Influence Of Centrifugal Force Research Articles

Investigation of a shift of whispering-gallery modes caused by deformations and tensions

The influence of centrifugal forces on angular velocity sensors that measure a spectral shift of whispering-gallery modes (WGMs) is investigated. Spherical WGM resonators of different materials are considered the sensing elements. The study is based on the results of the simulation in OOFELIE::Multiphysics software.

Enrichment and migration regularity of fine coal particles in enhanced gravity concentrator

Enrichment and migration regularity of coal particles in compound force field provided by Falcon concentrator were studied. Influence of centrifugal force and fluidization water pressure on the distribution rates and ash contents of materials that enriched in overflow, top separation area and bottom separation area were tested respectively. Radial velocity of fluidization water, having an important influence on the sedimentation of particles, was calculated and results show that radial velocity of fluidization water in top groove is greater than that in bottom groove, which contributed to the selectivity and recovery of combustible. Besides, density composition of products in different enrichment areas was studied. Results show that in the upward migration process, particles with high density are gradually captured. Therefore, the material density is gradually reduced from bottom to top separation area. Meanwhile, mismatch phenomena occurred as the existence of heavy particles in overflow, and light particles in the grooves. Based on the morphology analysis, it is can be deduced that particles mismatch is the results of the increase of drag coefficient since the irregular shape.

Particle Migration Regularity in Compound Force Field of Enhanced Gravity Concentrator

ABSTRACTStudies were performed on the particle migration in a compound gravity force field. Significant separation performance differences of narrow size fraction were observed by the distribution rates and ash content difference, response rule of the particle size, and density to the separation environment were analyzed. High weight distribution and high ash content of ultrafine particles in overflow were the main cause of the low selectivity of ultrafine particles, which lead to the contamination of products. Influence of centrifugal force and fluidization water pressure on the sorting process was studied. The essence of the separation was to find the equilibrium point that could achieve the best combination separation behavior of different grain size samples. It was necessary to remove fine particles before separation to improve the overall quality of fine coal separation. The sorting process can be expressed by a simple matrix equation. Thus, the separation performance difference of coal samples can be expressed by sorting function. Influence of centrifugal force, fluidization water pressure, and particle size on distribution rate was analyzed by mathematical model fitting.

Study of the Effect of Centrifugal Force on Rotor Blade Icing Process

In view of the rotor icing problems, the influence of centrifugal force on rotor blade icing is investigated. A numerical simulation method of three-dimensional rotor blade icing is presented. Body-fitted grids around the rotor blade are generated using overlapping grid technology and rotor flow field characteristics are obtained by solving N-S equations. According to Eulerian two-phase flow, the droplet trajectories are calculated and droplet impingement characteristics are obtained. The mass and energy conservation equations of ice accretion model are established and a new calculation method of runback water mass based on shear stress and centrifugal force is proposed to simulate water flow and ice shape. The calculation results are compared with available experimental results in order to verify the correctness of the numerical simulation method. The influence of centrifugal force on rotor icing is calculated. The results show that the flow direction and distribution of liquid water on rotor surfaces change under the action of centrifugal force, which lead to the increasing of icing at the stagnation point and the decreasing of icing on both frozen limitations.

Flow regime identification for upward two-phase flow in helically coiled tubes

Abstract Helically coiled tubes have excellent compactness, heat transfer efficiency, thermal stress adaptability and two-phase flow stability. The increasing application of two-phase flow in helically coiled tube devices necessitates a deep knowledge of phase distribution features for different flow regimes as well as flow regime transitions characteristics. This paper identified the flow regimes of air–water adiabatic two-phase flow in three helically coiled tubes using a double-sensor conductivity probe and high speed camera. Similar to the inclined straight tube, a total of six flow regimes were found in the helically coiled tubes. The influence of centrifugal force on the phase distribution was analyzed for each regime. A set of straight-forward flow regime transition criteria were proposed and then validated by benchmark experiments conducted in an inclined straight tube. These criteria were then used to generate flow regime maps based on the experiments with liquid superficial velocities ranging from 0.03 to 4.12 m/s and gas superficial velocities ranging from 0.03 to 16 m/s. Compared to the horizontal and inclined straight tubes, the helically coiled tube experienced shrinkage in the bubbly flow region; also, wavy and annular flows appeared at slower gas superficial velocities.

