Search Results (20)

Centrifugal pumps serve as key equipment in water conveyance systems. Different tee inlet structures distort the internal inflow field, induce extra hydraulic losses and reduce system energy efficiency, since pump power consumption and operational stability are highly sensitive to tee pipeline layouts. Pressure pulsation directly reflects internal flow disorder and reveals the root causes of hydraulic performance attenuation, so it is adopted as the core analytical tool in this work. Using the Shear Stress Transport (SST) k-ω turbulence model, numerical simulations are carried out on an 80 mm centrifugal pump with four inlet structures: straight pipe (SP), reducing tee (RT), reducing wye (RW), and asymmetric reducing wye (ARW). Combined with pressure pulsation signals, this study reveals the propagation rules of flow disturbances induced by tee inlet structures and their inherent energy loss mechanisms. The results show that tee inlet structures barely affect overall pump performance, except RT, which reduces the hydraulic head by 0.44 m and efficiency by 1.47%, accompanied by higher power consumption. Impeller pulsation intensity increases from the leading edge to the trailing edge, with the mid-passage leading edge being the most sensitive region. Impeller spectra are dominated by low-order shaft frequency harmonics, while volute signals are dominated by blade frequency (BF) harmonics. Different tee inlet structures have little impact on circumferential volute pulsation but significantly alter flow characteristics at the volute tongue and outlet diffuser, where 2BF becomes the primary dominant frequency. Disturbance propagation laws differ greatly between the impeller and downstream volute. Centered on low-energy pump system design, this study provides theoretical support for inlet pipeline optimization and energy-saving operation of municipal, industrial, marine and water conservancy pumping facilities. Full article

Liquefied natural gas (LNG) submersible centrifugal pumps are critical components in marine energy transportation systems, and fault-induced degradation may threaten operational safety, transfer reliability, and maintenance efficiency. However, condition monitoring and fault diagnosis often rely on heterogeneous multi-source data, where redundant information, unequal channel sensitivity, and inter-signal coupling may obscure discriminative fault features. To address this challenge, this paper proposes a hierarchical multi-source condition monitoring and fault diagnosis framework for LNG submersible centrifugal pumps by integrating an Entropy-Weighted Sensor Selection Method (EWSSM) with a hybrid convolutional neural network (CNN)–Transformer model. Functional information is used for front-end abnormality screening, while selected response signals are used for fault category recognition. EWSSM evaluates channel contribution and suppresses redundant inputs to construct a compact fault-sensitive input space. The CNN–Transformer model combines local feature extraction with global dependency modeling to identify complex fault patterns. A laboratory-scale fault simulation platform was established, and vibration, acoustic, internal pressure-pulsation-related response information, and operating parameter data were collected under ten operating states. Experimental results show that the proposed framework achieves effective abnormality screening and accurate fault diagnosis, with an average classification accuracy of 98.73% over repeated experiments. Covariance-difference analysis further provides interpretable evidence for condition assessment by revealing fault-related multi-source response redistribution. The proposed framework provides an effective, intelligent monitoring and diagnosis solution for LNG submersible centrifugal pumps and supports reliability-oriented operation and maintenance of marine energy transportation equipment. Full article

