each component to increase, with the contact area of the balls showing the greatest increase in temperature. An increase in rotation speed also increases the axial deformation of the inner ring.

Influence of engineering parameters on rock breaking performance of raise boring machine

As a crucial rock crushing equipment, the raise boring machine (RBM) has been widely used in underground engineering construction, especially in the construction of shaft wellbores. Herein, experiments and measurements were carried out in a hydropower station construction project. By loading a set of engineering parameters, data from the four parameters of pulling force, torque, rotation speed and drilling speed of the drill pipe were obtained. The research results show that torque in the rock breaking process has no correlation with the rotation speed and is linearly related to the pulling force. Increasing rotation speed or pulling force can both clearly improve rock breaking efficiency; however the effect from pulling force is greater. This experimental method is able to find the best engineering parameters so that the RBM can obtain minimum energy consumption for rock breaking.

Loading Performance of a Novel Shearer Drum Applied to Thin Coal Seams

The poor loading performance of shearer drums restricts the development and production efficiency of coal in thin coal seams. Changing operation and structural parameters can improve the drum’s loading performance to some extent, but the effect is not obvious. A two-segment differential rotational speed drum (TDRSD) was proposed after analyzing the drum’s influence mechanism on coal particles. To further reveal the drum’s coal loading principle, the velocity, particles distribution, and loading rate were analyzed. The effect of the matching relationship of the rotational speed and helix angle between the front and rear drum are also discussed. The results show that a lower front drum rotational speed had a positive impact on improving the loading performance, and the loading rate first increases and then decreases with the increase in rear drum rotational speed. The optimal loading performance was obtained in the range 60–67.5 rpm. The front drum’s helix angle had no evident effect on loading performance, and the loading rate increase with the increase in the rear drum’s helix angle. The results provide a reference and guidance for operation parameters selection, structure design, and drum optimization.

Experimental study on the lubrication characteristics of water-lubricated rubber bearings at high rotating speeds

A test rig is designed to study the lubrication characteristics of water-lubricated rubber bearings. The film pressure signal quality is improved by installing signal conditioners inside the hollow shaft. Four triaxial force sensors are adopted to measure the bearing load in two directions simultaneously. The experimental results show that the film pressure drops rapidly downstream of the minimum clearance. The water film can bear a certain negative pressure without cavitation. As the rotating speed increases, the valley value of the film pressure decreases, and the peak value increases. The increase of water supply pressure improves the hydrostatic pressure, thereby, the film pressure rises over the whole circumference. Different from the laminar flow, the bearing load increases faster as the rotating speed increases, indicating a turbulent flow at high rotating speeds.

Formability and mechanical property of refill friction stir spot–welded joints

The effects of rotation speed and plunge depth on macro/microstructures and mechanical properties of dissimilar 2195/2219 aluminum alloy joints produced by refill friction stir spot welding (RFSSW) were investigated. The results show that some shallow annular grooves present on the joint surfaces depending on the process parameters. Besides, hook defects are in the form of downward bending due to the higher strength of 2195 aluminum alloy. The change of rotating speed has no apparent influence on hook defect, while the increase of plunge depth makes the height of the hook defect increase significantly. The higher tensile-shear strength is associated with increased rotation speed. However, as the plunge depth increases, the tensile-shear strength rises first and then decreases. The highest tensile-shear strength measured is 6480 N, for a rotation speed of 1600 rpm, and plunge depth of 2.5 mm. Besides, there are two kinds of fracture modes present: the plug fracture and the shear-plug fracture.

Experimental Research on the Influence of Working Conditions on Vibration and Temperature Rise of Si3N4 Full‐Ceramic Bearing Motors

