In this work, the flexible rotor balancing problem based on the influence coefficient method and holospectrum technique is formulated as a minimax optimization problem. Details of the software products used to create this pdf file can be found in the general info relative to the file. Research article a new method for fieldbalancing of high. This part of iso 1940 does not cover rotors in a flexible state. Rotor balancing methods and instrumentation springerlink. Thirty years ago it was primarily still part of the skilled trade and was often obscured. Yet in many cases, balancing may be the chosen course of action for lowering vibration amplitudes even though it is not the source of vibration. The impact of shop balance technique is most important when the rotor is relatively flexible andor long as is common with most turbomachinery. Active balancing of flexible rotors using strain actuators. The rotor core includes an annular section, a first pole, and a second pole. Balancing of flexible rotor with bow using transfer matrix. Professor emeritus mechanical and aerospace engineering former director, rotor dynamics laboratory, univ. This thesis is dedicated to the research of flexible rotor balancing techniques, and aims to apply some advanced techniques to the field of highspeed rotor balancing. A flexible rotor is a component or machine that has significant bending during operation.
The second critical speed can sometimes be seen in the balancing pit between 3000 and 3600 rpm. The flexible rotor continually changes its elastic configuration as more critical speeds are encountered, and additional balance planes may be required. In this context satisfactory running means that not more than an acceptable magnitude of vibration is caused by the unbalance remaining in the rotor. This document does not cover the balancing of rotors with flexible behaviour. Contact sulzer for highspeed or atspeed balancing by our experienced technicians and engineers. This method includes aspects of both the modal and influence coefficient methods. This paper describes a flexible rotor system used for twoplane laser balancing and an experimental demonstration of the laser material removal method for balancing. The aim of balancing any rotor is to achieve satisfactory running when installed on site. Active balancing of flexible rotors using strain actuators arthur w.
What is the difference between a rigid and a flexible rotor. Dynamic balancing of supercritical rotating structures using. What is difference between rigid and flexible rotor. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. Introduction the international standards organization, iso, published standard 19401 balance quality requirements of rigid rotors, which has been. Dynamic analysis and field balancing of 100 mw utility gas. An introduction to a unified approach to flexible rotor. Mechanical vibration methods and criteria for the mechanical balancing of flexible rotors see other formats disclosure to promote the right to information whereas the parliament of india has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities. The stateofart for flexible rotor balancing is summarized, and the work which remains is identified. This measurement is not needed for balancing the rotor, but will be used later as a check on. In the case of a flexible rotor, it also means that not more than an acceptable magnitude of deflection occurs in the. Among the broad ranges of faults that cause synchronous v. I he balancing procedure tor flexible rotors is more complicated, because of the elastic deflections of the rotor. Liu 2005 described a balancing technique for flexible rotor based on holospectrum.
Finally, a comparison of various balance quality grades is made with milstd1671 and api balance limits. For overhung rotors, or with sufficient reasurelllent and balance planes located along the rotor, rctors in rigid bearings aay be readily balanced. Every rotor has an individual unbalance distribution along its length, even in series production. These strain actuators would be arranged in a bimorph con. Rotordynamics and balancing revisited balancing of. The balancing of flexible rotors on bearing supports is considered from fundamental and practica. Rotating machinery rotor balancing lifetime reliability. Ny nasa contractor report 2975 balancing techniques for highspeed flexible rotors a. Recent developments toward the establishment of criteria for appropriate levels of residual unbalance in flexible rotors following balancing operations are included. Application notes static and dynamic balancing of rigid. For such cases, low speed balancing can satisfy all balancing requirements. The test is carried out at service speed either in the rotor service bearings or in a highspeed, hardbearing balancing machine. The controversy between modal and influence coefficient methods began.
