Dynamic analysis and field balancing of 100 mw utility gas. Finally, a comparison of various balance quality grades is made with milstd1671 and api balance limits. If it is operating below that speed it is considered rigid. Do you need balancing services for turbine, compressor and generator rotors up to 200,000 lbs 62. Dynamic balancing of supercritical rotating structures using.
This paper proposes a novel balancing method of flexible rotors, which does not require the machine to be rotated at high speeds. What is the difference between a rigid and a flexible rotor. 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. An early flexible rotor balancing technique, was based on mode shapes modal method. For overhung rotors, or with sufficient reasurelllent and balance planes located along the rotor, rctors in rigid bearings aay be readily balanced. The balancing of flexible rotors on bearing supports is considered from fundamental and practica. These generic titles refer to whether or not rotor flexibility is taken into account. Mechanical vibration methods and criteria for the mechanical balancing of flexible rotors by bureau of indian standards. The article contains excerpts from the paper, rotor balancing tutorial by ray kelm, dustin pavelek and walter kelm of kelm. Active balancing of flexible rotors using strain actuators. The article contains excerpts from the paper, rotor balancing tutorial by ray kelm, dustin pavelek. The stateofart for flexible rotor balancing is summarized, and the work which remains is identified.
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. Rotordynamics and balancing revisited balancing of large. Significant progress in balancing methods for flexible rotors can be achieved by the improvement and optimization of existing balancing techniques. Methods of balancing of an axisymmetric flexible rotor by. The conditions for the occurrence of autobalancing when balancing a flexible axisymmetric rotor by any number of passive autobalancers of any type are determined. The balance quality requirements for rotors in a flexible state are covered by iso 142. Professor emeritus mechanical and aerospace engineering former director, rotor dynamics laboratory, univ. 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. Despite of the development of various methods of flexible rotor balancing, most problems with difficult to balance rotors, whether in the factory environment. 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. This bending can be seen when there is a change in speed. Active balancing of flexible rotors using strain actuators 485 example smas or piezoelectric patches. Tool balancing theory rotor unbalances can be caused by design, material, manufacturing and assembly. In some cases, these faults will produce other symptoms that can suggest corrections other than balancing should be done.
Thirty years ago it was primarily still part of the skilled trade and was often obscured. The rotor core includes an annular section, a first pole, and a second pole. Note in iso 2194014, the assessment of balancing errors is considered in detail. Moore demonstrated the practical application of the method to heavy rotating equipment. Rajiv tiwari,department of mechanical engineering,iit guwahati.
Establishing balancing tolerances for rigid rotors it is neither practical nor possible to remove all unbalance of a rotor. This measurement is not needed for balancing the rotor, but will be used later as a check on. Dynamic analysis and field balancing of 100 mw utility gas turbine generators edgar j. Certain other balancing techniques are also discussed. If a rotor is balanced on a low speed balancing machine assuming it is. This method includes aspects of both the modal and influence coefficient methods. Among the broad ranges of faults that cause synchronous v. Dynamic balancing of rotating machinery experiment technical advisor. Synchronous lateral vibration is a frequent cause of machine failure and is probably the most common source of machine noise and vibration.
Liu 2005 described a balancing technique for flexible rotor based on holospectrum. Flexible rotor balancing is significantly more complex than rigid rotor balancing. Ideally, in the operation of all rotating machinery, the inertia axis of. A flexible rotor will require multiplane balancing. 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. Balancing of flexible rotors with optimization methods. A threemass test rotor with a flattened shaft was designed to evaluate the feasibility and problems of. 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. An introduction to a unified approach to flexible rotor. 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. The controversy between modal and influence coefficient methods began. 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.
A flexible rotor is a component or machine that has significant bending during operation. We must establish balancing tolerances that are economically feasible and still low enough to provide satisfactory operation. Research article a new method for fieldbalancing of highspeed flexible rotors without trial weights y. 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. In the case of a flexible rotor, it also means that not more than an acceptable magnitude of deflection occurs in the. Advanced field balancing concepts kelm engineering. The test is carried out at service speed either in the rotor service bearings or in a highspeed, hardbearing balancing machine. The flexible rotor continually changes its elastic configuration as more critical speeds are encountered, and additional balance planes may be required. The second critical speed can sometimes be seen in the balancing pit between 3000 and 3600 rpm. I he balancing procedure tor flexible rotors is more complicated, because of the elastic deflections of the rotor. Fundamentals of rotor balancing are contained in iso 19499 which gives an introduction to balancing. Balance quality requirements of rigid rotors ird balancing. Pdf practical balancing of flexible rotors for power generation. The aim of balancing any rotor is to achieve satisfactory running when installed on site.
