As the core power equipment of the deep-sea mining system, the deep-sea mineral lifting pump continuously operates under harsh service conditions coupled with high hydrostatic pressure, complex marine environments, and solid particle media. Its operating state shows obvious strong nonlinearity, time-varying fluctuation, and local abrupt change features. Therefore, time series health state prediction of the deep-sea mineral lifting pump is of vital engineering significance for realizing predictive maintenance and ensuring the safety of offshore trials and mining operations. Taking the 500 m-level offshore sea trial conducted in the Xisha area of the South China Sea as the engineering background, four critical health characteristic parameters, including shaft power, pump efficiency, motor winding temperature, and outlet radial vibration, are selected to construct a hybrid CNN-LSTM time series prediction model. Comprehensive model evaluation metrics and ablation comparison experiments are adopted to analyze the multi-step-ahead prediction performance of the proposed model. The results show that the CNN-LSTM model achieves optimal comprehensive evaluation indices in one-step prediction and possesses excellent tracking capability for inflection points and amplitude fluctuations of time series data. Although the prediction accuracy decreases gradually with the increase in prediction steps, the model can still effectively characterize the evolutionary trend of pump operating states, and its overall prediction performance is significantly superior to that of single models. This study provides model support and technical reference for the health evaluation, early fault alarm, and maintenance optimization of deep-sea mineral lifting pumps in offshore trials.

The inducer is a key component of aerospace centrifugal pumps, and its performance directly affects cavitation characteristics and overall efficiency of the pump. Based on the theory of reverse engineering, a parametric intelligent optimization (PIO) platform for the inducer was constructed, achieving precise extraction of geometric parameters, numerical simulation, and automatic optimization design. The head of the inducer was chosen as a constraint; the maximum hydraulic efficiency and the minimum critical net positive suction head (NPSHr) were chosen as the objectives, and the Latin hypercube sampling method and the Particle Swarm Optimization algorithm were used to perform multi-objective optimization on the inducer. The results demonstrate that the proposed reverse reconstruction and optimization framework achieves high predictive accuracy, with relative errors of only 1.54

Marine pumps are critical components of ship power systems, whose operational stability and noise characteristics are strongly influenced by unsteady internal flow. Under complex operating conditions, flow unsteadiness induces hydraulic excitation and pressure pulsations, leading to increased vibration, noise, and reduced service reliability. This study numerically simulated the full flow field of a marine pump with balancing holes based on the rotational curvature modified shear-stress transport with scale-adaptive simulation to investigate the hydraulic excitation and flow features under different operating conditions. Meanwhile, combined with the entropy production theory and vorticity transport equation, the unsteady flow mechanism inside the pump was evaluated. The results show that the pressure pulsations at the volute tongue have a primary frequency of 1f(BPF) with secondary frequencies of 2f(BPF) and 3f(BPF). The rotor-stator interface between the leading edge of the blade and the leakage chamber, the volute tongue, and the diffusion section has a strong intensity of pressure pulsations, and the entropy production rate is high in these zones. Moreover, the vortex stretching and the Coriolis force play a major role in the generation and development of flow passage vortices in the impeller, while the vortex viscous dissipation has a minor effect. These findings provide guidance for the optimal design and vibration-noise reduction of marine pumps.

Centrifugal fuel pumps, as a key component of aeroengines, directly impact the performance and reliability of the engine. In response to this, this paper proposes a multidisciplinary optimization design method suitable for centrifugal fuel pumps to enhance hydraulic performance and structural strength. This method combines artificial neural networks and particle swarm optimization to adjust the distribution of blade wrap angle and thickness, with constraints on head coefficient and maximum impeller stress, aiming to maximize efficiency and minimize deformation. The optimization results show a 4.4

Inflow distortion has long been recognized as a critical factor contributing to increased energy consumption in large-scale pumping systems worldwide. When combined with the inherent circumferential asymmetry of double-suction pumps, the resulting unsteady effects further impair operational stability. However, the associated coupling mechanisms under valve-inflow conditions have not been systematically investigated or quantitatively characterized. This study addresses this gap by employing entropy generation theory and vortex dynamics analysis to investigate the energy-loss mechanisms of double-suction pumps subjected to valve-induced inflow distortion. Results show that complex shedding and standing vortices develop downstream of the valve, with dissipation concentrated within 1D0(where D0 is the water supply pipe diameter) of the valve axis and fully dissipated by turbulence at 2.5D0. At high flow rates, these structures reduce efficiency by 3.4% and head by 3.7%, modify the relative flow angle near the impeller leading edge and suction surface, intensify impact losses and induce separation, and generate a new pulsation frequency of 0.13fn in the suction chamber. The findings validate the applicability of entropy-generation analysis for quantifying local energy dissipation, clarify the valve-pump coupling mechanisms, and provide practical guidance for improving the hydraulic efficiency and operational reliability of large pumping stations.