Low-frequency broadband vibration isolation poses a critical limitation for marine power equipment, as conventional passive isolators fail below 50 Hz. Targeting the 10–315 Hz band (dominant for marine pumps), this study proposes a passive isolator integrated with a disk-like acoustic black hole. This article aims to address the core engineering issues in the operating frequency band of marine power equipment, specifically the failure of traditional passive vibration isolators in low-frequency vibration isolation and the insufficient reliability of active/hybrid vibration isolation schemes in the marine high-salt fog environment. Meanwhile, it breaks through the theoretical bottleneck of traditional acoustic black hole (ABH) structures, which have a high cut-off frequency and a weak low-frequency vibration suppression capability. A passive vibration isolator integrating a disk-shaped ABH and a damping layer is proposed to achieve efficient low-frequency broadband vibration isolation. The modal participation factor was calculated via finite element modal superposition to identify the dominant low-frequency modes, and a high-fidelity dynamic model was established to analyze the key ABH parameters and damping layer configurations. A prototype validation was conducted on an ISG vertical centrifugal pump acceleration response. The results show that the isolator (L_ABH = 95 mm, h_uni = 10 mm, disk-shaped damping layer) achieves 8.87 dB and a higher vibration level drop of 17.52 dB in 10–315 Hz and 315 Hz–10 kHz, respectively, than non-ABH designs, with simulation–experiment errors of less than 5%. The ABH–dynamic vibration absorber synergistic mechanism overcomes the low-frequency limitation of conventional passive isolators, providing a reliable solution for marine power equipment vibration suppression. Full article

The marine centrifugal pump is one of the most energy-intensive pieces of equipment in ship auxiliary machinery, and the efficient design of its hydraulic components can effectively reduce the total energy consumption of the ship system. Aiming at the complex three-dimensional twisted blade profile structure of the marine centrifugal pump, this paper optimized the clonal selection algorithm and constructed an automatic hydraulic optimization design method for the high-efficiency centrifugal pump impeller. Considering the multi-condition operation characteristics of the marine centrifugal pump, a performance test platform for the marine centrifugal pump was built, and the actual operating conditions of the model pump were tested to obtain its performance characteristics under operating conditions. The numerical simulation method was employed to capture and analyze the internal flow field and flow characteristics of the model pump. Addressing the design challenges of the marine centrifugal pump impeller, which involve multiple parameters with significant interactions, a traditional clonal selection algorithm was enhanced using a Slime Mold Algorithm, and a hybrid Clonal Selection Algorithm integrated with Slime Mold and Tangent Flight mechanisms was established. Based on the MATLAB and ANSYS platforms, an automated hydraulic optimization design framework for the centrifugal pump impeller was established. Using the optimized clonal selection algorithm, with the operational efficiency of the model pump as the optimization objective and controlling ten key geometric parameters of the blade profile through Bézier curves, the blade profile optimization design was achieved. The pump hydraulic efficiency under the rated flow condition increased by 7%. The unsteady internal flow efficiency of the optimized marine centrifugal pump was significantly improved. The blade optimization alleviated flow separation phenomena on the tangential surface of the impeller and in partial regions of the volute, reduced the flow loss area, and significantly decreased overall flow losses. Full article

Marine vertical centrifugal pump vibration severely impacts equipment reliability and ship structural integrity, with low-frequency vibration being a key challenge for traditional passive isolation systems. To address this, this study aims to optimize the pump base’s vibration isolation performance by integrating symmetrically distributed acoustic black holes (ABHs) and locally resonant metamaterials. A combined numerical and experimental approach was adopted: an H-shaped ABH-coupling plate dynamic model was established and validated, followed by parametric evaluation of base structures, ABH parameters (length, l_ABH), damping layer configurations, and metamaterial arrays. Experimental tests were conducted using simulated pump excitation on the optimal prototype. The results show the optimal configuration—symmetrical ABH (l_ABH= 100 mm) with a full damping layer and 3 × 3 metamaterial array—achieves 11.97 dB low-frequency and 22.01 dB high-frequency vibration suppression, forming a 24.8–27.6 Hz bandgap and 7.43 dB isolation at characteristic frequencies, with an overall 13% performance improvement. This work verifies the feasibility of the symmetrical ABH–metamaterial hybrid system, providing a novel technical solution for high-performance vibration-noise reduction in marine power equipment. Full article

