Influence Of Rotational Speed Research Articles

Effect of drilling pipe rotation on vortex induced vibration response of drilling riser

An experiment was carried out in a basin to investigate rotation of drilling pipe on vortex induced vibration response of drilling riser. Vibration displacement time-history and frequency are obtained. Results show that dominant vibration frequency in the in-line direction is almost twice as high as that in the cross-flow direction. The vibration amplitudes in both the cross-flow and in-line direction increase with an increase in rotation speed of drilling pipe under the experimental conditions. However, the influence of rotation speed drilling pipe on drilling riser vibration amplitude is insignificant. Dominant frequencies are invariant with variation of drilling pipe rotation under experimental conditions.

Influence of rotational speed on friction and wear properties of 35CrMo/GCr15 friction coupling

The effect of rotational speed on the friction and wear properties of 35CrMo/GCr15 was studied under the condition of boundary lubrication. The speed was set as 400r/min, 800 r/min, 1200r/min, 1600r/min, and the load were 200N. Working time was 120min. The ring block friction and wear testing machine were used for testing. The surface morphology changes of wear specimen were analyzed by scanning electron microscope (SEM). The results showed that the main form of the wear of the material was different with speed different. When the rotating speed was low, the wear was mainly abrasive wear, and the wear was mainly adhesive wear at high speed. When the speed was 800r/min, the wear rate was minimum, and the friction coefficient also was minimum. It shows that when the load was constant, the speed was too high or too low, would make the wear and tear intensified.

Evaluation and modeling of a spinning disc photoreactor for degradation of phenol: Impact of geometry modification

Abstract A new spinning disc photoreactor with two different designs employing baffles in its structure for degradation of phenol was studied and compared with conventional ones. TiO2 was successfully immobilized on stainless steel disc and Teflon baffles. X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy analysis were performed in order to give information on the crystal phase and structure of both TiO2 coatings and size of particles. The wettability of the photocatalyst film on the disc surface was evaluated by contact angle test. The results have demonstrated that complete phenol removal was achieved using baffles after 180 and 150 min of reaction time, which was 60 and 90 min faster than the reactor with smooth disc under optimum condition of the reactor (rotational speed = 290 rpm, flow rate = 2000 mL/min, disc diameter = 22 cm). Influence of rotational speed for smooth and baffled discs was studied. Results indicated that there was no considerable mass transfer limitation for new designs above approximately 150 rpm. For description of flow regime in the reactor residence time distribution (RTD) measurements was performed experimentally. According to RTD data, reactor was accurately modeled using tanks-in-series model. The estimated equivalent number of tanks-in-series in baffled discs were 8 and 10 compared to 4 for smooth disc. The Langmuir-Hinshelwood (L-H) kinetic model was combined with hydrodynamic model for prediction of degradation of phenol and rate coefficients. Predicted results were in agreement with experimental data.

Erosion Wear Investigation of HVOF Sprayed WC-10Co4Cr Coating on Slurry Pipeline Materials

In the present work, erosion wear due to slurry mixture flow has been investigated using a slurry erosion pot tester. Erosion tests are conducted on three different slurry pipe materials, namely, mild steel, SS202, and SS304, to establish the influence of rotational speed, concentration, and time period. In order to increase erosion wear resistance, a high-velocity oxy-fuel (HVOF) coating technique is used to deposit a WC-10Co4Cr coating on the surface of all piping materials. Experimental results show that rotational speed is a highly-influencing parameter for the erosion wear rate as compared to solid concentration, time duration, and weighted mean diameter. WC-10Co4Cr HVOF coating improved the erosion resistance of piping materials up to 3.5 times. From experimental data, the exponents of solid concentration, velocity, and the size of particles are calculated for the empirical erosion wear equation. A functional equation of the erosion wear rate is developed. The predicted erosion wear is in agreement with the experimental data and found to be within a deviation of ±12%.

