Morton Effect Calculation and Analysis of Shop Test Results for Single-Shaft Multistage Centrifugal Compressors

Abstract

In the manufacturing process of single-shaft multistage centrifugal compressors for process gases, factory tests are conducted to confirm that the lateral vibration satisfies the allowable limits. One of the problems that must be taken care of during the test is the increase in vibration due to the Morton Effect. The Morton Effect is a thermal bending vibration caused by the non-uniformity of the oil film temperature of the bearing, and many troubles have been reported in overhung rotors. However, there are few reports of the Morton Effect in single-shaft multistage compressors. This is thought to be because even if the Morton Effect did occur, it was often only a minor problem. Although it is a minor problem, it is necessary to predict and evaluate the Morton Effect in order to prevent a prolonged test process and costly countermeasures. In this study, a calculation method for the Morton Effect has been developed for a single-shaft multistage centrifugal compressor, and an evaluation index for the Morton Effect is proposed. The developed method is verified and the validity of the proposed evaluation index of the Morton Effect is checked using cases of increased vibration that occurred in factory tests.