Designed to mitigate the significant low-frequency vibration and noise inherent in conventional marine centrifugal pump systems, the magnetic levitation pump constitutes a novel form of centrifugal pump employing active magnetic bearing technology. While this fully levitated design effectively enhances vibration and noise performance, it results in the complete immersion of the rotor within a confined fluid domain, which contains narrow fluid clearances. This poses significant challenges for the accurate computation of rotor wet modes, which is crucial for the structural design of the rotor system to avoid the resonance induced by flow. Despite exerting a substantially greater influence on rotor wet modal characteristics than unconfined domains, the analysis of rotors under confined fluid conditions has received comparatively little research attention. This study focuses on two types of magnetic levitation pump rotors. From the perspective of analytical modeling, an improved analytical method for wet modal computation based on added mass correction is proposed. The validation of this method included examining two distinct computational approaches for the added mass, the thickening treatment for axially elongated disk components, and the methodology for implementing disk equivalent density. Based on this foundation, wet modal analysis was performed on both rotors utilizing the proposed analytical method, alongside acoustic fluid–structure interaction simulations. The results indicate that for the first bending mode, the errors between the analytical and experimental values are 1.2% and 4.1%, respectively, while the discrepancies between the simulated and experimental values are 0.1% and 3.2%. Finally, regularity analysis was conducted on the wet modal characteristics of the rotor under confined water, considering various fluid clearances. The results reveal that the first three bending modes generally exhibit an increasing trend with the enlargement of the fluid clearance, with a triple-size annulus serving as a transition point. However, increasing the annulus size does not always elevate the modal frequencies above their initial values. This study contributes to understanding the influence mechanisms of confined water on the wet modal properties of magnetic levitation pump rotors. Furthermore, the proposed analytical method improved computational efficiency for the early design stages of water-immersed rotors, alongside a model of greater accuracy essential for magnetic bearing control. Full article

Centrifugal pumps are essential to modern marine engineering systems for fluid transport. This study is to analyze the typical failure causes of sediment erosion and energy dissipation in a multi-stage centrifugal pump with different blade installation angles α using numerical simulation approach and on-site testing. Three different schemes with α = 0°, 10.85°, and 21.7° were designed. The installation angle of the blade influenced sediment erosion and energy dissipation through three key aspects: turbulent flow, particle motion, and wall roughness. Turbulent and friction dissipation, which are related to the blade angle and sediment erosion, are the leading causes of the pump failure. The symmetrical blade installation, turbulence intensity, particle impact velocity, and wall friction inside the unit were the highest, resulting in the most severe turbulence loss, wall loss, and sediment erosion under this scheme, with the maximum friction loss being 320 W·m⁻³·K⁻¹. Complex turbulence intensifies the intensity of particle motion, with the maximum sediment erosion rate E = 0.000052 kg·m⁻²·s⁻¹. Compared to Plan 1 and Plan 3, the performance can be improved by more than 20% and 23%, respectively. There was a positive correlation between the friction loss and erosion rate. The research presented in this study provides a novel perspective on the operation of a pump to prevent sediment erosion failure. Full article

Given that cryogenic pumps on liquefied natural gas (LNG) carriers are prone to cavitation under complex operating conditions, this paper examines the inducer of an LNG centrifugal pump to uncover how the inducer geometry affects both the cavitation behavior and internal flow-induced excitation at −163 °C. Through detailed numerical simulations, we evaluate the cavitation performance and flow excitation characteristics across a range of inducer designs, systematically varying the blade count, inlet and outlet angles, and blade wrap angle. Our results show that reducing the number of blades, together with properly optimized inlet/outlet and wrap angles, significantly enhances the cavitation resistance. These findings provide a solid theoretical basis and practical guidance for the engineering optimization of LNG ship pumps. Full article