Contact stiffness determination of high-speed double- locking toolholder-spindle joint based on a macro- micro scale hybrid method

The stiffness of toolholder-spindle joint at high speeds plays an important role in the cutting efficiency and the machining accuracy. A double-locking toolholder (BTF type) is designed to improve the stiffness of joint. This paper presents a macro-micro scale hybrid method to determine the stiffness of double-locking toolholder-spindle joint at high speeds. In this method the finite element method and the three-dimensional fractal method are combined. It is assumed flat in macro-scale for the contact surfaces of joint. The finite element method is introduced to obtain the pressure distribution with the influence of centrifugal force at high speeds. In micro-scale, the contact surfaces are fractal featured and the three-dimensional fractal method is used to compute the stiffness based on the pressure. Experiments with BTF40-type toolholder are conducted to verify the efficiency of the proposed model in zero-speed case. The relationship between the stiffness and the technological parameters of the system can be derived based on the presented model. The upper limit of speed, the optimized range of each technological parameter are determined for obtaining the higher stiffness of joint. The results can provide theoretical basis for improving the cutting efficiency and the machining accuracy of high-speed machine tool.

Combustion of layers inorganic systems under rotation to produce composite and gradient materials

The new way of production of gradient materials is presented. Course of self-propagating high-temperature synthesis reactions in layered systems under the influence of centrifugal force and some methods of analysis of the process and products of reaction is described.

English

English

Latest Proofs of Validity of the Phenomenon of Phase Formation through a Stage of Liquid State in Metals Being Electrodeposited

The aim of the work was the experimental verification of the validity of the discovered phenomenon of phase formation through a stage of liquid state in metals being electrodeposited [1-3]. For that the features of formation of crystallographic texture in metals being electrodeposited under the influence of external (centrifugal) force in the directions opposite and along the texture axis were investigated. General idea for the fulfillment of new experiments was based on the fact that the degree of perfection of crystallographic texture appearing in metals being solidified from liquid state at the action of the external force significantly depends on the direction of the force action. A change of the degree of perfection of texture in metals being electrodeposited with the change of the direction of minor force action (in comparison with the value of plastic deformation creating texture in solids) will be a proof of the validity of the discussed phenomenon. Idea One and Its Realization. It is known that texture formation of metal during its solidification occurs by oriented crystallization in the direction perpendicular to the crystallization front. On the other hand, it is known that crystallographic texture of electrodeposited metal is the axial texture of growth with the axis perpendicular to the surface of a deposit. Assuming that crystallographic texture of metal being electrodeposited is formed as a result of oriented crystallization of continuously renewed metallic liquid, the action of centrifugal force directed perpendicular to the crystallization front and opposite to the texture axis will obstruct the formation of texture. The investigations of features of oriented structure formation in metals being electrodeposited in the field of centrifugal force were performed on copper and nickel samples. As a result the effect of suppression of the process of texture formation in metals being electrodeposited up to the complete disordering of crystal lattices of grains under the influence of external force in the direction opposite to the texture axis was discovered. Idea Two and Its Realization. It is known that texture formation during crystallization of metal occurs in the direction of the external force influencing the metal. At that the degree of perfection of texture of metal being solidified increases with the growth of values of the external force. Therefore, if metal being electrodeposited really passes through a stage of liquid state, then at the influence of centrifugal force on metallic liquid being solidified perpendicular to the crystallization front and along the texture axis the processes of formation and development of texture will intensify. Features of texture formation in metals being electrodeposited in the field of centrifugal force acting along the texture axis were investigated on copper and nickel samples. The effect of intensification of the texture formation process in metals being electrodeposited at the influence of external force directed along the texture axis was found. The comparative analysis of the degree of texture perfection of electrodeposited metals obtained at different directions of the force action during their phase formation was performed. It was found that regardless of the direction of the force influence the most significant change of the degree of texture perfection in metals being electrodeposited occurs at relatively low overloads. It was discovered that the action of external force in the direction opposite to the texture axis results in the more significant influence on the texture formation process in metals being electrodeposited in comparison with the force action along the texture axis. The obtained results prove the validity of the phenomenon of phase formation through a stage of liquid state in metals being electrodeposited.