Working conditions such as lubrication, preload, and rotational speed have important influence on vibration and temperature rise of the spindle motor. In this study, controlled variable experiments are carried out on the silicon nitride (Si3N4) full‐ceramic ball bearing and steel bearing of the same type, and the vibration signal characteristics and temperature rise of the spindle motor are tested and analysed, by changing the lubrication conditions, preloads, and rotational speeds of the spindle motor. Through the research, it is found that as the rotational speed increases, the vibration velocity of the Si3N4 full‐ceramic bearing spindle motor under different preloads and lubrication conditions shows an overall increasing trend; kurtosis generally presents a downward trend and gradually flattens, indicating that although the vibration velocity increases at high speeds, the vibration signal shows a relatively stable state. As the rotational speed increases, the difference of vibration velocity under the condition of applying preload and no preload decreases, indicating that the influence of preload on the vibration of full‐ceramic bearing spindle motor decreases with the increase in rotational speeds. At the same time, it is found that fr and 5fr have greater impact on the vibration of full‐ceramic bearing spindle motor, where fr is the frequency of the bearing in normal operation, and 5fr is 5 times of the normal operating frequency. Lubrication conditions have little effect on the temperature rise of full‐ceramic bearing spindle motor, and the temperature rise under nonlubricated conditions is even slightly lower than that under grease lubrication conditions. The research results show that the vibration velocity and temperature rise of Si3N4 full‐ceramic bearing spindle motor are less than those of steel bearing with the same type, indicating that full‐ceramic bearing has better performance than steel bearing under the same working conditions.

The effect of rotation speed and mixer size on granular flow and mixing in bladed mixers

Bladed mixers are widely used in the industry for granular mixing. In the past decades, the mixing of particles in bladed mixers has been extensively investigated experimentally and numerically. Recently, GPU-based DEM has been employed to simulate various industrial-scale applications. This work aims to apply the GPU-based DEM to investigate the effect of rotation speed and mixer size on granular mixing in bladed mixers of different sizes. The simulation in a larger mixer revealed distinct particle flow patterns that well-describe the mixing mechanism which is difficult to observe in a smaller mixer. The Lacey’s mixing index curves revealed a delay in mixing as the mixer size increases. The mixing rate decreases as the mixer size increases and it can be improved with increasing rotation speed. The average particle velocity increase significantly with increasing rotation speed and mixer size.

Production of recycled EPS fibers by centrifugal spinning

Centrifugal spinning is a new technique for producing of nano and microfibers that has a great differential: a higher production rate than those presented by traditional methods. Due to a great interest in using nano and microfibers in technological applications along with the environmental interest in polymer recycling, this research had the purpose of production fibers by centrifugal spinning from the expanded poly-styrene recycling and the evaluation of the influence of operational parameters such as the concentration of polymer solution and the speed of rotation in the average diameter and in the distribution of the diameters of fibers formed. The fibers obtained were characterized using the Scanning Electronic Microscopy (SEM) and they had their diameters measured using ImageJ software. The fibers obtained in this research were entangled, woven, fused, with a rough and porous surface, with bead formation and without directional ordering. The results obtained show that the polymer solution concentration was the most influential parameter in the fibers analyzed characteristics and, in general, its increase generates an increase in the average diameter. With the increase in rotation speed, there has been often a reduction in the presence of beads and microparticles due to the better stretching of the fibers. In less concentrated solutions, continuous fibers with more regular surfaces were obtained, however, promoting the higher production of beads. In the most concentrated solutions, we noticed the formation of porous fibers and very rough surfaces, as well as fused and woven fibers. Through the measurement of its diameters, it was possible to observe the obtaining of fibers with average diameters of 407,02 nm to 38113,20 nm, and the smallest value was obtained with the parameters of 5% w/w of polymer concentration and rotation speed of 15000 rpm and the highest value had 15% w/w concentration polymer and 10000 rpm.

Agro-Residues for Clean Electricity: In-Lab Trial of Power Generation from Blended Cocoa-Kolanut Wastes

As a way of waste-to-voltage conversion, a laboratory-based test trial of electricity generation from a blend of cocoa and kola nut harvest by-products is presented in this study. Bioethanol obtained from the blend through a process of fermentation is mixed with gasoline at specific proportions and employed to fire a spark-ignition engine that serves as a prime-mover in driving a four-pole three-phase salient-pole synchronous machine. Performance of the driving machine as the fuel-mix proportion and its speed of rotation varies is studied. Likewise, the electric power output characteristic of the driven machine operated at its rated synchronous speed is examined. It is found that the driving machine performs better on mixed fuel than on pure gasoline as the machine develops a gradual increase in mechanical torque and power as the proportion of ethanol in the fuel-mix and the rotational speed increases. While the highest values of torque and power developed on using pure gasoline are 12.4Nm and 2574W respectively at 1900rpm, 13.1Nm torque and 2953W power are obtained from the machine when powered with 10%-bioethanol fuel-mix at the same speed. Also, with 90V excitation voltage and rotation at 1500rpm synchronous speed, the driven machine continuously generates electricity at 207.6Vrms (line-to-line), 1.169A, 0.698pf, 48.17Hz, 0.294kW output. Therefore, this investigation shows that the availability of cocoa and kola nut harvest wastes could be explored as a steady source of biofuel for off-grid microgrid electrification at locations with such agricultural wastes advantages.