Dynamic balancing of rotating machinery experiment technical advisor. Flexible rotor balancing is significantly more complex than rigid rotor balancing. Active balancing of flexible rotors using strain actuators 485 example smas or piezoelectric patches. The problem is actual for the highspeed rotors working at supercritical speeds rotors of aircraft engines, gas turbine engines of power plants, etc. To investigate unbalance on a rigid rotor, a laboratory test was done on an unbalanced rigid rotor and both static and dynamic balancing procedures were performed on the rotor. The balance quality requirements for rotors in a flexible state are covered by iso 142. The incremental rotor balancing procedure turbomachinery. In some cases, these faults will produce other symptoms that can suggest corrections other than balancing should be done. May 28, 2017 the methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor.
Despite of the development of various methods of flexible rotor balancing, most problems with difficult to balance rotors, whether in the factory environment. The conditions for the occurrence of autobalancing when balancing a flexible axisymmetric rotor by any number of passive autobalancers of any type are determined. This test serves to determine if a rotor may be considered rigid for balancing purposes or if it must be treated as a flexible rotor. Investigation of the influence coefficient method for. Pdf practical balancing of flexible rotors for power. Do you need balancing services for turbine, compressor and generator rotors up to 200,000 lbs 62. A balancing method known as lowspeed holo balancing was developed, which could balance a flexible rotor without test runs at high speeds. Balancing of rotors, hard or soft the combination of the rotor length and the rotor weight gives in our cases a stiff rotor with only the first critical speed visible on site during the start up and shutdownthe start up and shutdown. A rotor balancing system is provided that includes a rotor core, a plurality of core channels, a support wedge, a wedge channel, and balance masses. Rotordynamics and balancing revisited balancing of large. The majority of balancing is done on any common, highspeed balancing machine at not higher than 50%. These generic titles refer to whether or not rotor flexibility is taken into account.
Research article a new method for field balancing of highspeed flexible rotors without trial weights y. Research article a new method for fieldbalancing of highspeed flexible rotors without trial weights y. Establishing balancing tolerances for rigid rotors it is neither practical nor possible to remove all unbalance of a rotor. Rotor balancing methods may be separated into two categories. In the case of a flexible rotor, it also means that not more than an acceptable magnitude of deflection occurs in the rotor at any speed up to the maximum service speed.
A threemass test rotor with a flattened shaft was designed to evaluate the feasibility and problems of. Practical balancing of flexible rotors for power generation. Classifies rotors into groups according to their balancing requirements, establishes assessment methods for final unbalance, and gives initial guidance on the establishment of balance quality grades so that, ultimately, balance quality grades can be established for all types of flexible rotors. That is, flexible rotor balancing procedures take into account rotor flexibility, while rigid rotor balancing procedures do not. If it is operating below that speed it is considered rigid. Single rotor system placed on two parallel horizontal knife edges allowed to roll freely until it comes to rest static imbalance is signified by the rotor settling to rest at the same location mass can be added or removed to removed the imbalance. Rotor balancing turbine applied and interdisciplinary.
Rieger, verbatim the need for flexible rotor balancing procedures emerged in the post world war 2 period, due largely to the rapid increase in the size of the rotating equipment used in the power generation, chemical processing, and aircraft turbine industries. The procedure utilizes measured runout eccentricities and femodeled rotor mode shapes for the selection of balancing planes. Advanced field balancing concepts kelm engineering. It means no more than an acceptable magnitude of vibration is caused by the unbalance remaining in the rotor.
