The bending moment acting on the overhung shaft of a gas-sparged vessel stirred by a Rushton turbine

as one of the results of fluid and structure interactions in stirred vessels

was measured using a moment sensor equipped with digital telemetry. An analysis of the shaft bending momentamplitude shows that the amplitude distribution of the bending moment

which indicates the elasticity nature of shaftmaterial against bending deformation

follows the Weibull distribution. The trends of amplitude mean

standard deviation and peak deviation characteristics manifest an “S” shape versus gas flow. The “S” trend of the relative mean bending moment over gas flow rate

depending on the flow regime in gas-liquid stirred vessels

resulted from the competition among the nonuniformity of bubbly flow around the impeller

the formation of gas cavities behind the blades

and the gas direct impact on the impellerwhen gas is introduced. A further analysis of the bendingmoment power spectral density shows that the rather low frequency and speed frequency are evident. The low-frequency contribution to bending moment fluctuation peaks in the complete dispersion regime.