Diagnosis and prognosis of oil whirl in journal bearing using acoustical measurement

Abstract

Clearance and length-to-diameter (L/D) ratio are essential parameters for the optimum journal-bearing design. This article investigates the effect of load and rotational speed of the shaft on those two parameters. Under specific operating conditions, oil whirl is a prevalent rotor dynamic instability that can result in significant machine faults if left unattended. Experiments are carried out at different speed and loading conditions while varying the clearance (0.05 mm and 0.15 mm) and L/D ratio (1.5 and 2) of journal bearings. The data analysis used statistical features, like skewness, kurtosis, and spectral kurtosis, to evaluate the severity of the oil whirl and the system's behavior. Comparative analysis was carried out using these statistical measures to identify the best feature for analyzing oil whirl. The results indicate that the onset and intensity of the oil whirl are strongly influenced by both clearance and L/D ratio, and considerable negative skewness, high kurtosis, and high spectral kurtosis values are seen under different load and speed combinations. This study emphasizes the importance of optimizing both clearance and L/D ratio in bearing design to mitigate oil whirl under various operating conditions.