To investigate the influence of different three-way pipe angles on internal flow noise characteristics, this study employs large eddy simulation (LES) and the acoustic finite element method (FEM) to conduct numerical simulations of the flow field and internal acoustic field for three different pipe angles (30 degrees, 60 degrees, and 90 degrees). The results indicate that as the angle of the three-way pipe increases, pressure pulsation decreases along the main pipe direction while increasing along the branch pipe direction. The low-speed vortex region near the lower wall of the main pipe outlet and the high-speed vortex region near the lower wall of the branch pipe outlet are significantly weakened. The internal flow noise energy at the main pipe inlet/outlet and branch pipe outlet is primarily concentrated in the 1-10 Hz and 1-20 Hz frequency ranges, respectively, with the branch pipe outlet exhibiting slightly higher sound pressure levels than the main pipe inlet/outlet. Moreover, as the three-way pipe angle increases, the overall sound pressure level (OSPL) at the main pipe outlet shows the most significant reduction with a decrease in 12.3%. Bionic optimization of the 90 degrees three-way pipe further reduces an 11.9% reduction in the OSPL at the branch pipe outlet. Published under an exclusive license by AIP Publishing. https://doi.org/10.1063/5.0275508

This study experimentally investigates the effects of inlet gas volume fraction (C=0.0 %-0.75 %) on vibration damping and noise reduction in a marine centrifugal pump. Tests were conducted at three flow rates (0.8Qd, 1.0Qd, and 1.3Qd), with measurements of external characteristics, outlet pressure pulsation, vibration, and outlet noise. Results show that when the inlet gas volume fraction is below 1 %, the pump head decreases by less than 0.20 %, and the efficiency reduction is less than 0.22 %, indicating minimal performance loss. An optimal inlet gas volume fraction of 0.50 % under 0.8Qd and 1.0Qd, and 0.75 % under 1.3Qd, yields maximum vibration damping. Specifically, the overall vibration velocity level at the pump's base foot (M3) decreases by 0.26 dB, 0.33 dB, and 1.63 dB under the three flow rates, respectively. At the first axial passing frequency (1fAPF), the vibration velocity level decreases by up to 4.60 dB, 1.87 dB, and 0.98 dB, while at the first blade passing frequency (1fBPF), it decreases by 3.13 dB, 2.53 dB, and 10.92 dB, respectively. In terms of noise, the overall sound pressure level (OASPL) at the outlet is reduced by up to 2.76 dB (under 1.3Qd). Coherence analyses confirm that uniform gas distribution in the impeller flow passages weakens rotor-stator interaction, thereby reducing both vibration and noise, particularly at low characteristic frequencies. These findings provide a practical basis for improving the stability and acoustic performance of marine centrifugal pumps through controlled inlet gas injection.

Tip leakage cavitating flow under a dynamic boundary remains a critical challenge in axial hydraulic machinery; research characterizing such cavitating flow with acceptable accuracy is currently limited. In this study, a flat plate hydrofoil undergoing sinusoidal pitching motion around the mid-chord point is employed to simulate tip leakage cavitating flow under dynamic boundaries. The shear stress transport k-omega model and the Zwart-Gerber-Belamri model are applied to investigate the cavitation patterns and vortex structures within the tip clearance under pitching motion. The results indicate that the tip leakage cavitating flow involves the tip leakage vortex (TLV), the tip separation vortex, and the induced vortex, with the TLV being the dominant vortex structure. The TLV-induced tip leakage vortex cavitation (TLVC) is the only cavitation pattern within the tip clearance. The TLV and TLVC exhibit significant periodicity during the pitching process. During the upstroke phase, the TLVC intensity gradually decreases, the streamwise vorticity near the TLVC gradually increases, and the velocity circulation initially decreases and then increases. However, during the downstroke phase, the changes in these features are opposite to those in the upstroke phase. In addition, at the same angle of attack for upstroke and downstroke phases, the TLV and TLVC intensity are greater in the downstroke phase. Moreover, a wandering cavity appears in the TLVC during the upstroke phase, while the TLVC has more integral shape during the downstroke phase.

