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The efficiency of the pump device is an important parameter to judge the overall dynamic performance of the pumping station. The commonly used method at home and abroad is to carry out model tests of the pump device. The performance parameters of the prototype pump and pump device are obtained by the similarity conversion formula. However, at present, there are not many device model tests for large vertical submersible pumps. Taking a large vertical submersible mixed-flow pumping station in China as an example, research predicted the performance of the pump device through a model test and a submersible pump prototype test. The results show that the model test of the large vertical submersible mixed-flow pump device has a maximum efficiency of approximately 77.8%, and the prototype test conversion device has a maximum efficiency of approximately 80.33%. The device model test and the pump factory prototype test results are compared. It is found that the performance parameters of the pump measured by the prototype test are in good agreement with the device model test under the design conditions, and there is a certain error when the deviation from the design conditions is significant. The device model test and the factory test of the pump are indispensable in the large-scale road of submersible pumps, and a large number of tests are needed to sum up the experience.

Fat, oil, and grease (FOG) floating particles in the sump of sewage pumping stations will accumulate together to form rigid layers, resulting in failure for pump device. To overcome this, the free surface vortex (FSV) technique has been considered and applied to transport floating particles toward the submerged suction pump inlet. This paper investigates the potential of vortices as a means of downward motion of FOG. The entrainment capacity of FSV is investigated by numerical simulations using a coupled level-set and volume-of-fluid method. Two coherent structures are decomposed by proper orthogonal decomposition: FSV represented by the first two orders with high energy content and spiral vortex bands represented by low energy and high order models. The extracted ridges of the finite-time Lyapunov exponent (FTLE) delineate different regions of the flow field and effectively capture the evolution of Lagrangian coherent structures. The floating particles in the sump are first caught by the dividing line formed by the FTLE ridges, mixed in the entrainment zone, and then merged into the vortex. The enstrophy production term dominates the development of vorticity. Subject to the influence of flow velocity gradients, both radial and tangential vortices undergo a transition into axial vortices. This transformation enhances the vortex's capacity to entrain particles within the vortex core area, leading to their rapid inward spiraling toward the vortex center and eventual expulsion due to the vortex's entrainment effect. [ABSTRACT FROM AUTHOR]

The impact of drop trains is widespread in industrial and agricultural applications, as well as in nature, making it crucial to investigate. In this study, the impact of drop trains on solid surfaces is experimentally investigated using a high-speed camera. A catastrophe phenomenon that had previously been overlooked is discovered: with the successive impact of drop trains, the impact result undergoes a discontinuous catastrophe, from a thin film impact generating the crown splash to a thick film impact generating the Worthington jet. The thickness of the thin film is less than 0.23 times the impact drop's diameter, while the thickness of the thick film ranges from 0.52 to 1.05 times the impact drop's diameter. The reason for the catastrophe is revealed from a phenomenological perspective. The number of impact drops and the impact Weber number are important factors determining the occurrence of catastrophe, and the critical number of impact drops for the catastrophe is linearly and positively correlated with the impact Weber number. Based on the cusp catastrophe theory, a catastrophe threshold model for drop train impact is established. This model is able to predict the threshold for the occurrence of catastrophe and provide a method for identifying the thin film stage, the thick film stage, and the transient catastrophe stage between these two stages. The catastrophe threshold model achieves the identification accuracy of 83.48%, 91.72%, and 77.50% for the total measured data, the thin film stage, and the thick film stage, respectively, indicating its good performance. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue on hydraulic structure safety monitoring. It includes several contributions that propose novel methods and technologies in the field. The contributions cover a range of topics, including the analysis of dam structural characteristics using the finite element method, the application of artificial intelligence algorithms in hydraulic structure analysis, the use of machine learning and statistical methods in streamflow forecasting, and the use of UAV technology to analyze the morphology of drifting ice on water surfaces. The document concludes with recommendations for future research in the field. [Extracted from the article]

This document emphasizes the significance of pumping stations in water conservancy engineering construction, particularly in flood control, irrigation, and water supply. The construction and management of pumping stations face challenges due to outdated technology and equipment, impacting their efficiency and increasing operational risks. The special issue focuses on advancements in pumping station system research, including upgrading strategies, studying efficacy and stability, and exploring energy conversion technologies. The published articles cover various topics related to flow distribution, water-filling processes, internal flow characteristics, and flow-induced noise. The research contributes to enhancing the performance, efficiency, and stability of pumping stations, ultimately ensuring water supply security and sustainable development. [Extracted from the article]

Freeze–thaw-cycle damage is one of the main aging problems of concrete engineering in cold regions, and the analysis of its damage mechanism has become a focus in the field of concrete aging. In this paper, on the basis of the rapid indoor freeze–thaw tests designed and carried out on concrete, computed tomography (CT) tests were carried out on concrete samples with different numbers of freeze–thaw cycles. Using CT image recognition and three-dimensional reconstruction technology, the pores, aggregates, cement matrix, and other components within the material were extracted during the freeze–thaw process. A detailed analysis for the size distribution of pores on a microscopic scale was conducted. The damage evolution law of the interfacial transition zone under the freeze–thaw action was analyzed, providing strong support for checking the validity of rapid freeze–thaw test results. [ABSTRACT FROM AUTHOR]

Psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are two distinct inflammatory joint diseases that can coexist in some patients. This case report discusses the treatment of a 71-year-old woman with PsA and RA using a combination of immunoadsorption therapy and antirheumatic drugs. The patient experienced relief from joint discomfort and a reduction in skin rash after multiple treatment cycles. The article emphasizes the importance of tailored treatment for PsA and the potential effectiveness of immunoadsorption therapy in managing severe psoriasis. However, further research is needed to fully understand the long-term safety and impact of certain medications in treating PsA. [Extracted from the article]

To address the significant energy waste generated by axial flow pumps, this paper proposes an intelligent optimization method based on physics-considering machine learning. First, a highly parameterized geometric design theory is constructed using six featured variables to achieve a complete three-dimensional modeling of the blade geometry. Four hundred preliminary cases are studied using the computational fluid dynamics method with various combinations of these featured variables to obtain a preliminary solution. The best preliminary design has an efficiency of 83.33%, and a head of 5.495 m. To further improve this performance, this paper also presents a high-precision prediction model for the energy performance of axial flow pump based on back-propagation neural network and the encoding layers of random sampling and local feature aggregator network created. Afterwards, a multi-population genetic algorithm is used to quickly find the optimal solution within the prediction mode range. The algorithm achieved a highest efficiency of 86.373% and was validated by numerical simulation with a value of 86.057% and a prediction error of 0.316%. Compared with the preliminary solution, the efficiency of the optimized axial flow pump is increased by 1.615%, with a wider high-efficiency range and an optimal operating point closer to the design conditions. Overall, this intelligent optimization method has the potential to significantly reduce the design time of axial pumps and increase their performance. [ABSTRACT FROM AUTHOR]