Tribological analysis of WC–10Co–4Cr and Ni–20Cr2O3 coating on stainless steel 304

Centrifugal slurry pump is widely used for transportation of solids through pipeline in many chemical and mining industries. Erosion wear considered as one of the important parameter which plays significant role in slurry transportation system by affecting both initial cost and life of its components. In the present work, erosion wear due to solid–liquid mixture has been investigated using a slurry erosion pot tester. The erosion tests have been conducted on centrifugal slurry pump material stainless steel (SS304) to establish the influence of rotational speed, particle size, solid concentration and time duration. Sand and fly ash were taken as erodent materials with solid concentrations ranging from 30 to 60% (by weight). The experiments were performed at four different speeds namely 600, 900, 1200 and 1500rpm with time duration of 90, 120, 150 and 180minutes. WC–10Co–4Cr and Ni–20Cr2O3 coating powders were used to increase the erosion wear resistance. Coating powders are deposited on pumping material by supersonic flame of high velocity oxygen fuel (HVOF) coating. Experimental results indicate that erosion wear has high dependence on rotational speed, time duration and nature of erodent solid particles. Significant improvement in erosion wear resistance was also observed by using WC–10Co–4Cr coating over Ni-20Cr2O3.

Influence of Rotational Moulding Process Parameters on Accuracy of Polymer Casts

The present paper describes the experimental tests undertaken to examine the influence of rotational speeds of two axes of the mould on properties of casts produced in the rotational moulding process. The general principles of this polymer processing technology have been described. The main applications have been introduced, and leading advantages and typical disadvantages of rotational moulding process have been told over. Rotational mould's speed around axes was changed, and a thickness of cast walls has been measured also with average surface concentration of colorant in cast walls. Laboratory test stand, processing properties of polymer, also test program and experimental test methodology have been described.

Friction riveting (‘FricRiveting’) of 6056 T6 aluminium alloy and polyamide 6: influence of rotational speed on the formation of the anchoring zone and on mechanical performance

Metal-polymer hybrid structures can be used as an alternative solution for reducing weight and fuel consumption in the transport industry, which aims to minimise the emission of harmful gases that have a greenhouse effect. Friction riveting is a relatively new technique for joining metal-polymer hybrid structures. The process is based on the generation of frictional heat between the components, resulting in the plastic deformation of the end of the metal rivet, which is anchored inside the polymer component. This study assessed the technical feasibility of joining AA 6056 T6 and PA6, focusing on the influence of the rotational speed of the rivet on the mechanical performance of the joints. The maximum temperature reached during the process increased with the rotational speed, from 291 ± 6 °C with 10,000 rev/min to 375 ± 5 °C with 15,000 rev/min. The use of higher rotational speeds led to the tip of the rivet undergoing plastic deformation during the friction phase. This produced mechanically stronger joints, because the metal rivet was anchored more securely in the polymer block. The AA 6056 T6-PA6 joints perform well in terms of tensile strength, reaching 85% of the tensile strength of the metal rivet. We therefore confirmed that it is possible to join AA 6056 T6 and PA6 using the technique of friction riveting, and that rotational speed directly affects the tensile strength of the joints.

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

The wear and contact resistance of sliding contacts are typically researched with a pin-on-disk experiment that prevents dynamic excitation. However, in electrical machines, the brush clearance enables dynamic excitation, resulting in flexible body dynamics. To research the wear and contact resistance during dynamical excitation, an in-situ experimental approach is introduced here, with the influences of rotational speed, electrical current, and temperature being assessed. This research shows that a small wear rate and contact resistance are possible at 10,000 and 5000 RPM if the electrical current is higher than 3 A. It was also found that the contact resistance decreased with an increased ambient temperature, electrical current, and rotating speed, whereas the wear rate increased with the rotating speed at low current density and low ambient temperature.

Experimental study to the influences of rotational speed and blade shape on water vortex turbine performance

Water vortex turbine utilizes the natural behaviour of water to form free surface vortex for energy extraction. This allows simple construction and ease of management on the whole water vortex power plant system. To our findings, the literature study specifically on water vortex turbine is inadequate and low efficiency was reported. Influences of operating speed and blade shape on turbine performance are the two parameters investigated in this study. Euler Turbomachinery Equation and velocity triangle are used in the improvement analysis. Two turbines with flat blades and curved blades are tested and compared. Both turbines show similar rotational speed at no load condition. This suggested that the circulation force of the water vortex has more dominant effect on the turbine rotational speed, compared to the turbine’s geometry. Flat-blades turbine showed maximum efficiency of 21.63% at 3.27 rad/s whereas curved-blades turbine showed 22.24% at 3.56 rad/s. When operating load is applied, the backward-leaning curve helps the turbine blades to reduce the disturbance on the water vortex, and hence provide a better performance.

