Dynamics of a powered disk in clay soil

To investigate the performance of engine cooling water pump in automobile with variable rotating speed, experimental tests and numerical simulation are carried out on an engine cooling water pump under the rotating speed of 2650, 2960, 3700, and 4300 r/min. The hydraulic performance under 3700 r/min rotating speed and the cavitation performance under 340 L/min flow rate are tested and analyzed. The predicted results agree well with the experimental results, indicating that the simulation has high accuracy. The results show that the head of engine cooling water pump increases gradually and the best-effective region moves toward high flow rate condition with the increase in rotating speed. The augment of rotating speed would deteriorate the internal flow fields and causes more energy losses, which is due to the increase in tip leakage flow and enhancement of rotor–stator interaction effects. And, the rotor–stator interaction effect is sensitive to the temperature under various rotating speeds. Furthermore, the required net positive suction head increases with the increase in rotational speed and anti-cavitation performance is weakened during cavitation conditions.

In this article, a numerical investigation was performed on a quadrotor UAV propeller with the aim of examining effects of airspeed and rotational speed on thrust coefficient, which is one of the most important parameters on propeller aerodynamic performance. In that purpose, Computational Fluid Dynamics (CFD) analyses of an 11-inch propeller were carried out at different airspeeds and rotational speeds in vertical climbing flight condition. In order to have optimum number of mesh elements in computational domain, mesh independence analyses were also conducted. In conclusion, results of the analyses with k-ω SST turbulence model were shown that, increase in rotational speed was leaded to higher turbulent kinetic energy. Furthermore, higher rotational speeds also resulted in higher differences between numerical estimations and experimental data, but found to become more independent from airspeed.

The paper presents the numerical investigation results of the gyroscopic moments’ influence on the dynamic behavior of a transmission shaft, specifically on the change in its natural oscillation frequencies with varying rotational speeds and direction. Systems that include shafts are often operated at different rotational speeds. If a shaft is represented as an elastic rod, it can perform natural and forced oscillations. The natural frequencies of the shaft depend on its rotational speed. This behavior is caused by precession motion. Therefore, the oscillatory motion of the shaft is considered in space, accounting for gyroscopic and other inertial forces. As a result, the dependences of the natural oscillation frequencies in the inertial and rotating coordinate systems, plotted using developed software for studying the dynamics of elastic shafts, are shown. The numerical values of the natural oscillation frequencies for an unmoved shaft and its critical rotational speeds for direct and reverse precession are also presented. An analysis of the results and conclusions regarding the possibility of operating the shaft in certain frequency ranges have been made. It is noted that the natural frequencies of elastic shafts during rotation are dependent on the influence of gyroscopic moments. An important parameter is the natural oscillation frequency in the rotating coordinate system, as it is directly related to the elastic body. As the diagrams show, the change in the natural frequency in the rotating and inertial coordinate systems occurs with different intensity when the rotational frequency changes: slowly in the inertial system and rapidly in the rotational system. In addition, when the rotational speed increases in the range up to critical values, the natural oscillation frequency in the rotating coordinate system decreases. With a further increase in rotational speed beyond the critical value, the natural oscillation frequency begins to grow, and the precession movement occurs in the reverse direction.

The purification of BSA from yeast/BSA binary suspension using batchwise centrifugal filtration under various conditions is studied. Effects of suspension pH and rotational speed on the cake properties, filtration rate and protein recovery are discussed. The experimental results indicate that the filtration rate is significantly affected by the cake growth at the initial periods of filtration, and no evident rate difference can be found among different suspension pH values under a low rotational speed. However, the effect of cake compression becomes more dominant as rotational speed increases. The compression of yeast cake is irreversible and strongly affected by the suspension pH especially under a high rotational speed. The cakes formed at pH 3.0 possess the highest compressibility due to the yeast coagulation, while the average specific resistance of cake is the lowest at pH 7.0 because of the high zeta potential of yeast cells. In addition, the recovery of BSA can be as high as 95–98% under the operating conditions of this study. Since the BSA concentration in the filtrate keeps constant during the filtration under various rotational speeds, the recovery of BSA is dependent solely on the filtration rate in spite of the little adsorbed amount on the yeast cells. To operate under higher rotational speed and pH 7.0 is optimal from the viewpoint of economic operation time and protein recovery.