Naturally Twisted Layered Anisotropic Rod Made of Reinforced Materials Research

In this paper, we consider the deformation of multilayer bars in torsion and tension. Thus, in the analyzed strength calculations rod having a rectangular cross section of the composite material. Namely, the choice of the structure of the material, satisfy the specifications of the rod in terms of stress-strain state in a torsion-bending coherence taking into account features of the composite materials. On the example with a layered core, being under the influence of centrifugal forces shows the effect of shifts between the layers on the redistribution of normal and shear stresses in layers. Depending on the magnitude of the anisotropy coefficient of the material used, normal and shear stresses in the outer layers is increased by 2-5 times. Comparison of these values ​​with limit stress for these layers allows you to select how the reinforcement of these layers. Collection of data about the influence of the stiffness of the individual layers by an angle promotion rod and durability allow the optimal folding of the reinforcing layers and the type of reinforcement and matrix.

The Study on Contact Angle of High-Speed Ball Screw

This paper aims to develop a new systematic analysis model to predict the contact angle of ball screw in high-speed condition. In order to investigate the contact angle between the ball and raceway, a proper mechanics model of ball screw should be established. Then, considering the influence of centrifugal force at high speed, the change of contact angle will be analyzed and solved. Finally, the different factors on the influence of contact angle in different locations are analyzed. This study provides the theory basis of studying kinematics of ball screw in high speed.

Numerical Simulation of Cold Swirl Field for Solid Fuel Ramjet with NACA Airfoil

In order to study the swirl flow characteristics in the solid fuel ramjet chamber, a new type of annular vane swirler with NACA airfoil is designed. The cold swirl flow field in the chamber is numerically simulated with different camber and t attack angle, while the swirl number , swirl flow field structure, total pressure recovery coefficient were studied. According to numerical simulation result, the main factors in swirl number are camber and angle of attack, the greater angle of attack, the greater the camber ,the stronger swirl will be. Results show that the total pressure loss is mainly concentrated in the inlet section, the total pressure loss cause by vane swirler is small. Radial velocity gradient exists in swirling flow, and increases with the swirl number. With the influence of centrifugal force and combustion chamber structure, the radial velocity gradient increases.

Bifurcation analysis of an electro-statically actuated micro-beam in the presence of centrifugal forces

In this paper, the influence of centrifugal forces on the stability of an electro-statically actuated clamped–clamped micro-beam has been investigated. The non-dimensional governing static and dynamic equations have been linearized using the step by step linearization method (SSLM), then, a Galerkin-based reduced order model has been used to solve the linearized equations. For constant value of a bias DC voltage and different values of angular velocity the equilibrium points of the corresponding autonomous system including stable center points, unstable saddle points and singular points have been obtained using the equivalent mass-spring model. Subsequently the bifurcation diagram has been depicted using the obtained fixed point. The static pull-in voltage value for different values of angular velocity and the static pull-in angular velocity for different values of bias voltage have been calculated. The obtained results are validated using results of previous studies and a good agreement has been observed. The effect of the centrifugal force on the fixed points has been studied using the phase portraits of the system for different initial conditions. Moreover, the effects of centrifugal forces on the dynamic pull-in behavior have been investigated using time histories and phase portraits for different angular velocities.

The supersymmetric quantum mechanics theory and Darboux transformation for the Morse oscillator with an approximate rotational term

Anharmonic potentials with a rotational terms are widely used in quantum chemistry of diatomic systems, since they include the influence of centrifugal force on motions of atomic nuclei. For the first time the Taylor-expanded renormalized Morse oscillator is studied within the framework of supersymmetric quantum mechanics theory. The mathematical formalism of supersymmetric quantum mechanics and the Darboux transformation are used to determine the bound states for the Morse anharmonic oscillator with an approximate rotational term. The factorization method has been applied in order to obtain analytical forms of creation and annihilation operators as well as Witten superpotential and isospectral potentials. Moreover, the radial Schrodinger equation with the Darboux potential has been converted into an exactly solvable form of second-order Sturm–Liouville differential equation. To this aim the Darboux transformation has been used. The efficient algebraic approach proposed can be used to solve the Schrodinger equation for other anharmonic exponential potentials with rotational terms.

