MICROSTRUCTURE AND MACROSEGREGATION OF Al-7%Si ALLOY SOLIDIFIED UNDER COMPLEX EFFECTS OF ELECTROMAGNETIC AND CENTRIFUGAL FORCES

Macrosegregations and microstructures of Al-7%Si alloy solidified under complex of fects of magnetic field and centrifugal forces are studied by means of a set of selfdesigned electromagnetic centrifugal casting (EMCC) device. It is shown that electromagnetic field (EMF) has an important effect on the macrosegregation of centrifugal casting specimen of Al-7%Si alloy in two respects: one is that there exists always a kind of convection in the liquid in front of the S/L interface caused by effect ofthe electromagnetic force; the other is that different atomic clusters of solidparticles with different physical characteristics are subjected to quite different electromagnetic (Lorentz) force. Therefore, their movements get changed. In addition, the formation process of a complex band structure consisting of primary α-Al dendrites and (α-Al+β-Si) eutectics in hypoeutectic Al-Si alloys during EMCC and the effect of EMF are discussed.

Multi-Field Analysis and Experimental Verification on Piezoelectric Valve-Less Pumps Actuated by Centrifugal Force

A piezoelectric centrifugal pump was developed previously to overcome the low frequency responses of piezoelectric pumps with check valves and liquid reflux of conventional valveless piezoelectric pumps. However, the electro-mechanical-fluidic analysis on this pump has not been done. Therefore, multi-field analysis and experimen- tal verification on piezoelectrically actuated centrifugal valveless pumps are conducted for liquid transport appli- cations. The valveless pump consists of two piezoelectric sheets and a metal tube with piezoelectric elements pushing the metal tube to swing at the first bending resonant fre- quency. The centrifugal force generated by the swinging motion will force the liquid out of the metal tube. The governing equations for the solid and fluid domains are established, and the coupling relations of the mechanical, electrical and fluid fields are described. The bending res- onant frequency and bending mode in solid domain are discussed, and the liquid flow rate, velocity profile, and gauge pressure are investigated in fluid domain. The working frequency and flow rate concerning different components sizes are analyzed and verified through experiments to guide the pump design. A fabricated pro- totype with an outer diameter of 2.2 mm and a length of 80 mm produced the largest flow rate of 13.8 mL/min at backpressure of 0.8 kPa with driving voltage of 80 Vpp. Bysolving the electro-mechanical-fluidic coupling problem, the model developed can provide theoretical guidance on the optimization of centrifugal valveless pump characters.

Flow Field of Metallic Fluid Acted by Electromagnetic and Centrifugal Force

According to the principle of electromagnetism and hydrodynamics,a mathematical model of flow field for metallic fluid acted by electromagnetic and centrifugal forces was established.The calculation results showed that the relative velocity between metallic fluid layers rises and the absolute rotational velocity of metallic fluid falls with the increase of magnetic induction intensity.The increase of centrifugal revolution hardly affects the relative velocity between metallic fluid layers,but can enhance the absolute rotational velocity of metallic fluid.

STOCHASTIC BOUNDARY ELEMENT METHODS FOR 3－D PROBLEMS WITH CENTRIFUGAL FORCES AND RELIABILITY ANALYSIS

A stochastic boundary element method (SBEM) is developed for 3-Dproblems with body forces. The integral equations of SBEM are established by the approach of partial derivation with respect to stochastic variables, considering the strengthlimit, rotation speeds and material density to be the fundamental stochastic variables.The method developed is applied to analyzing the strength reliability of the turbo diskof an aero-engine.

The Influence of Centrifugal Force on the Interference Fit of High-Speed Electric Spindle

The letter presents an analysis of interference fit of the electric spindle at different rotor speeds due to the influence of centrifugal force and provides a theoretical formula showing the relationship of the speed, stress on the rotation speed. The letter also established a finite element model of the interference fit. The study found that as the rotation speed increases, the interference and contact stress between the spindle and the rotor gradually decrease, and the reduced speed is proportional to the square of the rotation speed.

The Gravitomagnetic and Field Magnetic Centrifugal Force Using Force and Four-Dimensional Potential Concepts

Unification of fundamental forces is the dream of physics. Nevertheless, unfortunately gravitational force operators to be isolated in its geometrical content from other forces. This encourages some researchers to propose the so-called gravimagnetic field to unify gravity with other forces and to explain some cosmological problems at the early universe. This motivates to construct a new model to confirm the existence of gravitomagnetic and a corresponding magnetic field associated with any field. Using the formal Newton definition of force and considering the magnetic force to be related to the time varying mass, the magnetic force is shown to be equal to the centrifugal force. This equality is typical when treating a particle as string. Using also the definition of force in terms of potential and electric force only, energy is shown to be conserved. The Newton force can be defined also in terms of four-dimensional potential with the time varying part related to the magnetic potential. When the particle is treated as a string, energy conservation holds, while for ordinary particle, the Lagrangian is conserved. The energy conservation holds for special relativity also for energy per unit mass. The definition of acceleration for forces that obeys inverse square law shows also the magnetic force is equal to the centrifugal force.