Flexible rotor a flexible rotor might be defined as a rotor which runs above a flexible rotor critical speed or within 25 percent below that speed. A balancing method known as lowspeed holobalancing was developed, which could balance a flexible rotor without test runs at high speeds. This paper proposes a novel balancing method of flexible rotors, which does not require the machine to be rotated at high speeds. Balancing is a procedure in which the mass distribution of a rotor is checked and, if necessary, adjusted. That, if we have the rotor on balance, irrespective of nature rigid or flexible, it has a clear impact on the vibration generations in the entire machines. Balancing techniques for highspeed flexible rotors ntrs nasa. The article contains excerpts from the paper, rotor balancing tutorial by ray kelm, dustin pavelek and walter kelm of kelm. Note in iso 2194014, the assessment of balancing errors is considered in detail. The first and second poles each extend radially outwardly from the annular section and form an interpole region therebetween. A rigid rotor can be balanced at the two end planes and will stay in balance when in service. An introduction to a unified approach to flexible rotor balancing. The bearing vibration is usually large and can be rectified by using normal balancing methods. The change in speed affects the centrifugal force, causing bending and twist effects to.
This in turn causes a significant reduction of stiffness and particularly of damping. Pdf practical balancing of flexible rotors for power generation. Balancing of flexible rotors with optimization methods. Laser balancing demonstration on a highspeed flexible rotor. Tool balancing theory rotor unbalances can be caused by design, material, manufacturing and assembly. A flexible rotor will require multiplane balancing. We must establish balancing tolerances that are economically feasible and still low enough to provide satisfactory operation. The objective was to apply the theory of rotor balancing, gain skills on rotor balancing and get to know how to operate the balancing machine. Shop balancing methods the methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor. Flexible rotor a flexible rotor might be defined as a rotor which runs above a flexible rotor critical speed. Balancing is the method to eliminate the imbalance. Rotor unbalance is a basic concern in the design and operation of machinery because it is a major cause of excessive vibration.
Synchronous lateral vibration is a frequent cause of machine failure and is probably the most common source of machine noise and vibration. Ideally, in the operation of all rotating machinery, the inertia axis of. An early flexible rotor balancing technique, was based on mode shapes modal method. Apr 24, 2015 this paper describes a flexible rotor system used for twoplane laser balancing and an experimental demonstration of the laser material removal method for balancing. Fundamentals of rotor balancing are contained in iso 19499 which gives an introduction to balancing. Rotor balancing is a fundamental requirement for the smooth operation of turbomachinery. Rajiv tiwari,department of mechanical engineering,iit guwahati. Dynamic analysis and field balancing of 100 mw utility gas turbine generators edgar j. Whether or not a rotor is classified as rigid or flexible depends on the relationship between the rotating speed rpm of the rotor and its natural frequency. Dynamic balancing of rotating machinery experiment technical. This bending can be seen when there is a change in speed. This measurement is not needed for balancing the rotor, but will be used later as a check on calculations. In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them.
Mechanical vibration methods and criteria for the mechanical balancing of flexible rotors by bureau of indian standards. The methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor. Moore demonstrated the practical application of the method to heavy rotating equipment. If a rotor is balanced on a low speed balancing machine assuming it is rigid and then in service becomes flexible, then unbalance and thus high vibration, will be the result. A new method for fieldbalancing of highspeed flexible. Friswell college of engineering, swansea university, bay campus, fabian way, crymlyn burrows, swansea sa1 8en, uk.
If a rotor is balanced on a low speed balancing machine assuming it is. Rotors are seen everywhere, its seen on electric motors, in engine parts, big machines, pully systems etc, etc rotors while rotating will create vibration due to lot of reasons, in short any unbalanced force acting on these rotors while rotati. Methods of balancing of an axisymmetric flexible rotor by. The rotor should first be balanced fairly well at low speed. A rigid rotor can be balanced by making cor rections in any two arbitrarily selected i rnr u i a. Latham, new york prepared for lewis research center under contract nas318520. Balance quality requirements of rigid rotors ird balancing. Significant progress in balancing methods for flexible rotors can be achieved by the improvement and optimization of existing balancing techniques. Rotating machinery rotor balancing the aim of rotor balancing is to achieve satisfactory running when installed on site. Detailed consideration of errors associated with balancing and verification of residual unbalance are given in iso 19402. The article contains excerpts from the paper, rotor balancing tutorial by ray kelm, dustin pavelek.
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