Critical rotational speed, critical velocity of fluid flow and free vibration analysis of a spinning SWCNT conveying viscous fluid

In this article, the influences of rotational speed and velocity of viscous fluid flow on free vibration behavior of spinning single-walled carbon nanotubes (SWCNTs) are investigated using the modified couple stress theory (MCST). Taking attention to the first-order shear deformation theory, the modeled rotating SWCNT and its equations of motion are derived using Hamilton’s principle. The formulations include Coriolis, centrifugal and initial hoop tension effects due to rotation of the SWCNT. This system is conveying viscous fluid, and the related force is calculated by modified Navier–Stokes relation considering slip boundary condition and Knudsen number. The accuracy of the presented model is validated with some cases in the literatures. Novelty of this study is considering the effects of spinning, conveying viscous flow and MCST in addition to considering the various boundary conditions of the SWCNT. Generalized differential quadrature method is used to approximately discretize the model and to approximate the equations of motion. Then, influence of material length scale parameter, velocity of viscous fluid flow, angular velocity, length, length-to-radius ratio, radius-to-thickness ratio and boundary conditions on critical speed, critical velocity and natural frequency of the rotating SWCNT conveying viscous fluid flow are investigated.

STUDY ON LOAD DISTRIBUTION OF PLANETARY ROLLER SCREW BASED ON THERMO-MECHANICAL COUPLING

In this paper, a thermo-mechanical coupling based load distribution model considering two installation modes is developed by using the finite element method. The model is verified by comparing with the theoretical model. The effects of installation modes, load conditions and working temperature on the load distribution are analyzed systematically. The numerical results show that the phenomenon of threads separated from meshing occurs with the increase of rotational speed of screw and loads. The influences of rotational speed of screw and loads on load distribution on screw side are larger than that of the nut side under two installation modes. Uneven distributions of loads increase with the increase of inside and outside temperatures, and the uneven rate of nut side is higher than that of screw side.

Friction Stir Welding of Dissimilar Al-Cu Lap Joints with Copper on Top

Friction stir welding (FSW) is a solid state welding process that has been studied for dissimilar welding applications, especially aluminum and copper. However, the quality of dissimilar Al/Cu FSW joints is often impaired due to the formation of intermetallic compounds (IMCs), which affect both mechanical and electrical properties. This paper investigates the feasibility of FSW in producing dissimilar Al/Cu lap joints were copper is positioned over aluminum. In order to access the influence of rotational speed over the resulting joint, four different rotational speeds were tested for the same welding speed. The produced joints were then evaluated in terms of weld appearance, defects and the electrical resistance of the welded joints. Visual and ultrasound inspection indicated no discontinuity in any of the produced samples. Electrical resistance results indicate no influence of rotational speed. Moreover, electrical resistance of the Al/Cu FSW lap joints were smaller than the average between the electrical resistances of single metal joints welded with the tested materials in similar conditions. The experiments indicate that is possible to produce sound Al/Cu lap welds for the parameter window used, including the positioning of copper over aluminum, that is discouraged by literature. The small values of electrical resistance indicate no deleterious effect of IMCs over this characteristic.

Influence of rotational speed on process characteristics in friction surfacing of Ti-6Al-4V

ABSTRACTFriction surfacing process is employed to deposit metallic coatings, whereby similar and dissimilar material combinations can be realized. The process can be applied as a local repair technology, or the coating material can locally modify the surfaces. One advantage of this process is that the coatings are deposited in solid state without reaching the melting range of materials, thereby avoiding dilution with the substrate. The involved severe plastic deformation under high temperatures alters the microstructure of the coating material, leaving it fully dynamically recrystallized. The current work focuses on deposition of Ti-6Al-4V coatings. For that material, the process parameter rotational speed plays a major role in the material’s response during processing. Two different regimes with a threshold at 2000 min−1 exist, upon which the flow behavior of Ti-6Al-4V significantly differs, affecting among others the coating dimensions. Microstructural analysis reveals that the material is deformed in a high temperature β phase, and the high cooling rates (46.4 Ks−1) lead to martensitic transformation. The β grain size differs in the low and high rotational speed regimes. This study shows that metallurgical processes play an important role in friction surfacing, since they influence all relevant process characteristics, including microstructure, material efficiency and process forces.