Production and Quality Evaluation of Young Thai Jasmine Rice Flake Using Drum Dryer

Immature rice grains contain high bioactive compounds. Drying has been used for the food preservation and reduction of agricultural waste. This study aimed to produce the rice flake from young Thai Jasmine rice grain (light green and soft texture) using double drum dryer at 120 °C, drum rotation speed 0.5, 0.7, and 0.9 rpm, and the ratios of grain to water of 1:3 1:5 and 1:7w/w. The nutritional properties of rice flake were also investigated. The results showed that increasing rotation speed gives a significant effect on the higher moisture content and water activity. Using lower water ratio with slowing down rotation speed resulted in higher brightness of the flake products including quicker dehydration. The selected optimal condition of preparing rice flake was 1:5 w/w young grain to water at 0.5 rpm drum speed. The flake contains fat, protein, carbohydrate, ash, approximately 0.004%, 6.140%, 88.686% and 0.92%, respectively. Phenolic content and antioxidant capacity of rice flake were decreased after drying. Total phenolic content of the flake was 280.931 mg GAE/g and antioxidant activities; DPPH, FRAP and ABTS were 254.158, 123.172 and 372.298 mg TE/g, respectively. Young rice flake remains a great nutritional value which has potential in the food industry.

МАГНИТНЫЕ СВОЙСТВА И ПОЛОСОВЫЕ ДОМЕНЫ В МИКРОПОЛОСКАХ PrDyFeCoB

The article provides the analysis of PrDyFeCoB magnetic microstripes prepared by extracting material from a melt on a rotating cooling disk. The phases 2-14-1, 1-4-1 and 1-2, α-FeСо were verified in the samples. The division of a hysteresis loop into two strands shows that the coercive field of the α-FeСо phase (500–700 Oe) determines the width of the hysteresis loop near the zero field, while the coercive field of the 2-14-1 phase (10 kOe) corresponds to lateral hysteresis loops. The saturation magnetization increases by 25% with an increase in the disk rotation speed by 3 times together with correspondent acceleration of the cooling rate. This is due to the increase in the proportion of the soft magnetic phase α-FeCo and the increase in the proportion of the amorphous phase with a decrease in the proportion of the main magnetic phase 2-14-1. Strip domains and their dynamics during magnetization were detected using Kerr magneto-optical microscopy.

Numerical calculation and experimental study on friction and lubrication of Stirling engine piston ring

To solve the practical problem of Stirling engine piston ring, numerical model on friction and lubrication were established based on average Reynolds equation theory. Numerical calculation results show: piston rings are in the mixed lubrication state which gas lubrication film and micro-convex body contact existing simultaneously; contact pressure is 2 orders of magnitude less than gas film pressure; contact pressure is approximately linearly related to mean gas pressure. Simulated test rig was built and experimental results show: high-pressure working gas leak to intermediate chamber through piston rings, and the pressure of intermediate chamber drops sharply at lowest pressure of circulation; piston ring wear increases when rotational speed or working pressure increase. The accuracy of numerical model was proved by experimental phenomena and test data.

Characteristics of Forces in Plane Polishing Based on the Magnetorheological Effect with Dynamic Magnetic Fields Formed by Rotating Magnetic Poles

Abstract Aiming at the process of magnetorheological (MR) polishing, we analyzed the characteristics of polishing forces (normal force [Fn] and tangential force [Ft]) in a machining process by using the Kistler 9171A 3-d rotating dynamometer. The influences of rotation speeds of magnetic poles and the workpiece, abrasive concentration, concentration of carbonyl iron powders, working gaps, and deflection distance of the workpiece on MR polishing forces with dynamic magnetic fields were investigated. The results showed that polishing forces of polishing pads with static magnetic fields were significantly attenuated. For MR polishing pads under a dynamic magnetic field, polishing force signals showed remarkable changes in dynamic stability. Polishing forces Fn and Ft decreased with the increased rotation speeds of the workpiece and working gaps, increased with concentrations of abrasives and carbonyl iron powders, and slightly increased with the deflection distance of the workpiece.