Vibrations in Turbo Machinery

Paper No. 49

F. R. Szenasi, Use of Vibration Measurements in Structural Evaluation, ST Div/ASCE, Atlantic City Convention, April 29, 1987 .

When a structural natural frequency coincides with an operating speed, high vibrations of machinery, structures and foundations can occur and cause machinery of structural damage. This paper presents field measurement techniques to evaluate the effect of structural responses on machinery that can be employed prior to machine startup. Vibration measurement techniques are presented to aid in diagnosing structural problems. The use of a mechanical shaker and modal analysis in evaluating the structural response of several field structures is presented along with the solutions to correct the vibration problems. Vibration measurements (before and after modifications) are presented to show the changes in natural frequency and reduction of vibrational response. In one case, a mechanical shaker was used to define structural response and sensitivity of a structure to unbalanced machinery. Another case describes the successful modification of the foundation of a 10,000 HP axial fan.

 

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