Rotation Of Cylinder Research Articles

On Spiral Turbulent Flow in an Annular Concentric Channel

The paper presents the results of Newtonian-fluid spiral flow simulation in an annular channel. The simulation parameters were dimeters ratio of 0.5; Re = 100 ÷ 10,000 and dimensionless inner cylinder rotation rate χ = 0.2 ÷ 5. The turbulent flow regimes were simulated using URANS, a non-stationary statistical turbulence model. While simulation, the following flow regimes were detected: homogeneous flow without pronounced structures (Re = 100, χ⩽3 and Re=300, χ⩽0.5); flow with Görtler-type continuous spiral vortices near inner cylinder (Re = 300, χ=1 and Re = 1000 ÷ 10000, χ = 0.5); flow with Taylor-type vortices (Re = 100, χ⩾3 and Re = 300, χ⩾3); flow with small-scale Görtler-type vortices near both channel walls (Re ⩾ 1000 and χ⩾1). The spiral spin of Görtler-type vortices near the outer cylinder was co-directed with the rotation of the inner cylinder, while the vortices near the inner cylinder spin against the rotation. Formation of large Taylor-type vortex structures led to a decrease in the channel skin friction coefficient faRe. Görtler-type vortices interaction near the channel walls triggered the formation of small-scale structures increasing in the channel resistance as the Reynolds number and rotation speed grew.

Selection of the circumferential speed of the spiked cylinders of cotton cleaners - raw from small trash

This article presents the materials of the theoretical analysis of the working bodies of the machine for cleaning cotton raw materials from small trash. And also the influence of the speed of rotation of the peel cylinder of the cleaner on the separation of small trash from raw cotton was studied. It has been proven that a differential increase in the speed of the spiked will lead to an increase in the cleaning efficiency of the machines. It is recommended that the speed of the first cylinder be 10 m / s, the speed of the second cylinder 11 m / s, the speed of the third cylinder 12 m / s, etc.

Rotational Particle Separation in Solutions: Micropolar Fluid Theory Approach.

We develop a new mathematical model for rotational sedimentation of particles for steady flows of a viscoplastic granular fluid in a concentric-cylinder Couette geometry when rotation of the Couette cell inner cylinder is prescribed. We treat the suspension as a micro-polar fluid. The model is validated by comparison with known data of measurement. Within the proposed theory, we prove that sedimentation occurs due to particles’ rotation and rotational diffusion.

Numerical simulations of the polydisperse droplet size distribution of disperse blends in complex flow

The blend morphology model developed by Wong et al. (Rheologica Acta, 2019), based on Peters et al. (J Rheol 45(3):659–689, 2001), is used to investigate the development of the polydispersity of the disperse polymer blend morphology in complex flow. First, the model is extended with additional morphological states. The extended model is tested for simple shear flow, where it is found that the droplet size distribution does not simply scale with the shear rate, because this scaling does not hold for coalescing droplets. Subsequently, the model is applied to Poiseuille flow, showing formation of distinct layers, which occurs in realistic pressure-driven flows. Finally, the model is applied on an eccentric cylinder flow, where histograms are made of the average droplet size throughout the domain. It is observed that outer cylinder rotation results in narrow distributions where the small droplets are relatively large, whereas inner cylinder rotation results in broad distributions where the small droplets are significantly smaller than in the case of outer cylinder rotation. Eccentricity seems to only have a minor effect if the maximum shear rate is held constant. The flow profile and history in combination with the maximum shear rate strongly determine how the polydisperse droplet size distribution develops.