Microstructure and mechanical characterization of continuous drive friction welded grade 2 seamless titanium tubes at different rotational speeds

In order to avoid the high cycle fatigue which leads to the failure of turbine blades, friction structural damping has been widely used in turbine blade designs to reduce vibratory stresses by energy dissipation. A method is developed here to analyze the influence of friction structural damping on the vibration characteristics of turbine blades. Vibratory responses of a long steam turbine blade with shroud and snubber are studied. Finite element contact analysis of the steam turbine blades which are modeled in 3-D solid elements is conducted to obtain the normal contact force on the shroud contact surface and snubber contact surface of adjacent blades under five different rotational speeds (2100rpm, 2200rpm, 2413rpm, 2600rpm and 3000rpm). A rig for the tests of non-rotating turbine blade with friction damping structure is built. The normal contact forces of the shroud and snubber are applied to the blade according to numerical results. The response curves and modal damping ratios of the blade under different normal contact forces, which each one is related to a different rotational speed, are obtained. The experimental results show that with increases in rotational speed, modal damping ratio of the blade experiences an increasing period followed by a decreasing period while the resonance amplitude decreases first and then increases when there is only shroud contact. The effects are similar when there are both shroud and snubber contact. The modal damping ratio of the blade is basically identical with that of the uncoupled blade for the rotational speed above 2600rpm. For this range of rotational speed, the resonance frequency increases with the increase of rotational speed, and the changes of the resonance frequency are very trivial.

Rotating electrodes can effectively improve the processing performance of micro-electrical discharge machining (micro-EDM), but there is still a lack of systematic research on the specific effects of electrode rotation and rotational speed changes. In this paper, the effects of electrode rotation and rotational speed on the discharge channel, debris stress, and debris motion in micro-EDM were analyzed theoretically. An AISI304 sheet was used as the workpiece and helical tungsten carbide alloy as the electrode. The through-hole drilling experiments of micro-EDM were carried out at low and high discharge energy and different electrode rotational speeds. In terms of processing efficiency, the effects of electrode rotation and rotational speed on material removal rate (MRR), relative tool wear ratio (RTWR), and short circuit number were analyzed. The results show that MRR increases first and then decreases, RTWR and short circuit number decrease first and then increase. In the aspect of processing precision, the impacts of electrode rotation and rotational speed on taper angle and overcut were analyzed. The results show that the electrode rotational speed has little effect on the change of the taper angle. In addition, when the electrode rotational speed is small, there is no obvious change in overcut. When the speed is too high, the overcut increases obviously and shows a trend of continuous increase. Finally, by comparing the experimental results, the optimal electrode rotational speeds of micro-EDM with two kinds of discharge energy were determined. The final experimental results also verify the correctness of the previous theoretical analysis.

Band formation (axial segregation) and subsequent coarsening of bidisperse mixtures in long circular tumblers is well documented for the case where the cylinder is at a single fill level and the interstitial fluid is air. However, little information is available for a range of fill levels, nor is the effect of rotational speed on segregation clear. Moreover just a handful of studies have focused on slurry systems, where the interstitial fluid is a liquid. This is precisely the parameter space covered in this study. Experiments are conducted using a 2:1 mixture of 882 and 272 mum glass beads with water as the interstitial fluid. Several different phenomena are uncovered. Results indicate that bands are less likely to form at low rotational speeds and low fill levels. As the fill level and rotational speed increase, more bands form and they form more quickly. However, at fill levels near 50% and high rotational speeds the bands contain a mixture of particles rather than being relatively pure. Furthermore, the evolution of the core of small beads that forms deep in the bed depends on the fill level and the rotational speed. For certain fill levels and rotational speeds, the core remains prominent as bands form, while in other cases the core disappears entirely between bands. Finally, when the tumbler is tilted so that the fill level varies from 14% at one end to slightly more than half full at the other end, the bands and core that form locally qualitatively correspond with those that would form for the corresponding fill level in a horizontal cylinder.

