Investigation of Shaft Instability which is Supported by Hydrodynamic Journal Bearing

• Main Author: Muttaqin Ishak, Jusacc
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/40585
• Institution: Institut Teknologi Bandung

For industrial machines with heavy load and high rotational speed, hydrodynamic journal bearings usually use to support the machine rotor. During operation, hydrodynamic journal bearings sometimes encounter instability. In order to study this phenomena, some researches have been done. Unfortunately, the results can’t reveal the type and cause of the instability. So, this research is subjected to investigate the type and cause of shaft instability which is supported by hydrodynamic journal bearing. In this research, two tests have been done. The first one is journal bearing test under ISO VG32 lubrication and the second one is journal bearing test under ISO VG46 lubrication. In every test, there are two measurements of shaft vibration. The first one is shaft vibration measurement of increased rotational speed and the second one is shaft vibration measurement at constant rotational speed. The purpose of shaft vibration measurement of increased rotational speed is to determine vibration response change due to speed increment. This measurement results are vibration signals, RMS vibration value, gap between shaft and displacement sensors, and average shaft centerline. Meanwhile, the purpose of vibration shaft measurement at constant rotational speed is to determine the instability phenomena occurred on shaft. This measurement resulted time domain vibration response, frequency spectrum of vibration, and uncompensated orbit. Based on the results, it is known that kind of instability occured on shaft is oil whirl. Frequency of oil whirl that occurred is 0,5×RPM. For shaft that tested use ISO VG32 lubricant, ?TH inboard is 2.830 RPM and ?TH outboard is 2.930 RPM. Meanwhile, for shaft that tested use ISO VG46 lubricant, ?TH inboard is 3.040 RPM.