Simulation of temperature distribution in hot filament chemical vapor deposition diamond films growth on SiC seals

In this study, the temperature and gas velocity distributions in hot filament chemical vapor deposition (HFCVD) diamond film growth on the end surfaces of seals are simulated by the finite volume method. The influence of filament diameter, filament separation and rotational speed of the substrates is considered. Firstly, the simulation model is established by simplifying operating conditions to simulate the temperature and gas velocity distributions. Thereafter, the deposition parameters are optimized as 0.6mm filament diameter, 18mm filament separation and 5 r/min rotational speed to get the uniform temperature distribution. Under the influence of the rotational speed, the difference between temperature gradients along the directions perpendicular to the filament and parallel to the filament becomes narrow, it is consistent with the actual condition, and the maximum temperature difference on the substrates decreases to 7.4 ◦C. Furthermore, the effect of the rotational speed on the gas velocity distribution is studied. Finally, diamond films are deposited on the end surfaces of SiC seals with the optimized deposition parameters. The characterizations by scanning electron microscopy (SEM) and Raman spectroscopy exhibit a layer of homogeneous diamond films with fine-faceted crystals and uniform thickness. The results validate the simulation model.

Microstructure, texture and mechanical properties of friction stir welded butt joints of 2A97 Al[sbnd]Li alloy ultra-thin sheets

1.4 mm 2A97 AlLi alloy ultra-thin sheets were welded by friction stir butt-welding at different rotational speeds. The influences of rotational speeds on microstructure, texture and mechanical properties of joints were investigated in detail. Microstructure observation shows that the grains in the nugget zone and thermo-mechanical affected zone of joints have a significant refinement compared with the base metal. In addition, the grain size in the joints increased with increasing the rotational speed. Electron backscatter diffraction analysis reveals that the intensity of the original rolling texture including Brass, Copper and S components of the base metal was weaken after welding, and there were some newly generated recrystallization textures in the nugget zone and the thermo-mechanical affected zone of joints, such as Cube and Cube ND components. Moreover, the intensity of recrystallization texture of joints increased while that of rolling texture decreased with increasing the rotational speed. With the change of rotational speed, the proportion of LAGBs and recrystallized grains changed due to the differences of heat input. Tensile test results show that the mechanical properties of joints increased firstly to a maximum and then decreased with increasing the rotational speed from 600 rpm to 1200 rpm. The ductility of joints is also affected by the microstructure, grain boundaries and textures. The joints with the small-sized grains, large proportion of LAGBs and deformation textures possess the sound elongation. All joints failed in the weld center with the toughness or toughness-brittleness fracture modes.

Magnetic nanoparticles stimulation to enhance liquid-liquid two-phase mass transfer under static and rotating magnetic fields

Rotating magnetic field (RMF) was applied on a micromixer to break the laminar flow and induce chaotic flow to enhance mass transfer between two-immiscible organic and aqueous phases. The results of RMF were compared to those of static magnetic field (SMF). For this purpose, experiments were carried out in a T-micromixer at equal volumetric flow rates of organic and aqueous phases. Fe3O4 nanoparticles were synthesized by co-precipitation technique and they were dissolved in organic phase. Results obtained from RMF and SMF were compared in terms of overall volumetric mass transfer coefficient (KLa) and extraction efficiency (E) at various Reynolds numbers. Generally, RMF showed higher effect in mass transfer characteristics enhancement compared with SMF. The influence of rotational speeds of magnets (ω) in RMF was investigated, and measurable enhancements of KLa and E were observed. In RMF, the effect of magnetic field induction (B) was investigated. The results reveal that at constant concentration of nanoparticles, by increasing of B, mass transfer characteristics will be enhanced. The effect of various nanoparticles concentrations (ϕ) within 0.002–0.01(w/v) on KLa and E at maximum induction of RMF (B=76mT) was evaluated. Maximum values of KLa (2.1±0.001) and E (0.884±0.001) were achieved for the layout of RMF (B=76mT), ω=16rad/s and MNPs concentration of 0.008–0.01(w/v).

