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Technical Papers Authored or Co-authored By Dr.  Robert  H.  Badgley

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Order: #32

32.  Badgley, R. H. , "Advanced Rotor Balancing Techniques: A User's Guide for Factory, Test Cell and Field Applications, " presented at the 5th Turbomachinery Symposium, Texas A&M University, College Station, Texas, October 1976.

SUMMARY: During the past ten years several new methods of performing rotor balancing have corne on the scene. The initial reason for the development of the earliest of these methods, known as ''Modal Balancing", was the need of the steam turbine-generator industry, which produces rotor-bearing systems that are acknowledged to be supercritical. That is, their rotor speeds lie above one or more bending critical speeds eering demand. Precision balancing of truely flexible rotors was the engin-Modal Balancing was the response to this rotor balancing need at a time when neither the existing analytical methods nor the available experimental measure-ment sensors and instruments were sufficiently advanced to perform the job separately. Thus, Modal Balancing combined the then-available techniques for calculating response amplitudes for the various rotor vibrational modes, with then-available instruments for measuring actual installed vibration levels. Particularly difficult was the separation of different modes using the filters-then on the market. Since all vibration data was handled manually, only limited quantities of data could be managed. During the late 1960's and early 1970's, several key advances occurred which made newer balancing methods both desireable and possible. First, other types of rotor-bearing systems began to be designed for supercritical operation. The need for better rotordynamic tools was spotlighted to support these designs, so that today a number of extremely powerful response and stability computer programs are commercially available. These tools can, and are now being used to optimize rotor design from the balancing standpoint...

Order: #33

33.  Smalley, A. J. , Tessarzik, J. M. and Badgley, R. H. , "The Stability of an Asymmetric Rotor in Damped Supports, " ASME Paper No. 78-GT-172, presented at the ASME Gas Turbine Conference, London, England, April 1978.

A general-purpose method of evaluating the stability of an asymmetric flexible rotor, mounted in symmetric damped bearings, is defined. This method evaluates the complex eigenvalues of the rotor system by solving the equations of motion in a rotating coordinate frame. The application of this method to a rotor mounted in tilting-pad bearings is demonstrated. The observed behavior of a number of different rotor configurations is compared with corresponding predictions of stability. For the configurations predicted to be unstable, a distinct and unnegotiable threshold of instability is encountered. The sharpness of this threshold is emphasized by careful balancing at speeds fractionally below the threshold. In a final configuration predicted to be marginally stable, lightly damped resonant behavior, negotiable by balancing, is encountered in the region of the first critical speed.

Order: #34

34.  Badgley, R. H. and Gilbert, J. S. , "Computerized Assessment of Machinery Performance and Health, " presented at the ASME Winter Annual Meeting, San Francisco, CA, December 1978, and published in ASME Symposium Volume BR. H00130, "Diagnosing Machinery Health, " 1978.

ABSTRACT: A number of very important advances have occurred in the last several years in the area of minicomputer hardware and software. Off the shelf computer hardware which can operate in the plant environment now costs no more than the newer analog signal processor instruments, and software now available permits the computer to do virtually automatically all of the data gathering and manipulating steps previously done by hand. Decision-making (diagnosis) software is also now being introduced. As a result, the machinery operator about to update his condition monitoring scheme should investigate the use of the small, on-site computer. This option could very well provide the same data processing power at lower cost than some of the more traditional methods" or for a fixed investment, could provide dramatic improvement in machinery understanding through on-line data analysis and increased flexibility. The low-cost in-plant minicomputer is an engineering tool whose time has come.

Order: #35

35.  Parkinson, A. G. , Darlow, M. S. , Smalley, A. J. and Badgley, R. H. , "An Introduction to a Unified Approach to Flexible Rotor Balancing, " ASME Paper No. 79-GT-161, presented at the ASME Gas Turbine Conference, San Diego, CA, March 1979.