Performance Test of Various Teeth Diameter of Cylinder Type Sago Rasping Machine

Traditional method of sago starch extraction was a time and labor intensive process. The most laborious stage is pith disintegration which is done by using hammer-like tools called pounder. However, the use of rasping machine to disintegrate the pith is saving time and energy significantly. The objective of this study was to investigate the effect of teeth diameter and cylinder rotation speed on performance of cylinder type sago rasping machine. In the experiment, four variations of teeth diameter i.e. 3mm, 4 mm, 5 mm and 6 mm, and three levels of cylinder rotation speed i.e. 1500 rpm, 2000 rpm and 2500 rpm were examined. Results showed that both teeth diameter and cylinder rotation speed significantly affect the rasping capacity. Likewise teeth diameter also significantly affect on starch percentage and starch losses in waste. Meanwhile, cylinder rotation speed and the interaction of the two factors have no significant effect on the starch percentage and starch loss in waste. The highest performance was obtained at the condition of teeth diameter 3 mm with cylinder rotation speed of 2500 rpm. The performance of the machine at the condition were (a) rasping capacity 2282 kg h-1, (b) starch percentage 33.02 %, (wb), (c) starch loss in waste 8.77 %.

Study of the Shape of a Microwave Chamber for Heating a Dielectric Object

Currently, microwave energy is actively used in various industrial spheres for heating dielectric materials. In order to ensure uniform heating, it is necessary to obtain a uniform distribution of absorbed power in the volume of a dielectric. In this paper, we consider two models of a microwave chamber for heating a dielectric object – a rectangular chamber and a cylindrical chamber. Computer simulation was performed in the FEKO software for several cases: using two and four radiation sources and using two different dielectrics, with parameters corresponding to water and wheat. The results show that a cylindrical chamber provides a more uniform distribution of absorbed power in the inner volume, and therefore, allows to obtain a more uniform heating of the dielectric object inside it, than a rectangular chamber. One possible variant of implementation of a chamber for microwave heating of a dielectric object may be a rotating cylindrical chamber. Its application will allow obtaining uniform heating with a smaller number of emitters due to the choice of the optimal cylinder rotation speed.

Thermal behaviour of heated stationary inner cylinder of a concentric vertical annulus formed with rotating outer cylinder

Experimental studies have been conducted to investigate the convective heat transfer from the inner stationary heated cylinder of a vertical concentric annulus with outer cylinder rotating, corresponding to rotation speeds from 500rpm to 1000rpm. The centrifugal force arising due to the outer cylinder rotation and the buoyant force developed due to the heat generated from the stationary inner cylinder has been characterized by using a non-dimensional number denoted as Rotation parameter (ζ = Reω 2/Gr). The influence of Rotation parameter on the convective thermal behaviour of the heated stationary inner cylinder has been explained.

Experimental study to observe the change of flow characteristics on a stationary cylinder and a rotary cylinder with two different rotational speeds

Property of flow field over a dynamic body has extensively been considered as a topic of interest in recent past as an aerodynamic and futuristic solution. However, a stiff object of common shape is fixed inside a wind tunnel. The drag force asserted on it by the wind is ascertained by a new method based on plain fundamental Physics ideas, provided one has a solver, any solver, for the resembling dynamic Navier-Stokes equation which determines the wind velocity field around the object. The method is completely usual, but here we apply it to the conventional problem of a long cylinder vertical to the wind. For different Reynolds number the comparative analysis between the flow characteristics of non-rotating and rotating cylinder has been done here. And for the rotating cylinder two rotational speeds have been provided to analyze and compare the effects. Main focus of this study is to determine the characteristics of flow field created over a rotating cylinder and non-rotating cylinder and also find out the variation of this effect over different flow velocities and rotational speeds. This study differentiates among the performances and sets up characteristics graphs which helps to find out more scopes about flow field. The main inspiration behind this study is to find out the Magnus effect asserted on an object in motion. The slightest variation of flow field leads to a certain amount of impact which can be a futuristic solution for energy problems. So, an attempt has been made to find out this variation using closed loop wind tunnel and a bluff body, in this case a cylinder. Flow over the cylinder when it has a certain rpm significantly changes than that of when it is not rotating and for different rotational speeds change is even more noticeable. It is suggested to use a subtle Pitot-Static Tube for measuring the velocity.

