Lateral vibration of a shaft rotor is due to instability, unbalance, or other forces acting on the rotor. The high transient forces call for large bearings, but maximum allowable speed decreases as size increases for rolling element bearings. Rotor dynamics is an important branch of dynamics that deals with behavior of rotating machines. It has beam element rotordynamic example page 96127. The effect of the presence of the single transverse crack on the response of the rotor has been a focus of attention for many researchers. These types include horizontal and vertical pumps, compressors, steam turbines, motors, generators, alternators. Pdf rotordynamics introductory cristobal ponce salazar. Turbocharger bearing support and rotor dynamics bearing. A merger of all the aforementioned procedures, with the acoustic and airframe constraint interfaces.
Design and optimization work package of the cluster. This site is a gateway to technical literature on rotordynamics, including an online database of over 26,000 technical papers presented at conferences related to rotordynamics worldwide since 1974. Lateral vibration analysis vibration, dynamics and noise. With the rotor dynamics functionality now integrated into nx nastran, users can now more easily simulate rotating system loads, perform synchronous and asynchronous analysis to generate.
The latter of these options is achieved with the solid rotor interface in the rotordynamics module, which uses a 3d cad geometry to represent the rotor and solid elements for finite element modeling. By studying all of the components in a rotating assembly, you can generate the most accurate results possible. This paper presents results from experimental and analytical studies on rotor tostationary element partial rubbings at several locations and their effects on rotor dynamic responses. Nx nastran rotor dynamics applications the following is a list of common industryspecific problems that can be analyzed using the nx nastran rotor dynamics application. Rotor dynamics without equations 3 cause of this divergence is the wobbling of the noncentral disk during whirling. Turbopump rotor dynamics because of high power density and low damping in rocket turbopumps, these machines exhibit in their most extreme form a variety of vibration effects, which are either absent or masked by normal damping mechanisms in other turbo machines. Torsional vibration, synchronous and nonsynchronous whirl, stability, gyroscopic effects, hydrodynamic bearings, hysteresis, squeeze film dampers, and balancing. The stiffness of such a rotor is derived based on the concepts of. Flight applications to bo105 coupled fuselagerotor dynamics. On centrifugal softening in finite element method rotordynamics.
A merger of the rotor performance optimization with the airload dynamics optimization will yield a fully integrated aerodynamicdynamic procedure. Introduction to dynamics of rotor bearing systems includes numerous examples, from a singledegree of freedom system to complicated industrial rotating machinery, which serve to illustrate fundamental dynamic behaviors. Machinery vibration and rotordynamics pdf free download epdf. During run updown and at steady operating speeds, high levels of rotor vibration can produce very damaging effects.
Introduction and definitions rotor dynamics is the field of science that studies the response of rotating parts subjected to dynamic forces. Lateral analysis also called rotordynamics analysis simulates the rotating system, calculates the critical speeds, predicts vibration amplitudes, and provides recommendations to reduce vibration risks. The interaction of this wobbling motion with the disk angular momentum vector produces an effect that increases the fw frequency and decreases the bw frequency. Introduction equations of motion structural analysis case studies references history and scientists history and scientists 7 27 1869 ankine r on the centrifugal force on rotating shafts steam turbines notion of critical speed 1895 oppl f, 1905 belluzo, stodola notion of supercritical speed 1919 effcott j the lateral vibration of loaded shafts in the neighborhod. When designing rotating machines their dynamic characteristics must be considered to minimise the possibility of failure. Graduate standing in engineering or related discipline catalog description. Most often, they represent the lowest modes of the entire machine structure.
Conference onrotor dynamics2010 seoul,korea 1215september2010 volume1 of2 isbn. Rotor dynamcis of a centrifugal pump technical university eindhoven, february 2006 52 whirl of simple rotors in rotor dynamics a common phenomenon is whirling. Introduction to dynamics of rotor bearing systems includes numerous examples, from a singledegreeoffreedom system to complicated industrial rotating machinery, which serve to illustrate fundamental dynamic behaviors. At its most basic level, rotor dynamics is concerned with one or more mechanical structures. Rotor dynamics meaning rotor dynamics definition rotor dynamics explanation. Nonlinear coupling elementsbetween rotating and nonrotating parts oslide bearings oroller bearings osqueeze film dampers oseals ocontact model between rotating and nonrotating parts ocoupling by magnetic field oselflubricating bearing future.