A Comparative study on generalized Manev potential and Newtonian potential in perturbed restricted four-body problem

The motion of a test particle within the context of the restricted four-body problem(R4BP)driven by a new kind of potential,called the generalized Manev potential,with perturbations in the Coriolis and centrifugal forces is considered in this study.The system possesses eight libration points which were distributed on its plane of motion in different manner from those of the usual Newtonian potential.Unlike the case of the perturbed R4BP under Newtonian potential,where two of these librations are stable,all of them are unstable in linear sense under Manev potential.We found that a gradual perturbation in the centrifugal force causes the trajectories of motion to drift inward but the Coriolis force was proven to have no effect on the location of the libration points of the system.Using first order Lyapunov characteristic exponents,the dynamical behavior of the system is found irregular.We experimented with a high velocity stellar system(82 G.Eridani)to establish the applicability of the model in astrophysics.

The Effect of Body Pitching on Leg-Spring Behavior in Quadruped Running

In this paper we investigated how the running speed would affect the dynamics of body pitching, and whether body inertiais important for animals. Passive trotting of spring-mass model and passive bounding of spring-beam model were studied atdifferent speeds for different sets of body parameters respectively. Furthermore, different body inertias were used in bounding.We found that running speed exerts effect on leg performance by means of centrifugal force. The centrifugal force can be understoodas an enhancement to the natural frequency of the spring-mass system. The disadvantage of body pitching may beoffset by the great increase in centrifugal force at high speed. The results also reveal that body mass distribution might not be themain reason for the difference in maximal running speeds of different animals.

Numerical Investigation of Submarine Hydrodynamics and Flow Field in Steady Turn

This paper presents numerical simulations of viscous flow past a submarine model in steady turn by solving the Reynolds-Averaged Navier-Stokes Equations（RANSE） for incompressible, steady flows. The rotating coordinate system was adopted to deal with the rotation problem. The Coriolis force and centrifugal force due to the computation in a bodyfixed rotating frame of reference were treated explicitly and added to momentum equations as source terms. Furthermore, velocities of entrances were coded to give the correct magnitude and direction needed. Two turbulence closure models（TCMs）, the RNG k-ε model with wall functions and curvature correction and the Shear Stress Transport（SST） k-ω model without the use of wall functions, but with curvature correction and low-Re correction were introduced, respectively. Take DARPA SUBOFF model as the test case, a series of drift angle varying between 0° and 16° at a Reynolds number of 6.53×10^6 undergoing rotating arm test simulations were conducted. The computed forces and moment as a function of drift angle during the steady turn are mostly in close agreement with available experimental data. Though the difference between the pressure coefficients around the hull form was observed, they always show the same trend. It was demonstrated that using sufficiently fine grids and advanced turbulence models will lead to accurate prediction of the flow field as well as the forces and moments on the hull.

Investigation of Working Bodies of the Device for Separation of Fibers Suitable for Spinning from Cotton Waste

It is known that fiber wastes (lint, down and seeds) produced at ginneries contain fibers that are suitable for spinning and can be used in industry, and their separation significantly increases the level of fiber production (1.9% - 2.5%). Based on these analyzes, the study aimed to create a new device that separates long fibers from lint and down. As a result, the amount of fiber output in the enterprise will increase and the enterprise will have significant economic benefits. In addition, the introduction of the device will prevent the addition of long fibers (longer than 16 mm) that can be used in the textile industry to the waste. This article focuses on the creation of a fiber separation device suitable for the treatment and spinning of fibrous waste produced in ginneries. The study theoretically examined the main working bodies of the fiber separation device from waste. Theoretical research is devoted to the study of the strength of the main working body of the fiber separation device−the separating saw drum and its shaft. In the study, the sawdust drum is a more stressed steel coating, and it was found that the strength reserve of this drum is [δТ] = 2.03 (where δТ = 0.8 - 2.5) was found to be. As a result of calculating the resistance of the saw drum shaft to stiffness and vibration, it was determined that the shafts are resistant to vibration under periodic loading and that the oscillation frequency along its axis through the critical rotation frequency is vcr=10.3 Gts.