Radiative swirl motion of hydromagnetic Casson nanofluid flow over rotary cylinder using Joule dissipation impact

In this article, the heat transfer is examined in spinning flow of the Casson nanofluid. The spinning motion is produced with the help of stretching and rotating cylinder. In current work two cases, both for constant and variant axial temperature over the exterior of the spinning cylinder are studied. For controlling the rate of heat transfer, some heat effects such as heat generation/absorption, Joule heating and thermal radiations have been considered for flow system. For investigation the influence of thermophoretic force and Brownian motion exerted by Casson nanofluid, the famous Buongiorno model has been employed. The modeled equations have converted to dimensionless form using a set of similar variables. To improve the solution convergence of flow equations a compressed variable is also employed. As the main outcome of this work, it has observed that, with growing values of Reynolds number and magnetic parameter the flow characteristics reduce in all directions. A growth in temperature profile is also observed for constant wall temperature (CWT), while a reduction is noticed in temperature profile for prescribed surface temperature (PST). Moreover, the concentration of fluid reduces with growing values of Prandtl and Lewis numbers.

Controlling the flow and heat transfer characteristics of power-law fluids in T-junctions using a rotating cylinder

In this work, the combined influence of the power-law rheology and isothermal rotating cylinder has been investigated numerically on the flow and heat transfer characteristics in a T-channel. The cylinder placed at the T-junction imitates the functioning of a rotating valve which controls the flow rate and the enthalpy distribution of the exiting streams in two branches. The range of parameters considered in this work is as: Reynolds number, 1 < Re ≤ 50, power-law index, 0.2 ≤ n ≤ 1, Prandtl number, 10 ≤ Pr ≤ 100 and non-dimensional circumferential velocity of the cylinder, −5 ≤ α ≤ 5. Results suggest that the rotating cylinder can be used as a technique to create and/or reduce the formation of momentum and thermal boundary layers in the flow domain. The rotational velocity (α) and power-law flow index (n) are seen to have a strong effect on the critical Reynolds number for both the main and side branches. The hydrodynamic forces acting over the cylinder surface exerted by the fluid in the flow and perpendicular to the flow direction show a strong relationship with the cylinder rotation. For a particular combination of the studied parameters, these forces are also seen to be negative. Further, it is interesting to note that as the power-law index increases, the flow split ratio decreases while it shows an opposite trend with the Reynolds number. It can also be varied by switching the rotation direction. The dimensionless exiting temperature and enthalpy distribution are seen to have a strong relationship with the direction of rotation, fluid power-law index, Reynolds and Prandtl numbers. The mean values of the Nusselt number are seen to increase and/or decrease with the rotational velocity. For the anticlockwise rotation, the maximum suppression in the heat transfer is seen to be 79% while 62% for the clockwise rotation for the Newtonian fluid behaviour at low Prandtl number and high Reynolds numbers.

A Visualization Framework for Multi-scale Coherent Structures in Taylor-Couette Turbulence.

Taylor-Couette flow (TCF) is the turbulent fluid motion created between two concentric and independently rotating cylinders. It has been heavily researched in fluid mechanics thanks to the various nonlinear dynamical phenomena that are exhibited in the flow. As many dense coherent structures overlap each other in TCF, it is challenging to isolate and visualize them, especially when the cylinder rotation ratio is changing. Previous approaches rely on 2D cross sections to study TCF due to its simplicity, which cannot provide the complete information of TCF. In the meantime, standard visualization techniques, such as volume rendering / iso-surfacing of certain attributes and the placement of integral curves/surfaces, usually produce cluttered visualization. To address this challenge and to support domain experts in the analysis of TCF, we developed a visualization framework to separate large-scale structures from the dense, small-scale structures and provide an effective visual representation of these structures. Instead of using a single physical attribute as the standard approach which cannot efficiently separate structures in different scales for TCF, we adapt the feature level-set method to combine multiple attributes and use them as a filter to separate large- and small-scale structures. To visualize these structures, we apply the iso-surface extraction on the kernel density estimate of the distance field generated from the feature level-set. The proposed methods successfully reveal 3D large-scale coherent structures of TCF with different control parameter settings, which are difficult to achieve with the conventional methods.

