Note that increasing of air volume rate strongly influences on the size and distributions of bubbles. The corresponding camera shots of considered cases are presented in Figure 2. Other parts of experimental stand: AP, air pump AV, automatic valve to maintain a constant air pressure in the tank and AM, air flow metres WM, water flow metres WP, water pump. Video frames are collected by the camera. Two laser-phototransistor sensors (L1, L2) measure the perturbations of the system. Pressure is measured by two sensors (P1, P2).
Physiotools momentum generator#
Water fraction is circulated in the blue loop, whereas air is provided to the bubble generator (BG) by a side branch (yellow). Finally, the pressure difference between the inlet and outlet of the minichannel was measured using the silicon pressure sensor MPX12DP.įlows analysed in the work were configured with a vertical mini pipe of diameter 5 mm (see Fig. Data from the sensors was acquired by the acquisition system (Data translation 9804, an accuracy of 1 mV for voltages in the range −10 to 10 V) at a sampling rate of 1 kHz. Bubbles inside the minichannel bend the light, which modifies the light intensity on the silicon sensor. The sensor consisted of a laser (which generated the laser beam with a diameter of 3 mm), the lens and silicon sensor (which were placed in focal point of lens). The content of the minichannel (bubbles or liquid) has been qualitatively assessed using the laserphototransistor sensor. 2 Experimental Setup and Measurement Resultsįlow patterns were recorded with using the Casio EX-F1 digital camera at 1200 fps (336×96 pixels). In this article, we continue previous report and apply the multifractal approach to study crossover from bubbles to slugs patterns. suggested multiscale morphological analysis of conductance signals. , using the recurrence features studied two-phase flow bifurcation due to turbulence, self-aggregation phenomenon, and stable flow conditions in a two-phase flow through a mini-channel using the laser transitivity data. Stabilities of flows were also investigated by the largest Lyapunov exponent and correlation dimension. determining the borders between flow patterns. The flow patterns in a vertical minichannel were studied by Faszczewski et al. The nonlinear analysis of the flow of oil–water also carried out showing that such analysis is useful for identification of the flow patterns in inclined channel with larger diameters. Novel measurement techniques and nonlinear results analysis led to the identification of flow patterns of the oil-gas-water mixture from mini-conductance probe array and vertical multielectrode array conductance sensor.
![physiotools momentum physiotools momentum](https://vcj0u6u8x2-flywheel.netdna-ssl.com/wp-content/uploads/2019/05/Screenshot_2019-01-21-13-33-57-576x1024.png)
The correlation dimension and Kolmogorov entropy were used by Jin et al. , used selected nonlinear techniques including the Hurst and Lyapunov exponents, correlation dimension, and pseudo-phase-plane trajectory to analyse the pressure fluctuations of two-phase flow. To increase the ability to identification and interpretation, Wang et al.
![physiotools momentum physiotools momentum](https://slidetodoc.com/presentation_image/3e3c4ead594dc46fb8d4fc93982d1420/image-113.jpg)
Such analyses have been carried out recently by many scientists. The alternative way of flow pattern identification is based on the analysis of dynamics of two-phase flow. In addition, the visual observations of gas and liquid arrangement inside the minichannel are used for flow pattern identifications. Usually, the two-phase flow patterns are identified by calculation of the average values of such parameters as mass or volume flux of phases, void fraction, phase momentum flux, dimensionless flow rate, superficial velocity, and others. Such applications demand understanding and identification of flow dynamics and two-phase structures. Gas-liquid two-phase flows play important role in production processes such as petroleum industry, chemical engineering, nuclear and thermal engineering, and proposed innovative techniques of thermal energy harvesting in two-phase oscillating structures of heat pipes.