Several successful methods for balancing flexible rotating shafts have been developed In recent years. The methods can apparently be subdivided into a group which is based on modal characteristics and another set which employs influence coefficients. The relative merits of these two approaches have been the subject of much discussion and argument -most of it inconclusive and rather fruitless. The authors consider that, in practice, many of the differences are more apparent than real and that they seem to occur because the various techniques are normally presented in relatively simple and ideal, theoretical terms. This paper represents the start of a Joint project which hopes to resolve the apparent differences and, eventually, develop a unified approach to such balancing. A discussion of the theoretical basis for this unified approach is presented along with a description of a test program conducted to explore the possibilities of such an approach.

Order: #36

36.  Badgley, R. H. , "A Knowledge-Based System Approach to Improved Marine Diesel Engine Condition Assessment, " presented at the Society of Automotive Engineers Government/Industry Meeting & Exposition, Washington, DC, May 1985, and published in Marine Engine Development, SP-625, p. 95-104, Society of Automotive Engineers, Inc. , 400 Commonwealth Drive, Warrendale, PA 15096, May 1985.

Order: #37

37.  Thompson, B. D. and Badgley, R. H. , "Development of an Advanced Hybrid Rotordynamics Model for Vibration Analysis of the Entire Structure of a Marine Gas Turbine Engine, " presented at the Second International Symposium on Transport Phenomena, Dynamics, and Design of Rotating Machinery, and published in Preprints Volume 2: Dynamics, April 1988, p. 212-225.

Order: #38

38.  Thompson, B. D. and Badgley, R. H. , "Application of an Advanced Hybrid Rotordynamics Model to the Complete Structure of a Marine Gas Turbine Engine, " published in Trans. ASME, Journal of Engineering for Gas Turbines and Power, Vol. 110, October 1988, p. 578-584.

Order: #39

39.  Thompson, B. D. , Badgley, R. H. and Raczkowski, R. , "Methods and Procedures for Trim Balancing the LM2500 Marine Gas Turbine in the Test Cell and Aboard Ship, " ASME Paper No. 89-GT-318, presented at the ASME Gas Turbine and Aeroengine Congress and Exposition, Toronto, Canada, June 1989.

ABSTRACT: Extensive fleet experience with LM2500 marine gas turbines shows that engines with higher than normal vibration are more likely to show early wear. Gas generator rotor unbalance has been identified as the main cause of high vibration. Rotor rebalancing reduces vibration to acceptable levels, at the same time reducing or eliminating many wear out modes. Initially, the only rebalance option was to remove the gas generator from the ship and send it to the depot. The high cost of this option led to a search for alternatives, and the successful development of a procedure for rebalancing the gas generator rotor aboard ship. The method adopted was the well known influence coefficient procedure, developed by the National Aeronautics and Space Administration (NASA) in the late 1960's. This method is well suited for implementation on portable computers, and fits readily into a practical procedure for use by trained technicians. The NASA program originally included a procedure to minimize peak residual vibration. Navy engineers added an improved optimizing procedure and a method to account for engine nonlinearities. Rebalancing involves mounting four external accelerometers on the engine, along with a tachometer to give a one-per-rev signal for phase angle measurement. Baseline vibration measurements, together with stored influence coefficients for the LM2500 engine series, permit first shot multi-plane, multi-speed trim correction weights to be calculated. The compressor case is readily opened and the weights installed without disturbing the engine. Application of this procedure has been highly successful: vibration levels of less than 0. 001 inch peak-to-peak over the entire speed range have been achieved. The avoided cost of removal, replacement and repair of an LM2500 is estimated to be about $500, 000.

Order: #40

40.  Badgley, R. H. and Shade, W. A. , "Vibration Analysis for Immediate Assessment of Battle Damaged Gas Turbine Engines, " ASME Paper No. 89-GT-96, presented at the ASME Gas Turbine and Aeroengine Congress and Exposition, Toronto, Canada, June 1989.

ABSTRACT Extensive fleet operational experience now exists for the LM2500 marine gas turbine engine. Based upon this experience, this engine is susceptible to a number of wear-out modes caused by excessive operational stresses. It has been found that the principal factors responsible are engine power profile, aero-dynamic disturbances and self-generated vibration.The failures involve both external and internal engine components.External components which fail can readily be replaced or repaired. Rapid replacement or repair has had a positive impact on engine availability. For failed internal engine components, however, depot repair was originally planned. High repair costs and operational impact from depletion of rotable pool spares accelerated the need for in-place repairs. A number of such repairs have been developed and validated, resulting in substantial cost savings and increased engine availability. Special repairs have also been developed to reduce the operational stresses themselves.