The vertical inline pump, a single-stage centrifugal pump with a bent elbow inlet, is widely used in marine engineering. The unique water inlet passage combined with uneven inflow at the impeller inlet tends to form an inlet vortex and secondary flow area, which reduces performance and causes vibration. To predict the performance of the elbow inline pump, this study uses spline curve fitting for the centerline and cross-sectional shape of the elbow passage. With four elbow inlet variables from experimental design as the input layer and targeting efficiency under pump operating conditions, a pump performance prediction model based on an improved sand cat swarm optimization algorithm combined with a BP neural network (MSCSO-BP) is proposed. Six test functions are used to effectively test the improved sand cat swarm optimization algorithm. The results show that compared to the unimproved algorithm, the improved algorithm has significantly faster convergence speed, shorter parameter optimization time, and higher accuracy. For more demanding multidimensional test functions, the improved optimization algorithm can more accurately find the optimal solution, enhancing the prediction accuracy and generalization ability of inline pump performance. This provides a more effective engineering solution for the design and optimization of inline pumps. Full article

Wide-flow centrifugal pumps are widely used in marine, petrochemical, and thermal power plants because of their good hydraulic performance. To enhance the hydraulic performance of wide-flow centrifugal pumps and thereby reduce energy consumption, in this study, an automatic optimization system for rotating machinery based on genetic algorithms was employed. Initially, a detailed description of the centrifugal pump model and the optimization system was provided. Subsequently, sensitivity analysis of key parameters was conducted through design of experiments (DOEs), identifying the primary factors influencing the pump performance. This research demonstrated that the blade wrap angle, as well as the leading and trailing vane exit angles of the front and back shrouds, are crucial factors affecting the performance of the centrifugal pump, with the blade wrap angle exerting a particularly significant impact on pump efficiency, contributing up to 83.6%. After optimization, the pump’s head increased by 1.29%, and the efficiency improved by 2.96%. The flow field of the optimized pump was significantly improved, with enhanced fluidity, achieving higher head and efficiency at a lower torque. Additionally, the pumping performance was augmented with an enhanced diffuser capacity in the pump volute, leading to increased exit pressure energy, while the turbulent kinetic energy and entropy production losses were significantly reduced. Under various operating conditions, the entropy production losses at the pump walls were all decreased, and the total mechanical energy within the impeller showed an increasing trend from the inlet to the outlet, resulting in lower energy consumption. In this paper, a reference is provided for further enhancing the hydraulic performance of centrifugal pumps in the future. Full article

Due to the effects of swing motion, the performances and internal flow characteristics of marine centrifugal pump undergo some unsteady variations in the marine environment. The hydraulic test system with six degree of freedom parallel motion platform is established to study the pump performance characteristics at the different heel angles of steady roll position and pitch position. The pump head gradually decreases as heel angle increases. The pump head has decreased by 7% to reach the minimum at the 15° heel angle of roll position. At the same heel angle, the head at the roll position is lower than that at the pitch position under the rated flow condition. The fluid in the impeller passage is subjected to the additional inertial force of roll motion or pitch motion under unsteady swing motion, inducing some flow bias phenomena in the velocity field. The unsteady development of flow velocity induces the intense vortex motion, and the shedding and dissipation of interblade vortices are affected. The periodic flow-induced pulsation characteristics obviously appear in the impeller passage. The pulsation periodicity and pressure amplitude are influenced due to the swing motion. The pitch motion induces the greater hydraulic excitation and fluid-induced vibration amplitude. In addition to the pressure pulsation at the low frequencies, the pulsation amplitude at 20 times the shaft frequency is evident under pitch motion. Full article

The purpose of this work was to test a new setup to pump water with entrained air for application in gas fermentation. A mixed flow, where gas is contained in a liquid to be pumped, rapidly reduces the efficiency of a conventional pump, due to the compressibility of the gas. It is not always possible to degas the fluid, for instance in gas fermentation, which is preferably carried out in tubular reactors (loop fermenters) to achieve a high conversion rate of the gaseous feedstocks. Method: In this work, a rim-driven thruster (RDT) was tested in a lab-scale, cold flow model of a loop reactor with 5–30% (by volume) of gas fraction (air) in the liquid (water) as alternative propulsion element (6 m total pipe length, ambient temperature and pressure). As a result, it was found that the RDT, in connection with a guiding vane providing swirling motion to the two-phase fluid, could pump a mixed flow with up to 25.7% of gas content (by volume) at atmospheric pressure and 25 °C and 0.5 to 2 m/s flow speed. In conclusion, an RDT is advantageous over a classic propulsion element like a centrifugal pump or axial flow pump for transporting liquids with entrained gases. This article describes the potential of rim-driven thrusters, as known from marine propulsion, in biotechnology, the chemical industry, and beyond, to handle multiphase flows. Full article

