Experimental Study on Characteristics of Pressure Fluctuating Signals in the Novel Circulating Jet Mixer

Experimental study on characteristics of pressure fluctuating signals in the novel circulating jet mixer

Huibo Meng, Yanfang Yu, Jianhua Wu

Key Laboratory of Liaoning Province for Efficient Chemical Mixing Technology, School of Energy and Power Engineering, Shenyang University of Chemical Technology

Abstract:

A novel Circulating Jet Mixer (CJM) has been put forward as a novel type unites operation for mixing. By compassion with conventional stirrers, the novel CJM had effectively improved the flow structures in the tank reactor and exhibited outstanding performance in chemical process intensification field. The flow characteristics in the novel CJR had not been reported by now.

Pressure fluctuation time series signals at different conditions were measured by the high precision data-acquisition system. The spatial distributions of pressure fluctuation amplitudes varied with different position and increased with the increase of Re. The power spectrums distributions in frequency domain were analyzed and the values of inherent frequencies were lower than 5 Hz. The power-law attenuation relationship between power spectral density amplitude and frequency was discovered. The probability distribution functions of the pressure fluctuations were obtained and compared with the corresponding normal distributions by ¦Ö2 hypothesis test. The deviation from the normal distribution was quantitatively analyzed based on skewness and flatness. The Hilbert-Huang Transform was used to process time-frequency and energy characteristic of the instantaneous pressure time series in the novel CJM.

Intrinsic Mode Entropy was also firstly introduced to reveal the sequence complexity of the pressure fluctuation time series in the novel CJR. The regularities of sample entropy and the intrinsic mode entropy were revealed at different parameters. The scaling law of extended self-similarity for the nth-order structure function of the pressure increment had been analyzed in the temporal-spatial scales.

The nonlinear dynamics characteristics of flow field in CJR were investigated by using a new chaotic attractor morphological analysis method based on Takes Theory. Both attractor moment and the perimeter measure analysis of attractor area were employed to evaluate the morphological evolution of the attractor in its unfolding process. The recurrence plot and recurrence quantification analysis was introduced to reveal the recursion phenomenon in the novel CJM.