Order: #41

41.  Thompson, B. D. , Badgley, R. H. and Hartranft, J. J. , "Experience from Expansion of On-Board Maintenance for Marine Gas Turbines, " ASME Paper No. 89-GT-232, presented at the ASME Gas Turbine and Aeroengine Congress and Exposition, Toronto, Canada, June 1989.

Order: #42

42.  Badgley, R. H. , "A Knowledge-Based Approach to Plant Machinery Condition Based Maintenance, " presented at the First International Conference on Improving Reliability in Petroleum Refineries and Chemical and Natural Gas Plants, Houston, Texas, November 1992.

Machinery system availability strongly affects overall plant availability in the petroleum, chemical, and natural gas industries. Unscheduled or unnecessarily scheduled maintenance actions can result in large lost-production costs. Once failure has occurred, machinery repair costs also can quickly become excessive. However, there are few if any machinery systems in service today or being purchased that cannot be made cost-effectively free of operating failures. This objective may be achieved through the use of new Condition Based Maintenance techniques which are based upon application of an expert system with a comprehensive knowledge base.These tools can diagnose simultaneously all failure modes which can be described in engineering terms.

The ratio of benefits to cost savings achievable by this method is conservatively estimated to be at least six-to-one, and in one case has exceeded more than 100-to-1. Experience now shows that machines with low levels of vibration at all frequencies of interest usually have adequate mechanical integrity -that is they experience little or no mechanical degradation during operation.This is important because vibration is not only a symptom, but is also the root cause of many, if not most,mechanical failures. After excessive mechanical vibrations have been identified and eliminated by a Multi-Frequency Analysis, most failure modes no longer occur. After satisfactory mechanical integrity has been established, then Condition Based Maintenance monitoring can be used to provide early warning of distress in specific internal components. Inplace repairs then are possible, and often are most cost effective, because they allow the machine to be returned to service at the earliest time. New or revised maintenance procedures often result from the improved knowledge of machinery systems condition, further improving the picture.

Order: #43

43.  Badgley, R. H. , "A Knowledge-Base Approach to Safe, High Quality Aircraft Engines and Helicopter Gearboxes, " published in the Institution of Engineers Singapore (IES) Journal, Vol. 35, No. 2, March 1995, p. 54-59, Institution of Engineers, Singapore.

ABSTRACT Engine and gearbox quality, as measured by vibration and other key parameters, strongly affects flight safety and cost of ownership. Unscheduled or unnecessarily scheduled maintenance actions can result in large financial losses due to lack of service availability for commercial aircraft engines, and excessive maintenance-caused downtime for military aircraft. Once failure has occurred, repair costs also can quickly become high because increasing numbers of internal parts are damaged as the failure progresses.

With today's technology, however, there are few if any engines and gearboxes now in service or being purchased that cannot be made virtually free of operating failures in a cost-effective manner. The key is the use of new Condition Based Maintenance techniques, based upon application of an expert system with a comprehensive knowledge base. With such a tool, technicians can diagnose precisely the presence of almost all failure mode precursors.The ratio of benefits to cost savings achievable through this approach is conservatively estimated to be at least six-to-one,and in one case has exceeded 100-to-1. Experience now shows that machines with low levels of vibration at all frequencies of interest usually have adequate mechanical integrity - that is they experience little or no mechanical degradation during operation. This is important because vibration is not only a symptom, but is also the root cause of many, if not most, mechanical failures.

After excessive mechanical vibrations have been identified by a Multi-Frequency Analysis, and eliminated through good engineering practice, most failure modes will no longer occur. After satisfactory mechanical integrity has thus been established, then Condition Based Maintenance monitoring can be used to provide early warning of distress in machinery internal components. In place repairs, where possible, may be most cost effective, because they allow the equipment to be returned to service at the earliest time. New or revised maintenance procedures may also evolve from the improved knowledge of machinery condition, further improving the picture.

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