Improved analysis method for rotor stability

In the rotary machine field, the lack of accuracy in the analysis for rotor stability is unacceptable and must be improved. This lack of accuracy is mainly caused by discrepancies between the calculated and measured oil film coefficients. Therefore, the conventional analysis method, in which the Reynolds equation is solved by treating the rotor vibration as a slight whirl and by employing the fixed boundary condition for oil film formation, is flawed. The authors, therefore, re-evaluate the boundary condition for oil film formation, and propose a new analysis method of oil film analysis by considering the real shaft vibration amplitudes. They also compare the oil film coefficients by the proposed method with that by the conventional method.