Michiyuki Takagi

Diagnosis of Rotor Vibration using Wavelet Analysis when Lubricant in Bearings is Reduced

We developed a diagnosis method for an abnormal rotor vibration with reducing lubricant in tilting pad journal bearings. We suggest a method of diagnosis based on a statistical approach using repetition in an incidental vibration signal. That repetition is calculated using normalized amplitude of vibration for each frequency to diagnose anomalies early. The time-frequency characteristics of vibration amplitude were calculated using continuous wavelet analysis. On this diagnosis method, we compared measured repetitions with pre-measured repetitions of abnormal vibrations using inner products. We applied the diagnosis method to the measured vibration. We found that incidental low-frequency vibration occurred by reducing the lubricant, and the low-frequency vibration became a steady high-frequency vibration as the lubricant decreased. The diagnosis method detected the occurrence and the transition of the rotor vibration when lubricant in the bearings was reduced.

Double Disk Rotor Model Analysis of Dynamical Property of Damper Bearing.

The double disk rotor model is used to analyse the second bending vibration mode generated by unbalance in a damper bearing-supported process compressor. First, a Q-factor map of the model is discussed. It has been shown that this type of map is a highly useful tool in selecting the most suitable parameter sets for rotor design. Secondly, a Q-factor map numerically generated by FEM is used to evaluate the model. The shapes of the Q-factor maps are classified according to vibration mode type. From this classification, the features of each vibration mode are extracted and the cause of the vibration can be analysed. The double disk rotor model is also used to decide on parameters for FEM calculation. The results suggest that the model provides a powerful tool for the simple creation of Q-factor maps.

Study of rotational bending stress in multi-stage centrifugal pump shafting.

多段遠心ポンプ軸系を模擬した装置により, 環状シールの偏心や傾きのミスアラインメントが軸の回転曲げ応力に及ぼす影響を実験的に検討し, 計算結果と比較した. その結果, 下記の事項が明らかになった. バランスブッシュが軸に対して下方に偏心していたり, 軸のたわみ角と逆方向に傾いていると回転曲げ応力が大きくなる. ブッシュのラビリンス状のみぞを大きくすると回転曲げ応力が減少する. 計算値は実験値とほぼよく一致する.