Radial vibrations on an elastic medium subjected to rotation and magnetic field

Based on the one-dimensional elastic theory, the radial vibrations of cylindrical isotropic embedded in an elastic medium are studied in the paper. The effect of the magnetic field of the radial vibrations of an elastic hollow cylinder with rotation is researched as well. The one-dimensional equation of elastodynamic is solved in terms of radial displacement. The frequency equation is obtained when the boundaries are free and fixed; the mixed boundary condition is numerically examined. The determination is concerned with the eigenvalues of the natural frequency of the radial vibrations in the case of harmonic vibrations. The effect of the magnetic field and rotation on the natural frequencies were explored. It was shown that the dispersion curves of guided waves were significantly influenced by the magnetic field and rotation of the elastic cylinder. Numerical results are given and graphically illustrated in each considered case. The natural frequencies and mode shapes are calculated numerically, and the effects of rotating, magnetic field, and variable thickness are discussed. It is observed that an increase of the magnetic parameter, as well as the rotation parameters, brings results closer to the classical cylinder theory results. Furthermore, the current study can be applied to the design of microplates and nanoplates and their optimal usage. The results indicate that the effects of the magnetic field and rotation are very pronounced.

Effect of bio-based flow improver on the microscopic and low-temperature flow properties of waxy crude oil

Wax formation creates flow assurance problems in the production and transportation of waxy crude oil. Flow improvers are added to waxy crude in order to reduce handling cost. Bio-based flow improvers derived from cheap renewable resources are attractive as cost-effective, eco-friendly alternatives to the conventional additives. Natural cashew nut shell liquid extracted from waste biomass (Anacardium occidentale shells) was derivatized and applied as flow improver for waxy crude oil. Effect of the additive on wax formation in crude oil was studied by cross-polarized microscopy, while the change in oil flow properties was evaluated using a rotational coaxial cylinder viscometer. Micrographs of the waxy crude were processed and analyzed with image J software. The microscopic properties of the wax crystals were characterized using Feret diameter, crystal area, aspect ratio, circularity, solidity and boundary fractal dimension. The pour point of doped crude oil was depressed by − 18 °C and the wax area fraction reduced by 40% due to wax inhibitive effect of the additive. The presence of the additive resulted in evolution of smaller, rounder and more regular wax crystals with smoother and more even surfaces indicated by reduction in the Feret diameter, aspect ratio and boundary fractal dimension of wax crystals in doped oil, and an increase in crystal circularity and solidity. The shear stress and viscosity of doped oil were reduced by 86.8% and 85.0%, respectively. The flow improvement effect of the CNSL derivative is linked to its effect on morphology and microstructure of wax crystals in the crude oil.

АЭРОДИНАМИКА ТУРБУЛЕНТНОГО ПОТОКА ВО ВРАЩАЮЩЕМСЯ ПОЛУЗАМКНУТОМ ЦИЛИНДРЕ

The mathematical model and results of a numerical study of swirling turbulent air flow characteristics in a semi-closed cylinder rotating around a symmetry axis are presented. A physical and mathematical model is used to describe aerodynamics of the stationary isothermal axisymmetric swirling flow, which includes the Navier-Stokes equations in cylindrical coordinates. The study of turbulence characteristics is carried out using the composite model Menter SST (Shear Stress Transport). The numerical solution is obtained using a chess grid. Nodes for axial and radial velocity components are located in the middle of the control volume faces for scalar quantities. Calculations are performed on a grid with 2000 and 1700 nodes in the axial and radial directions, respectively. The grid refinement is performed near the walls and in the areas with large velocity gradients. The calculated results show that the main grid refinement by 2 times in the axial and radial coordinates leads to a change in the values of the main variables by less than 1%. It is shown that the flow structure is determined by the rotational speed and cylinder height. Analyzing the calculated results, the ratio of the cylinder height to the angular velocity of the cylinder rotation is obtained, which ensures the formation of a quasi-solid rotation zone in the near-edge region.

