The Influence of a Skewed Disk on a Flexible Rotating Shaft

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Virginia Tech

This thesis describes the experimental test results and computer simulation investigations which were conducted to verify the existing theory of skewed disk forced response predictions. The experimental tests were conducted on a horizontal flexible shaft rotor system supported in two hydrodynamic journal bearings. The computer simulations were conducted with a program that uses a matrix transfer method to get the desired solution. The agreement between experiment and simulation is very good for most skewed disk response characteristics. The influence of measurement errors and operation condition uncertainties are discussed.In the first part of this study, the dynamic behavior of experimental investigations focused on two different skewed disk designs which were mounted at midspan, 1/3 span and 2/3 span of the shaft. The two skewed disks were designed to allow a fine angle adjustment of the desired skew angle. The two designs are (a) the angle tiltable disk and (b) the couple unbalanced mass disk. The experimental results are shown to be close to the theoretical predictions of other authors.In the second part of this study, an existing computer program was used to simulate the experimental test rotor. The results give excellent qualitative agreement although there are some differences in quantitative analysis comparisons. The forced response characteristics of the computer simulation match the experimental results. It has been shown that by using the approximate linear skewed disk model, it is possible to get similar results to the experimental tests for similar disk skew conditions.

skew, skewed disk, flexible shaft, dynamic rotor