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BACKGROUND: Understanding the effect of ions on collector generation characteristics is crucial for adjusting the oil/water interface and enhancing mineral flotation. METHODS: We conducted a study of the kerosene droplet generation process in the presence of NaCl, MgCl2, and AlCl3 using a high‐speed motion acquisition system. RESULTS AND CONCLUSIONS: The results showed that the generation process of kerosene droplets could be divided into two stages, droplet expansion and column contraction, according to variations of the droplet width. With the increasing capillary inner diameter, the generation time of the kerosene droplet increased, while the w/h value (column width/column height) of the kerosene column decreased. When the w/h value decreased to 0, the droplet column ruptured, and the droplet separated from the capillary. As the ion valence increased, the equivalent diameter (d) of the kerosene droplet increased due to the ionic hydration and followed the order dAl3+ > dMg2+ > dNa+. Furthermore, as the ion concentration increased, the equivalent diameter increased with the same capillary inner diameter, and the w/h value decreased. A model of the kerosene column height and capillary inner diameter (R) was established to predict the characteristics of the generated kerosene droplet. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Wind barrier is an effective countermeasure to protect vehicles from the lateral wind on sea-crossing bridges. Previous studies focused on the sheltering efficiency of wind barriers and their effects on the aerodynamic/aeroelastic characteristics but ignored the analysis of intrinsic mechanism for dynamic stability, especially for flutter instability, which results only in a vague understanding of the role of wind barriers in flutter. Hence, this study paid attention to the effect mechanism of wind barriers on the flutter characteristics to generate a comprehensive understanding of the coupled relationship between wind barriers and the main structure. Wind tunnel experiments of closed box girders with different aspect ratios were first conducted to unearth the sensitivity of wind-barrier location, wind-barrier shape, wind-barrier porosity, and aspect ratios of main girders to flutter performance. The positive function of wind barriers was discovered, which was contrary to the common view that wind barriers had an adverse effect on streamlined structures. Then, the overall evolution of flutter process affected by wind barriers was investigated in detail from the flutter derivative contribution and modal participation. Simultaneously, local-region responses on the bridge surface to the installation of wind barriers were also studied by a proposed simplified local effect model based on surface fluctuating pressure. Also, the reason for the different influences of wind barriers was revealed according to the analysis from both overall and local levels. Wind barrier is an effective countermeasure to protect vehicles from the lateral wind on sea-crossing bridges. However, a modification of structural aerodynamic shape affected by wind barriers may have an adverse effect on aerodynamic stability, especially flutter instability. This study focuses on the wind-barrier effects on the flutter characteristics of closed box girders with different aspect ratios. The model test shows that there is no obvious positive or negative correspondence between wind barriers and structural flutter performance. If we can make full use of wind barriers, the flutter critical wind velocity can be improved by even 40%. Then, the flutter mechanism of wind barriers is investigated in detail based on the analysis of global derivatives, local derivatives, and unsteady pressure. Finally, the key flutter derivatives and the key function region of the deck surface are obtained, which may provide some references for the application of closed box girders in super long-span bridges. [ABSTRACT FROM AUTHOR]

At present, there is a common problem that the mixing mode is single and it is difficult to overcome the inherent bottleneck of multiphase mixing. A mixing device combining the advantages of jet entrainment and mixing dispersion was designed and built. In an effort to determine the mixing degree of two phases, the mixing coefficient of gas–liquid charging was measured using the cylinder method with the optimal working parameters. To explore the optimization of the mixing conditions and control mechanism of multiphase materials, the law of gas–liquid shear mixing in the process of multi-force field synergistic change was revealed. Based on the testing of the gas injection capacity under different working conditions and the calculation of the gas–liquid two-phase mixing coefficient, it was concluded that the flow rate was the direct key factor affecting the gas injection capacity. The working speed also had a certain impact on the gas injection capacity. When working at a high speed and high flow rate, the jet beam broke through the cutting barrier and presented a superposition effect. The jet impact assisted the rotation, and the suction performance of the device was significantly improved, which was conducive to the mixing of the gas and liquid phases. According to the test results of the measuring cylinder method, the calculated average inflation volume is 0.01 m 3 / (m 2 · m i n) , the inflation uniformity coefficient is 77.51, and the mixing coefficient of the gas and liquid phases is 0.12. [ABSTRACT FROM AUTHOR]

The precise identification of damp, sticky coal gangue; efficient jet nozzle separation; and process layout in a narrow, restricted space are essential technologies for gangue source reduction based on underground gangue photoelectric separation, which is critical for the long-term growth of coal mines. In this paper, the X-ray absorption fine structure (XAFS) method was used to identify the X-ray absorption law of different atoms in coal-based minerals and explore the differences in the microscopic crystal properties of coal gangue; the numerical simulation calculation of four commonly used nozzles—namely, flat, convergent, flat–convergent, and streamline—was carried out using Fluent software for coal gangue jet separation to optimize the nozzle morphology and parameters. The technical characteristics of the underground layout of the photoelectric separation system for coal gangue were expounded, and the technological layout of the separation system was explored. The results showed that the absorption coefficients μ(E) of Al and Si atoms in minerals to X-rays are significantly different, and the XAFS method has the ability to identify coal, gangue, and other minerals. The streamlined nozzle has a long jet core area, slow decay of jet velocity, low gas consumption per unit time, and better performance than the other three types of nozzles. Based on the development and mining system of the Renjiazhuang Coal Mine, three kinds of photoelectric separation system layout schemes of coal gangue were designed, namely centralized layout, distributed layout, and mobile layout. The advantages and disadvantages of each scheme were compared, which enriched the technical means of gangue source reduction. [ABSTRACT FROM AUTHOR]