Torsional Vibration of Turbomachinery
Including application case studies and in-depth interpretation of computer-generated results, this book offers practical answers to preventing excessive damage, failure and noise due to vibrations in machines.
TABLE OF CONTENTS Torsional Vibration of Turbomachinery
9.3.2: Case study: Effect of applied torque phase angle changes
9.3.2 Case study: Effect of applied torque phase angle changes
For the same vibration model as in Case Study 9.3.1 and with the same modal damping values ( ?=0.01), examine the effect of varying the applied torque phase angles on the steady-state torque response in span 1-2 under the following conditions. Torques are to be applied only at nodes 1 and 3 and the phase angle of the torque applied at node 3 relative to node 1 is to be varied in 45 increments from 45 to 360 . Evaluate how the response torque varies in span 1-2 for
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The excitation frequency being at the natural frequency of mode 2 (3.1295 Hz).
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The excitation frequency being at the natural frequency of mode 3 (5.419 Hz).
Note that mode 1 is the rigid-body mode at zero frequency.
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What would be the phase angle difference at nodes 1 and 3 to achieve maximum and minimum vibration response in each case?
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What do you use to determine this most easily?
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Why are the response versus phase angle difference plots not quite symmetric about 180 ?
Solution to Case Study 9.3.2
1. The first step is to examine the mode shapes for the system as shown in Fig. 7.1. As the applied torque frequency is to be set first at the mode 2 natural frequency and the damping is light, the vibration response will be mainly in mode 2. For mode 2 it is seen at nodes 1 and 3,...
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