TORSIONAL VIBRATION OF ROTARY
AND RECIPROCATING MACHINES
FULL-DAY MINI-COURSE
This is a description of a mini-course that our president and chief engineer, Mark A. Corbo, P.E., teaches at the client’s site. Depending on the amount of audience interaction that takes place, the mini-course lasts for about 7 to 8 hours. The mini-course is split into two halves of approximately equal length. The first half consists of a general primer on the fundamentals of torsional vibration and a generic design procedure that can be used for all rotating equipment. The second half focuses exclusively on reciprocating machines and the specific manner in which they should be handled from a torsional analysis standpoint.
An approximate agenda for the mini-course is as follows:
- Introduction
- Torsional Vibration of Rotating Machinery
- General Description of Free and Forced Torsional Vibration
- Preparation of Lumped Parameter Models
- Undamped Torsional Vibration Analysis
- Methods for Checking Computer Results by Hand
- Generation of Campbell Diagrams
- Torsional Vibration Excitation Sources
- Synchronous Motor Startups
- Variable Frequency Drives
- Determination of Interference Points
- Elimination of Interference Points by Inspection
- Representative Excitation Torque Magnitudes
- Common Damping Sources
- Determination of Damping Coefficients
- Steady-State Damped Torsional Vibration Response Analysis
- Transient Torsional Vibration Analysis
- Determination of System Adequacy
- Shaft Endurance Limit Determination
- Shaft Fatigue Life Analysis
- Methods for Eliminating Problems
- Overall Analysis Procedure
- Torsional Vibration of Reciprocating Equipment
- Modeling of Crankshafts
- Modeling of Connecting Rods and Reciprocating Parts
- Gas Pressure Excitations
- Inertia Excitations
- Fourier Coefficients
- Major and Minor Orders
- Factors that Introduce Inaccuracy into Reciprocating Analyses
- Accounting for Uncertainties in Analysis
- Forced, Damped Response Analysis of Reciprocating Equipment
- Effect of Changing Reciprocating Compressor Load Steps
- Effect of Changing Engine Loading Conditions
- Engine Misfire Condition
- Reciprocating Equipment Criteria for Acceptability
- Methods for Eliminating Problems
- Viscous Dampers
- Elastomer-in-Compression Couplings
- Overall Analysis Procedure
- Sample Problem
- Reciprocating Compressor Empirical Observations
- Good Reciprocating Compressor Design Practices
- Conclusion
Some of the benefits a client’s personnel receive from taking this mini-course include the following:
1. A greater familiarity with torsional vibration fundamentals which would allow them to communicate more effectively with experts in the field.
2. A better understanding of the meaning and validity of torsional vibration results obtained from consultants and/or in-house computer codes.
3. A better understanding of the torsional vibration causes of common
problems which would assist them when trying to troubleshoot field and test-stand problems.
4. A better feel for which components play an important role in torsional vibration behavior and which ones have little impact. This would be valuable when evaluating potential design changes.
5. An appreciation that torsional vibration analysis can be performed in a practical and timely manner and does not require a "research project."
6. An appreciation for the large role that torsional vibration behavior plays in the reliability of reciprocating equipment and for the importance of evaluating that behavior in the design stage.
The mini-course is presented using multi-color PowerPoint presentation software. Each employee the client sends to the mini-course receives a complimentary copy of our paper, "Practical Design Against Torsional Vibration." Additionally, Mr. Corbo will bring along a pdf file containing all of the slides used in the mini-course. The client is free to make individual copies for as many course attendees as desired.
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