Stationary Rotation of the Partially Liquid-Filled Unbalanced Rotor under External Friction Force Action

2014 ◽  
Vol 1040 ◽  
pp. 903-906 ◽  
Author(s):  
E.N. Pashkov ◽  
Nikita Martyushev ◽  
Pavel G. Yurovsky
Keyword(s):  
Rotation Speed ◽  
External Friction ◽  
Design Parameters ◽  
Mathematical Research ◽  
Rotating Shaft ◽  
Critical Rotation ◽  
Unbalanced Rotor ◽  
Liquid Type ◽  
Critical Rotation Speed ◽  
Automatic Balancing

Rotor rotation with liquid layer on the chamber wall under viscoelastic action of the shaft within a planar model is examined in the article. The solution to the problem of determining the deflection of a rotating shaft with liquid filled chamber is given, which is important when designing an automatic balancing device. The issue of the cooperative motion of a solid body and liquid is considered in mathematical research. The set task is performed by applying D'Alembert's principle. The modeling results indicate that an increase in liquid’s mass in a rotor decreases its critical rotation speed; at the same time, the external friction accelerates the system’s self-centering. The developed mathematical models enable us to select the design parameters of a liquid-type autobalancer which operates within the set range of rotor’s angular velocity.

Efficiency of Balancing by Liquid-Type Automatic Balancing Devices

2014 ◽  
Vol 1040 ◽  
pp. 858-863 ◽  
Author(s):  
Evgeny N. Pashkov ◽  
Nikita Martyushev ◽  
Andrey V. Ponomarev
Keyword(s):  
Vibration Amplitude ◽  
Rotor Speed ◽  
Mathematical Research ◽  
Rotor Vibration ◽  
Liquid Type ◽  
Automatic Balancing ◽  
Rotor Model

The article focuses on modelling the behaviour of a liquid-type automatic balancing device. To perform mathematical research the rotor model is used that contains a ring functioning as a vessel coupled to the rigid shaft being rotatable on bearings. Data on the influence of various factors on balancing accuracy are presented. The obtained modeling results indicate that the vibration amplitude at supercritical frequencies will decrease proportionally to the increase in the parameters of a liquid autobalancer. The performed calculation also reveals that the more the parameters of a liquid autobalancing device, the higher the efficiency of balancing. Provided the condition of the liquid sufficiency in the ring is satisfied, the independence of the rotor vibration amplitude from the mass of the liquid in the vessel is achieved. Critical rotor speed does not depend on the volume of the liquid in the ring if the condition of its sufficiency is met.

scholarly journals Results from a recent stellar rotation census of B stars

2010 ◽  
Vol 6 (S272) ◽  
pp. 89-90
Author(s):  
Wenjin Huang ◽  
Douglas R. Gies ◽  
M. Virginia McSwain
Keyword(s):  
Effective Temperature ◽  
Rotation Rate ◽  
Rotation Speed ◽  
Rotational Velocity ◽  
Rotation Velocity ◽  
Be Stars ◽  
Stellar Rotation ◽  
B Stars ◽  
Critical Rotation ◽  
Critical Rotation Speed

AbstractIn an analysis of the rotational properties of more than 1100 B stars (~660 cluster and ~500 field B stars), we determine the projected rotational velocity (V sin i), effective temperature, gravity, mass, and critical rotation speed for each star. The new data provide us a solid observational base to explore many hot topics in this area: Why do field B stars rotate slower than cluster B stars? How fast do B stars rotate when they are just born? How fast can B stars rotate before they become Be stars? How does the rotation rate of B stars change with time? Does the evolutionary change in rotation velocity lead to the Be phenomenon? Here we report the results of our efforts in searching for answers to these questions based on the latest B star census.

scholarly journals SENSITIVITY OF STRENGTH, RIGID AND DYNAMIC CHARACTERISTICS OF THE CONSOLE ROTOR TO VARIATION OF DESIGN PARAMETERS

2021 ◽  
pp. 104-113
Author(s):  
Mykola А. Tkachuk ◽  
Andrey Grabovskiy ◽  
Nickolay Prokopenko ◽  
Mykola M. Tkachuk ◽  
Oleksandr Shut ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Modulus Of Elasticity ◽  
Natural Vibration ◽  
Rotation Speed ◽  
Design Parameters ◽  
Natural Vibration Frequency ◽  
Radial And Axial Displacements ◽  
Angular Velocities ◽  
Air Blower ◽  
Critical Rotation Speed