Analyze a variety of rotating machines with the rotordynamics. Analysis and design of shafts for rotating machinery. Each body is considered as rigid and their equilibrium equations are similar. This fundamental rotor dynamics short course is intended for engineering staff of companies using, repairing or manufacturing rotating machinery of common types. Errata dynamics of rotating machines michael i friswell, john e t penny, seamus d garvey and arthur w lees cambridge university press, 2010, 512 pp. The rotor unbalance acts, therefore, in the lateral vibration mode, like an external exciting centrifugal force. Fundamentals of rotorbearing dynamics using dyrobes the. Fundamentals of rotorbearing dynamics and case histories.
This field is more than 140 year old and it is acquiring more attention day by day. The stiffness of such a rotor is derived based on the concepts of fracture mechanics. Fundamentals of rotorbearing dynamics and case histories in. The aim of this chapter is to elucidate a number of physical phenomena some of them counter intuitive which are typical of rotor dynamics. Also important are the dynamics of the foundation and its interaction with the dynamics of the rotor. Rotordynamics, multiphysics, modal analysis, micro. Rotordynamics, also known as rotor dynamics, is a specialized branch of applied mechanics concerned with the behavior and diagnosis of rotating structures. Next, through the supporting bearings and through the fluid encircling the rotor unless the rotor operates in vacuum, the rotor lateral vibrations are transmitted to the nonrotating parts of the machine. In the present work a simple jeffcott rotor with two transverse surface cracks has been studied. First, dynamic loads are applied as a function of time or frequency. Material properties and dimensions of a jeffcott rotor, courtesy of 3. In this section, some mathematical concepts as the shift matrix will be introduced. Next, through the supporting bearings and through the fluid encircling the rotor unless the rotor operates in vacuum, the rotor lateral vibrations are transmitted to. Pdf the centrifugal softening effect is an alleged and elusive reduction of the natural frequencies.
Rotor dynamics is the branch of engineering that studies the lateral and torsional vibrations of rotating shafts, with the objective of predicting the rotor excessive vibrations. Dynamics of multi rotor systems the aim of this document is to describe mathematically the behavior of a mechanical system composed by a stator with a different number of rotors. The rotor structural optimization is a continuation of the work of reference 12. He is a registered professional engineer in the states of texas and florida. Small rotor vibrations result in low stresses on the shaft, bearings and surrounding equipment.
It modifies the apparant stiffness of the model and can produce unstable. The unbalance response of the jeffcott rotor has been described by two second order differential equations to describe the dynamical motion of the system. Ethos energy, houston, texas 3100 south sam houston parkway e. But through all of this, one aspect of simulating rotating sys.
Abstract a number of the computer programs for rotordynamic stability and critical speed prediction in common use during. Rotating shafts this type of a rotating structure can be analyzed using two cases the symmetric case and the unsymmetric case. Modal analysis is performed to obtain the eigenfrequencies and the associated. They combine to give a stiffening net effect, causing both forward. Unique and specific problems will be presented and its solution illustrated in. Rotor dynamics by jaafar alsalaet department of mechanical engineering college of engineering university of basrah 1. It is commonly used to analyze the behavior of structures ranging from jet engines and steam turbines to auto engines and computer disk storage. The mathematical model of a rubbing rotor is given. Design audits of machineryrotor dynamics 2 vibration principles and phenomena throughout a machines operating range and life between turnarounds, maintaining small rotor vibration amplitudes is our basic desire. Fundamentals of rotor bearing dynamics and case histories in the rotating machinery industry third annual short course dates. Design audits of machinery rotor dynamics another reason rotor instability can lead to large vibrations is because the rotor s natural frequency is excited. Maslen jamesmadisonuniversity, united states, and l. Structural dynamics and vibration laboratory october 27, 2009. In order to use rotor dy namics as a tool to solve machiner y problems, one must first look at.