High-pressure liquid hydrogen pumps are the key equipment for the large-scale and efficient transfer of liquid hydrogen. Accurately predicting the in-cylinder heat transfer is crucial for optimizing the performance of high-pressure liquid hydrogen pumps. This paper numerically studies the unsteady heat transfer and fluid flow in the cylinder of a reciprocating liquid hydrogen pump, considering thermal conduction in the cylinder wall. The thermal conduction process in the cylinder wall of the high-pressure compression cylinder and its impact on the temperature distribution and heat flux are analyzed. Additionally, the effects of cylinder wall materials on temperature distribution, fluid flow, and heat transfer are studied. Finally, the calculation results are compared with the predictions of three existing empirical correlations for in-cylinder heat transfer. Among these, Annand's correlation accurately predicts the Nusselt number in comparison with the calculation results. This work can provide theoretical support for the thermal design and structural optimization of high-pressure liquid hydrogen pumps.

The current arterial signal coordination models only target through traffic or critical traffic, resulting in fairness issues for traffic in other directions. Moreover, these models fail to achieve system optimality between intersections along the arterial. To address these problems, this paper establishes an arterial signal coordination optimization model based on all-direction pairs of adjacent intersections. The model takes the minimum weighted green wave band center offset of all-direction pairs at the intersections as the objective function. The optimization variables are the cycle length, offset, and phase sequence. The phase sequence structure adopts the ring-and-barrier structure, and the phase sequence optimization includes not only the main road but also the minor road intersecting with it. The model is an integer linear programming model, and it optimizes all-direction pairs of the upstream and downstream intersections. By analyzing the spatiotemporal diagram of the intersections, constraints are established for the phase sequence of the main road and intersecting roads. Through optimization of the offset and phase sequence, the coordination of flow direction pairs between upstream and downstream intersections can be optimized to improve the overall traffic fairness of the arterial.

During the operation of non-clogging pumps, the flexible long fiber is prone to clogging and winding during the flow process, which can result in damage to the non-clogging pump, so a numerical simulation method of a solid–liquid two-phase flow in a non-clogging pump with a flexible long fiber is proposed in this paper. The unsteady numerical simulation of the two-phase flow of a single flexible fiber with different densities, lengths and diameters in a double-blade non-clogging pump was carried out to study the influence of fiber parameters on fiber transport capability. The results show that at a density of 920 kg/m3, 300 kg/m3 and 732 kg/m3, the transport capability of flexible fibers decreases successively, and the transport time T0 is 0.32 s, 0.36 s and 0.48 s, respectively. The transport capability of flexible fibers with a length of 150 mm, 200 mm and 250 mm decreases successively, and the transport time T0 is 0.34 s, 0.48 s and 0.96 s, respectively. The transport time T0 is 0.48 s when the fiber diameter dp is 5 mm. When the fiber diameter dp is 7.5 mm, the transport time T0 is 0.51 s. When the fiber diameter dp is 10 mm, the fiber transport capability of the non-clogging pump decreased significantly, and the transport time T0 is 0.68 s. The fiber length has the most obvious effect on fiber transport capability, followed by the fiber diameter and fiber density.

The influence of a different blade number, blade wrapping angle and blade outlet angle on flexible fiber passing performance is analyzed numerically with CFD-DEM coupling. The results demonstrate that a non-clogging pump with two blades exhibits superior passing performance compared to the non-clogging pump with three blades. Specifically, when the fiber length L is 150 mm, the passing performance of the pump with different wrapping angles is 270° > 240° > 300°, from highest to lowest, and the transport time T0 is 0.27 s, 0.34 s, 0.46 s, respectively. When the length L is 200 mm, the passing performance is 240° > 270° ≈ 300°, and the transport time T0 is 0.48 s, 0.55 s, and 0.55 s, respectively. When the fiber length L is 250 mm, the passing performance is 240° ≈ 270° > 300°. When the fiber length L is 150 mm, the passing performance of the pump with different outlet angles is 15° > 25° > 20°, and the transport time T0 is 0.17 s, 0.27 s, and 0.34 s, respectively. When the fiber length L is 200 mm, the passing performance is 25° > 15° ≈ 20° and the transport time T0 is 0.26 s, 0.50 s, and 0.48 s, respectively. When the fiber length L is 250 mm, the passing performance is 25° > 15° > 20°, and the transport time T0 is 0.31 s, 0.54 s and 0.96 s, respectively.

Venturi tube can be used to measure the flow rate of stable single-phase fluid, which plays an important role in chemical industry, energy, aerospace and other fields. Due to the complex physical properties of cryogenic fluids, it is of great significance to study the cavitation characteristics of cryogenic fluids for practical engineering. In this paper, the modified Zwart cavitation model is used to study the evolution characteristics of cryogenic cavitation in Venturi tube and its relationship with turbulent kinetic energy under different pressure ratios by using dimensionless number P-r instead of cavitation number. The P-r value affects the development of cavitation to a large extent. When P-r = 1.3, cavitation is in a stable development mode. When P-r = 2.3, the development mode of cavitation changes from steady state to dynamic state. The temporal and spatial correlation between cavitation and vortex structure is studied by Q-criterion, and the geometric similarity between cavitation cloud and vortex structure in the development process is analyzed. The entropy production caused by velocity gradient change, turbulent dissipation and wall shear stress is further analyzed by entropy diagnosis method. The results show that the change of P-r value plays a leading role in the distribution of entropy production, and the generation and collapse of cavitation in the evolution process also have a great influence on the distribution of entropy production.