This measurement is not needed for balancing the rotor, but will be used later as a check on calculations. Latham, new york prepared for lewis research center under contract nas318520. A balancing method known as lowspeed holobalancing was developed, which could balance a flexible rotor without test runs at high speeds. Rotor balancing methods may be separated into two categories. Research article a new method for fieldbalancing of high. Friswell college of engineering, swansea university, bay campus, fabian way, crymlyn burrows, swansea sa1 8en, uk. Laser balancing demonstration on a highspeed flexible rotor. Application notes static and dynamic balancing of rigid. The rotor should first be balanced fairly well at low speed. Rotating machinery rotor balancing lifetime reliability. The methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor.
The bearing vibration is usually large and can be rectified by using normal balancing methods. Rotating machinery rotor balancing the aim of rotor balancing is to achieve satisfactory running when installed on site. Rotor balancing methods and instrumentation springerlink. It means no more than an acceptable magnitude of vibration is caused by the unbalance remaining in the rotor. For such cases, low speed balancing can satisfy all balancing requirements. Rotor unbalance is a basic concern in the design and operation of machinery because it is a major cause of excessive vibration. 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 first and second poles each extend radially outwardly from the annular section and form an interpole region therebetween. Shop balancing methods the methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor. May 28, 2017 the methods employed in shop balancing can have a profound impact on the resulting balance condition of the rotor. The procedure utilizes measured runout eccentricities and femodeled rotor mode shapes for the selection of balancing planes. 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.
Investigation of the influence coefficient method for. What is difference between rigid and flexible rotor. Rotordynamics and balancing revisited balancing of. Balancing techniques for highspeed flexible rotors ntrs nasa. 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. That is, flexible rotor balancing procedures take into account rotor flexibility, while rigid rotor balancing procedures do not. 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. Balancing of flexible rotor with bow using transfer matrix. Rotor balancing is a fundamental requirement for the smooth operation of turbomachinery. A balancing method known as lowspeed holo balancing was developed, which could balance a flexible rotor without test runs at high speeds. Contact sulzer for highspeed or atspeed balancing by our experienced technicians and engineers.
The problem is actual for the highspeed rotors working at supercritical speeds rotors of aircraft engines, gas turbine engines of power plants, etc. Every rotor has an individual unbalance distribution along its length, even in series production. Pdf practical balancing of flexible rotors for power. Ny nasa contractor report 2975 balancing techniques for highspeed flexible rotors a. Active balancing of flexible rotors using strain actuators arthur w. These strain actuators would be arranged in a bimorph con. 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. 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. In this context satisfactory running means that not more than an acceptable magnitude of vibration is caused by the unbalance remaining in the rotor. A new method for fieldbalancing of highspeed flexible. 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. A rigid rotor can be balanced by making cor rections in any two arbitrarily selected i rnr u i a. 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. 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 laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The majority of balancing is done on any common, highspeed balancing machine at not higher than 50%. The change in speed affects the centrifugal force, causing bending and twist effects to. The impact of shop balance technique is most important when the rotor is relatively flexible andor long as is common with most turbomachinery.
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. Recent developments toward the establishment of criteria for appropriate levels of residual unbalance in flexible rotors following balancing operations are included. Detailed consideration of errors associated with balancing and verification of residual unbalance are given in iso 19402. Research article a new method for field balancing of highspeed flexible rotors without trial weights y. Balancing is the method to eliminate the imbalance. This document does not cover the balancing of rotors with flexible behaviour. Rotor balancing turbine applied and interdisciplinary. The incremental rotor balancing procedure turbomachinery. An introduction to a unified approach to flexible rotor balancing. 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. Dynamic balancing of rotating machinery experiment technical. Introduction the international standards organization, iso, published standard 19401 balance quality requirements of rigid rotors, which has been. Flexible rotor a flexible rotor might be defined as a rotor which runs above a flexible rotor critical speed. Balancing is a procedure in which the mass distribution of a rotor is checked and, if necessary, adjusted.