The two phase program addresses long-term developments in deep well and hard rock drilling. TerraTek believes that significant improvements in drilling deep hard rock will be obtained by applying ultra-high rotational speeds (greater than 10,000 rpm). The work includes a feasibility of concept research effort aimed at development that will ultimately result in the ability to reliably drill ''faster and deeper'' possibly with smaller, more mobile rigs. The principle focus is on demonstration testing of diamond bits rotating at speeds in excess of 10,000 rpm to achieve high rate of penetration (ROP) rock cutting with substantially lower inputs of energy and loads. The significance of the ultra-high rotary speed drilling system is the ability to drill into rock at very low weights on bit and possibly lower energy levels. The drilling and coring industry today does not practice this technology. The highest rotary speed systems in oil field and mining drilling and coring today run less than 10,000 rpm--usually well below 5,000 rpm. This document details the progress to date on the program entitled ''Smaller Footprint Drilling System for Deep and Hard Rock Environments: Feasibility of Ultra-High-Speed Diamond Drilling'' for the period starting 1 October 2004 through 30 September 2005. Additionally, research activity from 1 October 2005 through 28 February 2006 is included in this report: (1) TerraTek reviewed applicable literature and documentation and convened a project kick-off meeting with Industry Advisors in attendance. (2) TerraTek designed and planned Phase I bench scale experiments. Some difficulties continue in obtaining ultra-high speed motors. Improvements have been made to the loading mechanism and the rotational speed monitoring instrumentation. New drill bit designs have been provided to vendors for production. A more consistent product is required to minimize the differences in bit performance. A test matrix for the final core bit testing program has been completed. (3) TerraTek is progressing through Task 3 ''Small-scale cutting performance tests''. (4) Significant testing has been performed on nine different rocks. (5) Bit balling has been observed on some rock and seems to be more pronounces at higher rotational speeds. (6) Preliminary analysis of data has been completed and indicates that decreased specific energy is required as the rotational speed increases (Task 4). This data analysis has been used to direct the efforts of the final testing for Phase I (Task 5). (7) Technology transfer (Task 6) has begun with technical presentations to the industry (see Judzis).

We studied the influence of the rotational speed and eccentricity of the ring image on the severity of the stereokinetic effect (SE) in a group of 36 children aged 8 to 16 years with partial optic atrophy and in the control group of 44 age-matched children with a normal fundus. Four variants of the ring image with the eccentricity of 0.2, 0.4, 0.6 or 0.8 were used as a test image. The rotational speed of the ring image was 2, 10, 30, 60 or 90 rpm. It was found that the stereokinetic effect was absent in the majority of children (63.9%) with optic atrophy at a combination of eccentricity of 0.2 and a rotational speed of 2 rpm, in contrast to the control group, where the stereokinetic effect was only absent in 9.1% of children under the same conditions of stimulus presentation. The stereokinetic effect was observed with all eccentricities when the speed of rotation of the test image was 30–90 rpm in children with optic atrophy and 10–90 rpm in children from the control group. The number of children with alternate perception of the virtual cone and the virtual funnel was significantly higher in the control group than in the group of children with optic atrophy at all the test image eccentricities and rotational speeds used. The binocular figure size estimates were equal to the monocular estimates in the group of children with optic atrophy for all the image eccentricities and rotation speeds in contrast to the control group with a general tendency for the virtual cone size estimate to increase under the monocular conditions of observation. An increase in the test image rotation speed from 2 to 60 rpm was accompanied by an increase in the size of a virtual figure and a significant decrease in the duration of alternate dominance of virtual cone and virtual funnel perception in both groups of subjects with all the eccentricities used. The difference between the results obtained in the group of children with POA and in the control group may be explained by reduction of afferent visual information flow. These differences are partially offset by increased speed and increased eccentricity of the test image.

