Study Of Macro-Instabilities Behavior In A Stirred Tank

Mixing processes are common unit operations in chemical engineering. The knowledge of fluid flow is important to acquire the mixing characteristics. The studies of fluid flow adopted more and more frequently both in experiments and numerical simulations. In fact, the flow in stirred tank is unstable, and the fluxion changed from time to time, as well as space. Macro-instabilities(MI) are the most apparent. The experimental methods for macro-instabilities studies, as well as the analytical methods for experimental data have crucial influence to the results.In this paper, the digital-signal processing approaches for macro-instabilities were analyzed and the combined approach of power spectral density and wavelet analysis was proved to be suitable for analyzing one-dimensional low-frequency signal with noise and peak value. Experiments were carried out in a flat-bottom cylindrical stirred tank with 0.476m in diameter. A standard Rushton turbine was used in the experiments. The torque of the impeller was measured by torque transducer and analyzed by using the combined approach. Results show that there are...