Synthesis and Electrochemical Performance Analysis of LiNiO2 Cathode Material Using Taylor-Couette Flow-Type Co-Precipitation Method

A LiNiO2 cathode material with a layered structure and a high capacity was synthesized by co-precipitation with Taylor−Couette flow. Taylor−Couette flow is caused by the rotation of an inner cylinder in a device consisting of two concentric shaft cylinders. A regular donut-shaped vortex is developed above a certain rotational speed of the inner cylinder. Ni(OH)2 precursors synthesized by co-precipitation with the Taylor–Couette flow were sintered at 600 °C, 650 °C, 700 °C, and 750 °C. The LiNiO2 cathode material synthesized at 700 °C exhibited the highest discharge capacity of 233 mAh g−1. It was confirmed that the cyclability and rate performance of the LiNiO2 cathode material improved at other sintering temperatures.

Rotating cylinder and magnetic field on solid particles diffusion inside a porous cavity filled with a nanofluid

This study deals with the roles of a magnetic field and circular rotation of a circular cylinder on the dissemination of solid phase within a nanofluid-filled square cavity. Two wavy layers of the non-Darcy porous media are situated on the vertical sides of a cavity. An incompressible smoothed particle hydrodynamics (ISPH) method was endorsed to carry out the blending process concerning solid phase into nanofluid and porous media layers. Initially, the solid phase is stationed in a circular cylinder containing two open gates. Implications of a buoyancy ratio ( N = −2: 2), Hartmann number ( Ha = 0: 100), rotational frequency [Formula: see text], Darcy parameter [Formula: see text], Rayleigh number [Formula: see text], nanoparticles parameter [Formula: see text], and amplitude of wavy porous layers [Formula: see text] on the lineaments of heat/mass transport have been carried out. The results revealed that the diffusion of the solid phase is permanently moving toward upward except at opposing flow mode [Formula: see text] toward downward. The lower Rayleigh number reduces the solid-phase diffusions. A reduction in a Darcy parameter lessens the nanofluid speed and solid-phase diffusions in the porous layers. A reduction in [Formula: see text] from [Formula: see text] to [Formula: see text] diminishes the maximum of streamlines [Formula: see text] by 13.19% at [Formula: see text], by 46.75% at [Formula: see text], and by 74.75% at [Formula: see text].

AXIAL FLUX PROFILE IN THE ADVANCED TEST REACTOR

This work demonstrates an approach to determine probability of perturbation of the axial profile of the thermal neutron flux in the Advanced Test Reactor. The axial flux profile is expected to follow a theoretical cosine shape, due to the minimal use of vertically-withdrawn shims. Reactivity is normally controlled by rotation of Outer Shim Control Cylinders, uniformly affecting neutron flux at all axial locations. The Advanced Test Reactor routinely accepts for irradiation experiments of a variety of designs. Among the analyses required by the safety basis approved by the United States Department of Energy is the characterization of a new experiment’s potential for perturbing the axial flux, which could exacerbate power peaking in the driver fuel. However, this perturbation can be more or less severe in different locations within the fuel. Therefore, the best characterization of axial flux perturbation requires knowledge of baseline axial flux. Such information is obtained by measuring decay in activated uranium flux wires irradiated at known positions in cooling channels in plate-type fuel elements. Due to variability in measured axial flux, it is not usually clear whether a given anomalous measurement is caused by an actual perturbation. Assuming normality in random measurement errors, the probability of an actual perturbation is quantified.