The analysis sensitivity of strength, rigid and dynamic characteristics of the console rotor to variation of design parameters in paper describes The speed of rotation of the shaft, the material of the impeller vary. The dependences of radial and axial displacements on the angular velocities of rotation and the modulus of elasticity of the impeller material are established. For objects of the type of rotary systems with a cantilever arrangement of the impeller, not one, but a set of criteria has been introduced into consideration, which should be taken into account in the research of this type of objects. The tendencies of change of the first and second critical rotational speeds from the modulus of elasticity, rotor rotational frequencies and density of the impeller material are also determined. On this basis, recommendations have been developed for determining the design parameters of the rotor part of the air blower with a cantilevered impeller. Keywords: air blower; critical rotation speed; natural vibration frequency; rotary system; stress-strain state

Critical Rotation Speed Calculation and Application Development of Multi-Stage Centrifugal Pumps for Mining

2011 ◽  
Vol 130-134 ◽  
pp. 1119-1122
Author(s):  
Wei Li ◽  
Wei Dong Shi ◽  
Xiao Ping Jiang ◽  
Yan Xu
Keyword(s):  
Rotation Speed ◽  
Computational Method ◽  
Secondary Development ◽  
Centrifugal Pumps ◽  
Operational Environment ◽  
Application Development ◽  
Critical Rotation ◽  
Multi Stage ◽  
Pump Shaft ◽  
Critical Rotation Speed

Multi-stage centrifugal pumps for mining are widely used in mining and smelting industry. The operational environment in coal mine sewage is very harsh, so pump shaft and bearing failure happens frequently. In order to avoid disaster damage caused by failure of the pump shaft due to resonance, it is quite necessary and urgent to calculate critical rotation speed of the pump shaft. A calculation program of critical rotation speed for multi-stage centrifugal pumps for mining was developed using the secondary development tool of Object ARX, to give the computational method of the pump shaft load and static deflection and to achieve calculation of the critical speed, and which avoided the disadvantage of the traditional method. The practical application indicates that the program of critical rotation speed is convenient, intuitive and calculation accurate. It not only improves the work efficiency, but also reduces the labor intensity, so the program will have a good application prospect.

Stability Control Analysis of Rotating Plates by Finite Element: Emphasis on Slots and Holes

1972 ◽  
Vol 94 (1) ◽  
pp. 64-70 ◽  
Author(s):  
C. D. Mote
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Rotation Speed ◽  
Stability Control ◽  
Control Analysis ◽  
Circular Plates ◽  
Critical Speeds ◽  
Critical Rotation ◽  
Critical Instability ◽  
Critical Rotation Speed

Accurate finite element procedures have been developed for the vibration of plates with significant membrane stresses. Thermally stressed, rotating circular plates with peripheral edge slots are examined in detail and the influence of slots upon critical rotation speed instability is clarified. In realistic environments slots can considerably increase critical speeds through the reduction of compressive thermal stresses and the introduction of geometrical assymmetry. Optimization of critical instability speeds is discussed.

scholarly journals The theoretical model for determinig critical rotation speed flexible coupling type SEGE

2018 ◽  
Vol XIX (1) ◽  
pp. 326-329
Author(s):  
Ivanova E
Keyword(s):  
Theoretical Model ◽  
Elastic Element ◽  
Radial Displacement ◽  
Rotation Speed ◽  
Impact Load ◽  
Flexible Coupling ◽  
Critical Rotation ◽  
Critical Rotation Speed ◽  
Elastic Elements ◽  
Coupling Type

It this article was studied a flexible coupling with a rubber elastic element. In exploitation period under one direction load, half of all cylinders are working. All of cylinders are made along with a carrying ring. The elastic elements are subjected to compression. On the non-loaded cylinders, a centrifugal force acts to cause their radial displacement. By the slow rubber relaxation of not loaded cylinders, in the case of reverse and impact load it is danger of can be pinched between the metal claws of semi couplings. Radial displacement and critical rotation speeds were determined, for non-loaded cylinders, in the time which is derived pinching the rubber elastic element.

INFLUENCE OF TECHNOLOGICAL FACTORS ON THE EFFICIENCY OF REMOVAL OF SCALE FROM FLATS FOR HOLLOW BALLS

2021 ◽  
pp. 143-147
Author(s):  
А.В. Панфилова ◽  
А.В. Королев ◽  
О.П. Решетникова ◽  
Б.М. Изнаиров ◽  
А.Н. Васин
Keyword(s):  
Rotation Speed ◽  
Experimental Studies ◽  
Surface Cleaning ◽  
Point Of View ◽  
Design Parameters ◽  
Technological Factors ◽  
Proportional Relationship ◽  
Sheet Products ◽  
Process Factors ◽  
Rolled Surface