High-speed centrifugal pumps are widely used in several industries due to their high efficiency and small footprint. In actual applications, there are issues such as low operational efficiency and a small high-efficiency flow interval; particularly, the leakage occurring in the impeller channel gap presents a significant barrier to the pump’s performance and stability. This study takes the fully open impeller miniature high-speed centrifugal pump as the object and uses a numerical simulation calculation method. The objective of this research endeavor is to analyze the effects of different flow conditions on a high-speed centrifugal pump’s external characteristics, flow field characteristics, and energy loss. The findings indicate that lobe top clearance exerts a substantial impact on the efficiency of high-speed centrifugal pumps. Increasing the lobe top clearance will result in a reduction in pump head and efficiency, particularly under high flow conditions. The lobe top clearance has a significant impact on the complexity of the flow in the impeller, particularly the flow close to the suction surface of the impeller, according to an analysis of the flow field characteristics. The energy loss analysis further confirms the importance of reducing lobe top clearance for improving pump performance and reducing energy loss. These results provide valuable guidance for optimizing centrifugal pump designs with lobe top clearance.

As the key control equipment for the transmission of fluid medium, processing valves are widely used in the transmission systems of fluid medium in energy, chemical industry, metallurgy and other fields, which play important roles in the stability and reliability of the system operation. When the flow cross-section is operated in a sudden change, the pressure decreases rapidly at the downstream, which leads to the cavitation in the processing valves. Cavitation makes serious erosion and damage on the valve core and pipeline surface, which leads to the leakage and noise problems in processing valves. This seriously affects the regulation performance and lifetime of processing valves. In this article, numerical simulations were carried out to investigate the transient cavitation in a model butterfly valve. By considering effects of local pressure on formation of cavitation, a modified model for calculating the diameter of cavitation bubbles was derived. Effects of valve opening degree was investigated on the dynamic evolution of cavitation by analyzing formation, development and collapsion of cavitation. The generation, development and collapsion of single cavitation bubble was obtained and discussed in details to state the interaction between vortices and cavitation. Attached and quasi-periodic cavitation were observed and analyzed in detail as well at different valve opening degrees.

This article addresses the painting process in the lock manufacturing process and designs a dedicated automatic painting production line for locks. By applying this automatic painting system, it can significantly improve the painting process in lock production, enhance product quality and production efficiency, and ensure the health and safety of operators. This has a positive impact on promoting the development of the lock manufacturing industry.

Considering the cryogenic cavitation characteristics, a numerical calculation method applicable to the cryogenic cavitation flow of multistage liquid-sealing impellers of liquid oxygen turbine pump was proposed, and the feasibility by using the experimental data under liquid nitrogen was verified. And the cryogenic cavitation flow and sealing characteristics inside the multistage liquid-sealing impellers were studied numerically. The results show that compared to the liquid nitrogen test values, the maximum calculated deviation for the rear chamber temperature and pressure is 8.2% and 6.7% respectively, and the numerical calculation method is feasible. The volume of vapor phase in multistage liquid-sealing impellers is about 2～3 times of the volume of liquid phase, the primary liquid-sealing impeller plays the main sealing performance, the secondary liquid-sealing impeller is in the low pressure vapor phase environment,some working conditions have local pressure holding in the back cavity, the number or diameter of drainage outlet can be increased appropriately to avoid pressure holding. The flow field has a temperature variation from-4 K to 9 K. The highest and lowest temperatures are located at the primary and secondary liquid-sealing impellers, reflecting the thermodynamic effect of cryogenic cavitation. The high entropy production area in the flow field is mainly distributed in the primary liquid-sealing impeller, which is the main region of energy loss, and the pulsating velocity entropy production ΔSD’ is the main source of entropy production. The Multistage liquid-sealing impeller forms a stable vapor-liquid intersection at the primary liquid-sealing impeller, and the radius of phase change increases from working condition Ⅰ to Ⅳ. The discharge through the drainage outlet is all vapor-phase medium, and the total flow rate is between 0.1 kg/s and 0.44 kg/s,which is small and effectively prevents the leakage of liquid oxygen.