Low Stress MEMS Delay Mechanism

For the existing symmetry Z-tooth MEMS delay mechanisms can not play sports in place under the influence of centrifugal force, this paper presents an asymmetric Z-tooth delay mechanism which can works reliably by weak environmental forces. Working principle and the stress condition of the mechanism are analyzed. Based on the dynamic model, this paper makes a computational analysis and simulation about the kinetic characteristics of the asymmetric Z-tooth delay mechanism, and the results show that the improved mechanism can works reliably and meets the requirements.

Gas–Liquid Sensible Heat Transfer in Spray and Packed Bed under a Centrifugal Field

Sensible heat transfer rates between a heated liquid (dibutyl phthalate) and an air stream in direct contact have been studied in different contactor configurations (spray, spray with liquid redistribution, and packed bed) wherein the liquid flows under the influence of centrifugal force rather than terrestrial gravity as in traditional equipments. Experiments were carried out by contacting the phases counter-currently between two coaxial circular rotating disks. The cooling range of the liquid in these contactors was obtained by varying mass flux of liquid and air, and the rotational speed between 0.35 and 0.67 kg/m2·s, 0.26 and 0.52 kg/m2·s, and 300 and 900 rpm, respectively. The cooling range in the spray mode of operation increased with rotational speed. The ratio of the cooling range obtained in rotating packed bed and spray operation decreased at higher rotational speed (other conditions remaining same). Below a critical rotational speed, the cooling range in spray operation could be further extende...

Influence of Centrifugal Force on Characteristics of Turbine Shaft for Micro-Spindle for Micro-Cutting

The centrifugal force has great influence on characteristics of the turbine shaft. The changes of stress, diameter and natural frequency of the turbine shaft for self-developed micro-spindle for micro-cutting following with the rotational speed were studied by finite element (FE) simulation, which showed that stress, diameter of the turbine shaft and frequency of torsional vibration in elastic shaft coupling integrated with the turbine shaft caused by the centrifugal force increases almost linearly with increase of rotational speed and the higher the speed, the larger the increase. The frequencies of other vibrational modes were influenced by centrifugal force. Materials with good properties can improve characteristics of turbine shaft caused by the centrifugal force well.

The study of the influence of centrifugal force on flow of non-newtonian fluid in the conical annular channels

Рассмотрено течение аномально-вязких жидкостей в конических кольцевых каналах при условии вращения одного из конусов. Опыты проведены с 5% водным раствором натриевой соли карбоксилметилцеллюлозы (КМЦ). Получены экспериментальные результаты, которые дают возможность составить расчетные аналитические зависимости для определения потерь давления

Influence of centrifugal forces on the operation of HSK couplings

276 The introduction of highspeed cutting at manu� facturing plants is associated with the appearance of new spindle-mandrel couplings, replacing the tradi� tional coupling characterized by a 7 : 24 tool taper. The new couplings include the HSK coupling, which is the standard in the European Community; the Coromant Capto coupling, produced by Sandvik Coromant (Sweden); and the 3lock system produced by Nikken (Japan). Most manufacturers of highspeed spindles focus on HSK couplings. In Russia, for historical rea� sons, there has been little study of HSK couplings, although the corresponding standards were promul� gated in 2000-2001.

Free Surface Thin Layer Flow in Bearings Induced by Centrifugal Effects

To be able to predict service life of grease-lubricated bearings, it is of major importance to be able to predict the grease life; i.e., to predict when the lubricant film formation capability has decreased below a certain level. The objective of the present study is to develop theoretical models that can be used in practice to predict different aspects of grease life. As a first step, the influence of centrifugal forces on lubricant migration and the long-term film thickness decay rate due to this effect in a bearing is studied. The authors present a model that can be used to predict the decrease of oil-layer thickness due to centrifugal forces as a function of position across the track for different types of bearings. It is assumed that the oil layers in each of the roller raceway contacts separate equally between the diverging surfaces. To provide some justification for this hypothesis, a roller/plate experiment is carried out. As an example, the model is applied to the geometry of a spherical roller bearing. Two flow types are distinguished, depending on the shape of the lubricated surfaces. For various sizes and for different geometry parameter settings, similar central layer decreases are predicted. It is shown that the centrifugal effects can significantly reduce the layer thickness, within the service life of the bearing.