Numerical simulation of tip clearance impact on a pumpjet propulsor

Numerical simulation based on the Reynolds Averaged Navier–Stokes (RANS) Computational Fluid Dynamics (CFD) method had been carried out with the commercial code ANSYS CFX. The structured grid and SST k–ω turbulence model had been adopted. The impact of non-condensable gas (NCG) on cavitation performance had been introduced into the Schnerr and Sauer cavitation model. The numerical investigation of cavitating flow of marine propeller E779A was carried out with different advance ratios and cavitation numbers to verify the numerical simulation method. Tip clearance effects on the performance of pumpjet propulsor had been investigated. Results showed that the structure and characteristics of the tip leakage vortex and the efficiency of the propulsor dropped more sharply with the increase of the tip clearance size. Furthermore, the numerical simulation of tip clearance cavitation of pumpjet propulsor had been presented with different rotational speed and tip clearance size. The mechanism of tip clearance cavitation causing a further loss of the efficiency had been studied. The influence of rotational speed and tip clearance size on tip clearance cavitation had been investigated.

Microstructure evolution and mechanical properties of rotary friction welded TC4/SUS321 joints at various rotation speeds

The dissimilar joints between TC4 titanium alloy rod and SUS321 stainless steel rod were produced by rotary friction welding (RFW). The influence of rotation speed was investigated on the morphologic distribution of intermetallics (IMCs) formed at the interface and on the mechanical properties that were assessed by tensile test and microhardness. Results showed that the morphology of IMCs, mainly TiFe2 and TiFe formed on SUS321 side, transforms from dispersive pattern to laminar pattern as the rotation speed increases from 400 to 1800rpm with a transition point around 600rpm. The joint strength increases and then decreases after reaching a maximum value with increasing rotation speed. The highest tensile strength of 468MPa, corresponding to the joint efficiency of 90%, was achieved at 600rpm, where the valley value of equilibrium interfacial temperature was obtained. All of the dissimilar RFWed joints failed completely in cleavage fracture mode along the boundary between IMCs layers and TC4 matrix.

Characterization of granular mixing in a helical ribbon blade blender

Experiments of bulk solid mixing in a twin ribbon blade blender have been performed in this work in order to characterize mixing behavior in such a mixer for binary mixtures with different cohesionless materials. The effects of fill height and blade rotation speed on mixing homogeneity have been studied. Mixing homogeneity was determined by sampling. It has been observed that mixing is relatively fast towards a final mixing state within approximately 100 blade rotations for different combinations of material, fill height and blade rotational speed. Moreover, these final mixing states seemed stable within a range of fluctuations, which may prove useful in determining an optimal mixing time for binary, cohesionless particle mixtures and potentially lead to a reduction in the required number of blade rotations in mixers of this type in industry. Mixing homogeneity results indicated an increased final mixing homogeneity for increasing fill height, most clearly in the range of 30–70vol.% in the studied twin ribbon blade mixer. The torque on one of the shafts was determined. The latter results showed that no significant influence of rotational speed on the required torque for the tested mixtures at rotational velocities in the range of Fr 0.17–1.1 could be determined for most combinations of the tested materials and fill heights in this work. The quantitative characterization of mixing behavior with the two key parameters mixing homogeneity and torque on the shaft may be used for mixer validation of DEM simulations.

The Study of Synchronous Belt Transmission Stability with the Influence of Rotation Speed and Tension

The vibration of belt affects the transmission stability, products noise and the life of automotive synchronous belt. The mathematical model of longitudinal vibration was established through analyzing the longitudinal vibration of automotive synchronous belt. The vibration dynamic measurement device was developed based on the laser displacement triangulation measurement principle, aiming at RU style arc teethed synchronous belt transmission process, measured the variety of amplitude over time at the middle of the belt span when rotation speed was 600r/min, 1200r/min, 1800r/min and tensile force was 320N, 480N, 640N, obtained the rules of amplitude and frequency change along with the variation of rotation speed and tensile force. It has significance on improving the transmission stability of arc teeth synchronous belt, reducing the transmission noise and prolonging the service life of belt.