Application of thermoplastic materials has increased dramatically in recent decades due to its recyclability, low density, resistance to chemical changes. The friction stir welding process is one of the new methods of solid state welding, which has recently undergone significant improvement. In this research, using a new tool Made of plain carbon steel st37 in friction stir welding and low cost turning machine, composite sheets of thermoplastic polymer base have 12% continuous carbon fiber in the form of buttocks with two rotational speeds of 250 and 355 rpm and two advance speeds of 5/6 and 9 mm/min Optical microscope images (OM) showed the complete connection of materials. Increasing the inlet temperature resulted in the formation and growth of cavities and converting them into tunnel cavities. In general, the parameters affecting the connection quality in this study included the main shoulder diameter and rotational speed, so that, based on the results of scanning electron microscopy (SEM), the increase in rotational speed resulted in the grinding of continuous carbon fibers and thus increased tensile strength. The results of the tensile test showed that the failure of the samples is due to microstructural changes in the HAZ, in the joint zone of the welding zone and the base materials. According to the results, it can be said that using this new tool in the friction stir welding method, because of the reduction of rotational speed compared to previous studies and the lack of use of a multi-axial milling machine, can save energy.

Microstructure and mechanical properties of alumina-6061 aluminum alloy joined by friction welding

A test stand to determine the performance of a dynamic-static rotor separator is described. An experimental study has been conducted of the separator at different air flow rate and rotor rotating speeds with pulverized coal serving as a raw material. Experimental results indicate that either an increase of the rotor rotating speed or a decrease of the air flow rate can increase the fineness of the pulverized coal at the outlet of the separator, whose value of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">45</sub> can be as low as 0. As the rotor rotating speed increases, the comprehensive separation efficiency decreases in general, but it fluctuates at high rotational speed. The comprehensive separation efficiency rises as the air flow rate increases. In gas-solid two-phase flow, there is the minimum pressure drop as the rotational speed increases and the pressure drop has an accelerative increase as the air flow rate increases.

The purpose of this article is to evaluate the impact of air film thickness and chamber shape on the performance characteristics of an aerostatic thrust bearing operating at ultra-high rotational speeds, including pressure distribution, mass flow rate, load capacity, and stiffness. A three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis using the SST-kω model is employed to study the effect of supply pressure on various operational and geometric parameters. A comparison between the numerical simulation and experimental data was conducted for chamber shape A to verify the model's robustness. Both approaches demonstrated good agreement. Pressure distribution and mass flow were examined across different chamber geometries, revealing the presence of inertia effects and gas vortices, which diminish as the air film thickness increases. Further investigation showed that the load capacity of the aerostatic thrust bearing decreases slightly as the rotational speed increases. Additionally, the numerical results indicate significant variations in the performance of the aerostatic thrust bearing depending on the geometry of the orifice chamber.

Cadmium sulfide thin films have been prepared by sol-gel spin coating method on glass substrates at different rotational speeds. Glancing angle X-ray diffraction patterns of CdS thin films exhibit cubic phase with (1 1 1) as preferential orientation. The surface morphology of the CdS thin films was studied by atomic force microscope. The electrical resistivity of CdS thin films decreased from 5.66 × 10³ to 1.72 × 10³ Ω.cm with the increase of rotational speed from 1500 to 3000 rpm. The optical transmittance of CdS thin films increased because of reduction in film thickness with the increase of rotational speed. The optical band gap of CdS thin films decreased from 2.65 to 2.46 eV with the increase of rotational speed due to quantum confinement effect. The normal dispersion of refractive index for CdS thin films is described using Wemple-DiDomenico single-oscillator model. The optical dispersion parameters such as single-oscillator energy (E_o), the dispersion energy (E_d) and the static refractive index n_o were calculated. The Verdet coefficient (V) is determined based on the refractive index dispersion study. The first and third order nonlinear optical susceptibility (χ⁽¹⁾, χ⁽³⁾), nonlinear refractive index (n₂) are determined for CdS thin films.<div><br></div>