Centrifugal pumps are essential fluid transfer devices in marine engineering. As the two most critical components of a centrifugal pump, the dynamic–static interference between the volute and the impeller makes the flow near the cutwater highly unstable, with significant and erratic pressure pulsation, which seriously affects the stability of the operation. The impeller can be improved by cutting the hub, which helps stabilize the flow and reduce pressure pulsation near the cutwater, thus minimizing hydraulic loss. In this study, four different cutting angles were applied to the impeller hub. Computations are conducted using large eddy simulation to analyze the flow and pressure pulsation near the cutwater. Compared to the prototype pump, the modified impeller exhibits a significant reduction in pressure gradient near the blade outlet close to the cutwater. The modified impeller also shows a more uniform flow and lower amplitude of pressure pulsation. Furthermore, under various flow conditions, the centrifugal pump with the modified impeller exhibits lower hydraulic loss compared to the prototype pump, indicating that this method effectively suppresses hydraulic loss. Full article

Marine centrifugal pumps (MCPs) are widely used in ships, so it is important to identify their status accurately for their maintenance. Due to the influence of load, friction, and other non-linear factors, the vibration signal of an MCP shows non-linear and non-stationary characteristics, and it is difficult to extract the state characteristics contained in the vibration signal. To solve the difficulty of feature extraction of non-linear non-stationary vibration signals generated by MCPs, a novel MCP frequency domain signal feature extraction method based on a stacked sparse auto-encoder (SSAE) is proposed. The characteristic parameters of MCP frequency domain signals are extracted via the SSAE model for classification training, and different statuses of MCPs are identified. The vibration signals in different MCP statuses were collected for feature extraction and classification training, and the MCP status recognition accuracy based on the time domain feature and fuzzy entropy feature was compared. According to the test data, the accuracy of MCP status recognition based on the time domain feature is 71.2%, the accuracy of MCP status recognition based on the fuzzy entropy feature is 87.7%, and the accuracy of MCP status recognition based on the proposed method is 100%. These results show that the proposed method can accurately identify each status of an MCP under test conditions. Full article

The biomimetic surface with Space-V grooves can effectively reduce flow resistance and noise. Our investigation was in order to further enhance the drag reduction and noise reduction performance of a marine centrifugal pump with Space-V-groove-shaped biomimetic surfaces. A regression equation was established with response surface methodology between the total sound pressure level and the height (h), width (s), and spacing (b) of the biomimetic groove structure. The interaction effects of various parameters on the total sound pressure level were analyzed, and the parameter range was determined at the lowest total sound pressure level. The hydraulic performance and interior noise of the model before and after optimization were compared. The results showed that the total sound pressure level initially decreased and then increased with increasing groove height. Similarly, with an increase in groove width, the total sound pressure level decreased at first, then increased. When the height of the bionic groove is 0.5–0.7 mm, the groove width is 0.4–0.7 mm, the groove spacing is 0.7–1.3 mm, and the total sound pressure level of the centrifugal pump is the smallest, which is 180–182 dB. On the other hand, the total sound pressure level increased as groove spacing increased. Through the use of an optimized Space-V groove model, under rated working conditions, the model head is increased by 0.27 m and the efficiency is increased by 1.21%. In addition, the optimized model has excellent drag and noise reduction performance, with the drag reduction rate of 3.73% and noise reduction rate of 1.81%, which are, respectively, increased by 0.87% and 0.45% compared with before optimization. The performance of centrifugal pumps for ships can be greatly improved. Full article