Characteristics of the Bending Moment Acting on an Overhung Shaft in a Stirred Vessel

Abstract

Abstract The bending moment acting on an overhung shaft in an impeller stirred vessel was measured using a moment sensor equipped with digital telemetry. The results show that the characteristics of bending moment, such as the mean amplitudes, the amplitude and frequency distributions and the intensity of the amplitude fluctuations are influenced by both the ratio of operational speed to resonant speed (n/nr) and the impeller type. Analysis of the bending moment amplitude shows that the dimensionless shaft bending moment decreases for low values of n/nr and increases with increasing n/nr for higher values of n/nr. The value of the n/nr transition point depends on the type of impeller used in the experiments. Analysis of the power spectral density of bending moment fluctuation shows that the main contributions to the bending moment for low impeller speeds (i.e. well below the first resonant frequency) come from factors related to the fluid flow while the impeller imbalance becomes steadily more dominant as the speed increases.