Optimization Conditions of Wheat Mesophyll Protoplast Isolation

The research object of this study is “ML7113” wheat leaf, which is used to isolate protoplast with enzyme hydrolysis method. Three main effectors—the concentration of mannitol, enzymolysis time and centrifugal force, affect the production and vitality of protoplast. While the production and vitality of wheat protoplasts were detected by the hemacytometer and the FDA staining respectively. Results showed that, with the increasing concentrations of mannitol during 0.2 M - 0.4 M, protoplast yield increases and when the concentration is 0.4 M, the protoplast vitality can be up to 95%;with the extension of enzymolysis time in 2 h to 8 h, protoplast yield reaches a maximum in 6 h, but its vitality achieves the maximum in 4 h;considering a combination of these two factors impacting on protoplast, we obtain the best time to digest for 4 h;meanwhile, with the increasing of the centrifugal force from 500 rpm - 2000 rpm, its comprehensive effect of protoplast vitality and yield is the highest when the centrifugal force is 1000 rpm for 2 min (replicated three times). So 0.4 M mannitol, 4 h enzymolysis time and 1000 rpm for 2 min centrifugal force are the best separation condition.

On the Physics inside a Closed,Static,Rotating Einsteinian Hypersphere in Due Consideration of the Galaxy

Einstein’s weak equivalence principle suggests that gravity and acceleration (centrifugal force) are indistinguishable from each other and, therefore, equivalent. We maintain that they are not only equivalent, but even identical, or to rephrase the main statement of this work: A gravitational force does not exist. Rather, gravity is a fictitious force, or, more pointedly: Gravity is the centrifugal force which acts upon material bodies within the rotating S3-hypersphere of the Universe. These in turn warp the adjacent space-fabric, shaping it to the well-known field geometry of general relativity.

Decarburization of Fe-C Melt by Pressured Oxygen

According to the principle of electromagnetism and hydrodynamics, a mathematical model of flow field for metallic fluid acted by electromagnetic and centrifugal forces was established. The calculation results showed that the relative velocity between metallic fluid layers rises and the absolute rotational velocity of metallic fluid falls with the increase of magnetic induction intensity. The increase of centrifugal revolution hardly affects the relative velocity between metallic fluid layers, but can enhance the absolute rotational velocity of metallic fluid.

Determination of Technological Parameters of Fiber Separation Device from Cotton Waste

This article examines the technological parameters of the device for the separation of fibers suitable for spinning by processing fibrous waste from the technological processes of ginneries. Technological processes in the cotton ginning industry include a complex of physical and mechanical advantages, the successful study of which is possible only with the use of modern achievements in science and technology. Therefore, it is advisable to conduct scientific research based on mathematical modeling. To justify the effective operation of the selected design of the cotton fiber separation device, it is necessary to select its optimal technological parameters. Improving the efficiency of the process of separation of spinning fibers from the composition of fibrous waste depends directly on technological parameters. The application of mathematical methods in the planning and conduct of research allows for determining the individual effects of the interaction of several factors that characterize the combined parameters of the optimization parameters, in contrast to traditional computational methods of research. As a result, it will be possible to obtain a mathematical model of the object understudy in a relatively small number of tests, which will simultaneously serve to obtain optimal solutions.

Pivotal Role of Spin in Celestial Body Motion Mechanics: Prelude to a Spinning Universe

This is the final article in our series dealing with the interplay of spin and gravity that leads to the generation, and continuation of celestial body motions in the universe. In our prior studies we focused on such interactions in the elementary particles, and in the celestial bodies in the solar system. Foremost among the findings was that, along with gravity, matter at all levels exhibits axial spin. We further noted that all freestanding bodies outside our solar system, including the largest such units, the stars and galaxies also spin on their axes. Also, the axial rotation speed of planets in our solar system has a linear positive relationship to their masses, thus hinting at its fundamental and autonomous nature. We have reported that this relationship between the size of the body and its axial rotation speed extends to the stars and even the galaxies. Next, all congregations of matter spin on their axes in the counterclockwise direction;all satellites orbit their mother bodies also in the counterclockwise direction, i.e.: in our solar system, with only rare exceptions, the satellite bodies follow the mother bodies’ axial rotation. This relationship exists also in the case of the rings of planets, the asteroids and the Kuiper belt bodies, as well as the stars and their galaxies. We also noted the intricate involvements between spin and gravity in the exquisite phenomena of synchronous and negative rotations of planets and some satellites;we have explained in detail how these two phenomena occur. The closest large moons of the gas and ice giants and the earth’s moon exhibit synchronous rotation. In this paper we present evidence that these synchronously rotating satellite bodies’ axial rotation speed is closely related to the size and the axial rotation speeds of their respective mother bodies. In the satellites that follow a non-synchronous rotation (most of the planets and their satellites) the satellites’ own rotation speed usually dominates. In all these rotational/orbital motions, we believe, the axial rotation and gravity collaborate with the resultant centrifugal force, which prevents the satellite bodies from crashing into the mother bodies. We have inferred from the above observations that the axial spin is a fundamental property of matter, akin to gravity, electromagnetism, and strong and weak nuclear forces. This inherent property of matter to spin on its axis is what initiates all celestial body motions and makes such motions perpetual. The lateral motions of stars within the galaxies, are also influenced by the sizes of the stars;the larger the star, the faster it moves radially. Similarly, the larger the spiral galaxy, the faster it rotates on its axis. We extrapolate from these observations that the axial rotational speeds of galaxies affect their motion in space as well, that this is circumferential, and we predict this will also be in the counterclockwise direction. This lateral movement of the galaxies will give the appearance of the whole universe spinning on its axis.

