Abstract The present work presents the experimental analyses of a rigid (short) and a flexible (long) rotor subject to thermal unbalance effects. The rotors are supported by a ball bearing and by a cylindrical journal bearing. The differential heating generated in the journal bearing is responsible for the thermal unbalance. The results obtained with the short rotor at 7 krpm showed an increase in the synchronous amplitudes but slight phase changes before stabilization. The pronounced hysteresis of the synchronous amplitudes obtained during coast-down proved that the amplitude increase is due to the thermal unbalance. The results obtained for the long rotor at 6.6 krpm showed the same stabilized response when start-up was performed in 180 s. However, an instability leading to journal bearing contact was triggered when the start-up time was decreased to 80 s. The presented experimental results are the synchronous amplitudes and phases, the mean temperatures, and the maximum temperature differences of the journal and of the bearing and the phase lags between the high spot and the hot spot.

中文翻译：

---

刚性和柔性转子中轴颈轴承引起的热不平衡效应：实验分析

摘要 目前的工作介绍了受热不平衡影响的刚性（短）和柔性（长）转子的实验分析。转子由滚珠轴承和圆柱形轴颈轴承支撑。轴颈轴承中产生的不同热量是造成热不平衡的原因。用 7 krpm 的短转子获得的结果显示同步幅度增加，但在稳定之前有轻微的相位变化。滑行期间获得的同步幅度的明显滞后证明幅度增加是由于热不平衡造成的。长转子在 6.6 krpm 下获得的结果表明，在 180 秒内启动时，具有相同的稳定响应。然而，当启动时间减少到 80 秒时，会触发导致轴颈轴承接触的不稳定性。给出的实验结果是同步幅度和相位、平均温度、轴颈和轴承的最大温差以及高点和热点之间的相位滞后。