Turbocharger bearing support and rotor dynamics generally more favourable can be considered load orientation lop. Dec 06, 2016 the latter of these options is achieved with the solid rotor interface in the rotordynamics module, which uses a 3d cad geometry to represent the rotor and solid elements for finite element modeling. The rotating damping matrix, also depends upon the rotational velocities. Therefore, rotordynamic analysis becomes a vital tool for. When the rotor mass centerline does not coincide with its rotational axis, then mass unbalanced inertiarelated rotating forces occur.
Introduction equations of motion structural analysis case studies references outline 2 27 1 introduction. Rotor dynamics meaning rotor dynamics definition rotor dy. Two basic aspects of dynamic analysis differ from static analysis. Iftommrotordynamics2010 the8th iftomminternational conferenceon. Turbomachinery, motors, shafting, all of these industries have relied upon ansys for simulating various aspects of their devices. The concepts in the text are reinforced by parametric studies and numerous illustrative examples and figures. However, in tch with low static bearing load dynamic load component from residual unbalance prevails, which will be manifested by certain change of. Cad import and automatic meshing library of elements all analysis types including prestress dedicated postprocessing multispool dynamics simulation direct connection to bearing codes account for the flexibility of the supporting structure andor the disks. To meet the weight and the cost requirements, the present day rotors are made extremely flexible. Rotor dynamics software provides the capability to predict the dynamic behavior of rotating systems. Therefore critical speed analysis is an important part of the design procedure.
Rotor dynamics is a system level analysis unlike the vibration analysis of the individual components. Lateral rotor vibration lrv is radialplane orbital motion of the rotor spin axis. By using the upf create new elements for nonlinear rotor dynamics. Spinning up rotor dynamics by eric miller for decades, ansys software has been the dominant tool for people who make machines that spin. The gyroscopic matrix, which depends on the rotational velocity or velocities of the analysis model. There is one chapter that feels like a sales pitch for pressurised bearing but you can skim that. A machines overall reliablity depends heavily upon its underlying rotordynamic characteristics and their robustness. With this model, it was now possible to explain how a rotor could pass through a critical speed. Often it can be observed in practice, which makes this physically easy to interpret. Army on rotor dynamics and bearing design for turboshaft engines used in helicopters. Dynamics of rotating machines michael i friswell, john e t penny, seamus d garvey and arthur w lees cambridge university press, 2010, 512 pp. Rotordynamic analysis is a crucial step in the development of rotor bearing systems.
Rotor bearing solutions international rbsi ethosenergy, houston. References 9 fundamentals of elasticity references 10 energy methods 10. Each line represents the frequency spectrum at a particular rotor speed. In the analysis of the original jeffcott rotor, flexible or fluid film bearings were not considered. At the bottom of the page it is stated that, with l 1 l 2 then the semiminor and semimajor axes are given by. Description examining the diangostics of machinery diagnostics for those working with rotating machinery, this volume prepares engineers, researchers, and students for the future of rotor dynamics and bearing technology, especially pressurized bearings. Bent ley rotor dynamics research corporation minden, nevada 89423, u.
Campbell diagram of the rotor in figure 5, courtesy of 3. By studying all of the components in a rotating assembly, you. Explicit results were presented for no cavitation and for full cavitation. Following a presentation of the basic theory the dynamics of rotors supported on several bearings. Second, this time or frequencyvarying load application induces time or frequencyvarying response displacements, velocities, accelerations, forces, and stresses. A the steady state unbalance response curve shows no peak and. The two areas that can be resolved with rotor dynamics evaluation and modification are critical speed response and rotor system stability. Thus it seems natural to try to combine both bearings in a single bearing concept. The analytical studies of rotor dynamics presented in current papers usually. The rotor geometry is discretized using finite elements. Rotor dynamics is the branch of engineering that studies the lateral and torsional vibrations of rotating shaft, with the objective of predictive the rotor vibrations and containing the vibration level under an acceptable limit. Specifically, the question is for a given scatter pdf of the blade properties. There is a pdf at the attachment which is msc nastran 2016 rotor dynamics guide. Cauffman, frequencyresponse method for rotorcraft system identification.
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