Рассматриваются результаты проведения экспериментальных исследований способа удаления окалины с поверхности стального листового проката. Предложен новый способ и устройство для очистки поверхности листового проката от окалины режущими пластинами, вращающимися вокруг оси, перемещающейся поступательно вдоль обрабатываемой поверхности. Пластины наклонены в направлении вектора вращения на угол до 10 градусов и упруго поджимаются к обрабатываемой поверхности. Это обеспечивает возможность в процессе очистки поверхности воспроизводить макронеровности листового проката. Приведены результаты экспериментальных исследований, построены математические и графические зависимости, описывающие влияние факторов процесса на эффективность очистки поверхности проката. Показано, что наиболее значимое влияние на параметр оптимизации оказывает сила воздействия инструмента на поверхность заготовки. Причем это влияние реализуется в прямо пропорциональной зависимости. Другие исследованные факторы, а именно: угол наклона пластины, скорость ее вращения и подача, оказывают значительно меньшее влияние на степень очистки проката. Эти исследования были необходимы с точки зрения определения конструктивных параметров силовых элементов как технологической оснастки, реализующей указанный способ, так и технологической установки в целом. План эксперимента был принят, исходя из реальных производственных возможностей индустриального партнера, и соответствовал классическим представлениям теории резания. Описанные результаты дают возможность планировать дальнейшие эксперименты по изучению направлений использования данного способа Here we consider the results of experimental studies of the method of removing scale from the surface of steel sheet products. We propose a new method and device for cleaning the surface of rolled sheets from scale by cutting plates rotating around an axis moving translationally along the treated surface. The plates are tilted in the direction of the rotation vector at an angle of up to 10 degrees and are elastically pressed to the treated surface. This makes it possible to reproduce the macro-dimensions of sheet metal during the surface cleaning process. We present the results of experimental studies. We constructed mathematical and graphical dependences describing the influence of process factors on the efficiency of cleaning the rolled surface. We show that the most significant influence on the optimization parameter is exerted by the force of the tool's impact on the surface of the workpiece. Moreover, this influence is realized in a directly proportional relationship. Other factors studied, namely the angle of inclination of the plate, its rotation speed and feed, have a much smaller impact on the degree of cleaning of rolled products. These studies were necessary from the point of view of determining the design parameters of the power elements of both the technological equipment implementing this method and the technological installation as a whole. We adopted the experimental plan based on the real production capabilities of the industrial partner and corresponded to the classical concepts of the cutting theory. The described results make it possible to plan further experiments to study the directions of using the method

Limit-Cycle Analysis of Three-Dimensional Flexible Shaft/Rigid Rotor/Autobalancer System With Symmetric Rigid Supports

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
DaeYi Jung ◽  
H. A. DeSmidt
Keyword(s):  
Limit Cycle ◽  
Three Dimensional ◽  
Design Parameters ◽  
Rigid Rotor ◽  
Modal Shape ◽  
Flexible Shaft ◽  
Flexible Mode ◽  
Automatic Balancing ◽  
Rigid Supports ◽  
Limit Cycle Behavior

In recent years, there has been much interest in the use of automatic balancing devices (ABD) in rotating machinery. Autobalancers consist of several freely moving eccentric balancing masses mounted on the rotor, which, at certain operating speeds, act to cancel rotor imbalance. This “automatic balancing” phenomenon occurs as a result of nonlinear dynamic interactions between the balancer and rotor wherein the balancer masses naturally synchronize with the rotor with appropriate phase to cancel the imbalance. However, due to inherent nonlinearity of the autobalancer, the potential for other undesirable nonsynchronous limit-cycle behavior exists. In such situations, the balancer masses do not reach their desired synchronous balanced positions resulting in increased rotor vibration. To explore this nonsynchronous behavior of ABD, the unstable limit-cycle analysis of three-dimensional (3D) flexible shaft/rigid rotor/ABD/rigid supports described by the modal coordinates has been investigated here. Essentially, this paper presents an approximate harmonic analytical solution to describe the limit-cycle behavior of ABD–rotor system interacting with flexible shaft, which has not been fully considered by ABD researchers. The modal shape of flexible shaft is determined by using well-known fixed–fixed boundary condition due to symmetric rigid supports. Here, the whirl speed of the ABD balancer masses is determined via the solution of a nonlinear characteristic equation. Also, based upon the analytical limit-cycle solutions, the limit-cycle stability of three primary design parameters for ABD is assessed via a perturbation and Floquet analysis: the size of ABD balancer mass, the ABD viscous damping, and the relative axial location of ABD to the imbalance rotor along the shaft. The coexistence of the stable balanced synchronous condition and undesirable nonsynchronous limit-cycle is also studied. It is found that for certain combinations of ABD parameters and rotor speeds, the nonsynchronous limit-cycle can be made unstable, thus guaranteeing asymptotic stability of the synchronous balanced condition at the supercritical shaft speeds between each flexible mode. Finally, the analysis is validated through numerical simulation. The findings in this paper yield important insights for researchers wishing to utilize ABD in flexible shaft/rigid rotor systems and limit-cycle mitigation.

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