The Effects of Washing Conditions on the Coccidian Oocyst Collection in Chicken Manure

To optimize the production process of occidium vaccine and provide the basis and methods for the production of live vaccine,this experiment uses the collected liquid with different centrifugal forces and centrifugation time,to measure and compare the recovery,purity,collection time and costs of coccidian oocyst,for the purpose of exploring the impact of washing conditions on coccidian oocyst collection in chicken manure.The results show that for the centrifugal machine with the radius of 17.2 cm,the best washing centrifugal rotational speed is 2500 rpm /min,that is,the best washing centrifugal force RCF = 1201.85 g,and the centrifugation time is 12 min.

THE PERTURBATION SOLUTIONS OF THE FLOW IN A ROTATING CURVED ANNULAR PIPE

WT5”BZ]In this paper, the flow in a rotating curved annular pipe is examined by a perturbation method. A second order perturbation solution is presented. The characteristics of the secondary flow and the axial flow are studied in detail. The study indicates that the loops of the secondary flow are more complex than those in a curved annular pipe without rotation and its numbers depend on the ratio of the Coriolis force to centrifugal force F. As F≈-1, the secondary flow has eight loops and its intensity reaches the minimum value, and the distribution of the axial flow is like that of the Poiseuille flow. The position of the maximum axial velocity is pushed to either outer bend or inner bend, which is also determined by F. [WT5”HZ]

Vibrational characteristics of rotating soft cylinders

Rotating structural components are omnipresent in engineering structures and natural world. This work investigates the effects of the centrifugal and Coriolis forces on the free vibrational characteristics of soft cylinders rotating with respect to the axis of symmetry based on the nonlinear elasticity and linear incremental theories. The formulations indicate that the biasing deformation, instantaneous elastic moduli, and incremental equations of motion strongly depend on the rotating speed. The characteristic equation for the natural frequency is derived using the state-space method and approximate laminate technique.The numerical examples included in this work demonstrate that the centrifugal and Coriolis forces might have significant effects on the vibrational characteristics of the cylinder. Results of this work will benefit the design and control of novel engineering systems with rotating soft cylinders or shafts.

Effect of windage heating on a micro high-speed rotor-stator cavity

The main objective of this work is to investigate the effect of windage heating on the micro high-speed rotor-stator cavity.The influences of centrifugal force and spacing on the windage heating are analyzed with and without the change of gap ratio respectively.The results demonstrate that there is no difference in the flow structure between micro and large-scale rotorstator cavities at the same rotational Reynolds number and gap ratio.However,the windage heating induced by the larger centrifugal force and smaller spacing brings the different heat transfer laws for the micro rotor-stator cavity.The larger centrifugal force weakens the local heat transfer near the rotor periphery.Such influence can be strengthened at higher rotational Reynolds numbers and lower rotor excess temperatures.Besides,the smaller spacing further enhances the windage heating and reduces the average heat transfer especially under the condition of lower gap ratio.The findings of this work contribute to the design of rotor-stator cavity utilized in the micro rotating machinery.

Computational research on film cooling under rotating frame by an anisotropic turbulence model

A new anisotropic k-o turbulence model was proposed in this paper.This new model,with the standard k-o model and the standard k-e model was embedded in our three-dimensional(3-D)Navier-Stokes code to compute rotational film cooling.In addition,the theoretical and numerical analysis on the influence of the Coriolis and buoyancy forces induced by the rotation was discussed in detail.Major findings of this study are as follows:⑴The new anisotropic k-o model preformed much better compared to its isotropic counterparts.(2)In the region of 6D-12D downstream the film hole,the numerical results of the new model were much closer to the experimental data than that in the region of 0-6D.(3)The constant density term can be balanced by the pressure gradient and would not influence the velocity and temperature distributions.But the centrifugal buoyancy force and the Coriolis force would change the trajectory of cooling air and temperature distributions.