ZHANG Congcong1, 2, ZHOU Yuzhe3, MEN Rixiu4, FU Xiaorui1, 2, FENG Zemin1, 2, CAI Changwang1, 2
Journal of Vibration and Shock. 2024, 43(20): 183-191.
The circumferential oil-groove on the floating ring bearing has an important effect on the distribution of the outer oil film pressure, which leads obvious nonlinear vibration for the high-speed and light-loaded turbocharger rotor. Based on the fluid lubrication theory and finite element method, a comprehensive model, including the dynamic equation of the TC rotor, the transient form of thermal energy balance of FRBs, the viscosity-temperature equation of the lubricating oil and the thermal deformation equation of FRBs are established, and the corresponding solving strategy is proposed. The accuracy and reliability of the comprehensive model are verified by the experimental results. Taking the turbocharger rotor system for a diesel engine as an example, the transient vibration response in frequency domain of rotor system with different circumferential oil-groove widths and under different inlet oil temperatures is studied by means of three-dimensional vibration waterfall. It shows that the circumferential oil-groove width is increased for 2.4 to 4.8 mm, the rotational speed range of the inner oil film whip/whirl is reduced, and the inner oil film whirl amplitude decreases greatly under different inlet temperatures. However, with the increase of the width of the circumferential oil-groove and the inlet oil temperature, the bearing capacity of the outer film decreases, which leads to a rigid movement of the rotor system, that is, zero-frequency vibration. The amplitude of zero-frequency vibration is higher than that of low-frequency vibration(subsynchronous), which becomes the dominant frequency. when the circumference groove width increases from 2.4 to 4.8mm and the inlet oil temperature is 50°C, the maximum dimensionless vibration amplitude of the rotor system decreases by about 67%, 75% and 83%, respectively. When the inlet oil temperature is 90°C, the maximum dimensionless vibration amplitude of the rotor system decreases by about 38%, 75% and 82%, respectively. When the inlet oil temperature increases to 130°C, the maximum dimensionless vibration amplitude of the rotor system decreases by about 67%, 75% and 79%, respectively. Therefore, for different inlet oil temperatures, the vibration amplitude of the rotor system can be greatly reduced by the circumferential oil-groove, which is conducive to improving the stability of the rotor system. The conclusion can provide theoretical reference for the parameter design of the circumferential oil-groove for the floating ring bearing.