Magnetohydrodynamic (MHD) Flow in a Channel Including a Rotating Cylinder

Heat transfer analysis in channels and enclosures has significant attention nowadays. In the present work, fluid flow and heat transfer of a vertical channel consisting of a rotating cylinder utilizing nanofluid have been studied, numerically. Uniform magnetic field has been applied to the fluid field. Different cylinder rotation directions, Hartmann number and rotational velocity of cylinder configurations have been considered. The results indicate that by increasing the Hartmann number, for low values of non-dimensional angular velocity the average Nusselt number increases. In addition, in higher Hartmann numbers, the average Nusselt number does not change remarkably with non-dimensional angular velocity. Furthermore, studying lift and drag coefficients demonstrate that in a constant Hartmann number, the highest drag coefficient takes place in maximum cylinder angular velocity. Additionally, almost uniform distribution of drag coefficient can be seen in higher Hartmann numbers. The numerical results have been compared with the previously reported results. This comparison illustrates excellent agreement between them.

Impact Estimation of a Transient Temperature Field on the Service Life of the High Pressure Rotor of K-1000-60/3000 Turbine

The one of purposes of this paper is to estimation some impact on the service life of the high-pressure cylinder rotor of a typical high-speed turbine K-1000-60/3000. The residual life assessment of power equipment would require determining viability and damage of its base metal. Typical degradation mechanisms of steam turbine equipment include long-term strength reduction and low cycle fatigue accumulation. Intensity of their impact is determined by a numerical examination of equipment thermal (TS) and stress strain states (SSS) for standard operation modes. To perform a numerical examination of the stress strain state would require solving a thermal conductivity boundary problem in quasi-stationary (for nomal operation modes) and nonstationary models (for transients). It is convenient to solve such problems of mathematical physics through discretization of the calculation object using the finite element method (Chernousenko et al. 2018). The service life of steam turbine is determined as an individual one and is assigned based on the results of individual an inspection of a separate element or the largest group of single-type equipment elements of the considered plant. The fleet service life being reached is followed by diagnostics of specific units of power installations and analysis of their operation, measurement of actual dimensions of components, examination of structure, properties and damage accumulation in the metal, non-destructive testing and estimate of stress strain state and residual service life of the component. The results of performed studies are used to determine an individual service life of each element of energy equipment (Nikulenkov et al. 2018).

Mixed convection flow of hybrid nanofluid through a vented enclosure with an inner rotating cylinder

A numerical solution for the influence of an inner adiabatic rotating cylinder inside a vented cavity on mixed convection of hybrid nanofluid is presented in this study. The governing equations of mixed convection flow for an incompressible Newtonian hybrid nanofluid are assumed to be two-dimensional, steady, and laminar. These equations are solved numerically by using the finite volume technique. In this work, (Al2O3 –Cu/ water) is introduced as a hybrid nanofluid. The influences of relevant parameters including nanoparticle concentrations (0 ≤ φ1 ≤ 0.02 and 0 ≤ φ2 ≤ 0.02), cylinder radiuses (0.1 ≤ R ≤ 0.3), cylinder locations (0.25 ≤ δ ≤ 0.75), angular rotational speeds (−5 ≤ Ω ≤ 5), Grashof numbers (103 ≤ Gr ≤ 105) and Reynolds numbers (50 ≤ Re ≤ 500) are examined. The obtained data are exhibited by means of different qualitative and quantitative figures. The results show that the energy transport of hybrid nanofluid enhances with an increase in solid particle concentration, but it is associated with an increased pressure drop. With respect to the stationary cylinder, it is reported that the counter-clockwise cylinder rotation increases convective heat transfer whereas the clockwise direction has a reverse effect. In addition, for the counter-clockwise rotation of the cylinder, the heat transfer enhances when the position of the cylinder approaches the hot wall. The maximum heat transfer enhancement over the stationary cylinder with 21% occurs in case of R = 0.3 and δ = 0.5 under Gr = 104, φ1 = φ2 = 0.02, Re = 100 and Ω =5. The current study can provide useful guidelines to the designers of rotary heat exchangers.