Effect of return channel on performance and pressure fluctuation of pump turbine

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(10)

Published: Oct. 1, 2024

To stabilize the operation of pumped storage power station, an orthogonal experimental design was proposed to optimize return channel with splitter blades pump turbine. The calculation results various models under multiple operating conditions indicated that inlet distance a1 and blade number z considerably affect efficiency flow pattern in passage. optimal scheme improved by nearly 3% at 0.6Qd. Savitzky–Golay filtering method Fast Fourier Transform were used analyze unsteady characteristics turbine model. amplitude pressure pulsations passing frequency vaneless space interference zone between guide vane reduced considerably, pulsation decreased 50%, 48%, 20% for 0.6Qd, 1.0Qd, 1.1Qd conditions. A Continuous Wavelet signals during shutdown transition process. optimization their corresponding passages suppressed high-amplitude unit stable station.

Language: Английский

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Energy conversion and performance analysis of the submerged waterjet relative to the conventional waterjet in self-propulsion

Ocean Engineering, Journal Year: 2025, Volume and Issue: 326, P. 120699 - 120699

Published: March 10, 2025

Language: Английский

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Optimization of organic Rankine cycle turbine expander based on radial basis function neural network and nondominated sorting genetic algorithm II

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(3)

Published: March 1, 2025

The organic Rankine cycle (ORC) represents an effective technology for the recovery of medium- and low-temperature waste heat. Within this system, turbine expander plays a critical role in determining reliability efficiency overall process. This paper presents structural optimization approach that integrates radial basis function (RBF) neural network model with nondominated sorting genetic algorithm II (NSGA-II), considering isentropic power ORC using R1233zd(E) as objectives. Utilizing design-of-experiments method conjunction simulation, high-precision RBF was developed trained. external performance internal flow characteristics original optimized are compared. In addition, entropy production is used to locate quantitatively evaluate energy losses. results indicate exhibits high predictive accuracy, correlation coefficient (R2) exceeding 0.9 both objective functions. process significantly enhanced expander. Under Q/Qd = 1.2, improved by 6.13% 33.96%. can accommodate larger range variations, increasing efficient operation region 1.28 times. loss decreases average over 17% due suppression vortices at leading edge outlet impeller. work provides valuable reference improving expanders heat other application fields.

Language: Английский

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On energy conversion mechanism of a marine submerged waterjet

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(3)

Published: March 1, 2025

The submerged waterjet (SWJ) is a novel marine propulsor for surface ships, which shows remarkable energy performances in mixed-use profile. Less research has been done to reveal the mechanisms of its distinguished and propulsion performances. Based on flux balance theory, this paper proposes method analysis conversion process SWJ system, where link established between performance quantitative evolution components occurring both internal external flows through control volume system. detailed investigation indicates that various interactions, among rotor, stator duct, exhibit different impacts enhancing overall duct majorly changes working environment rotor from flow operation ones. After adding shaft power increases sharply, due increased pressure distribution domain. Afterward, system can experience stronger work into axial kinetic flux, enables have greater potential generate larger thrust. As post-stator, it improves open water efficiency dominantly enhancement hydraulic efficiency. In detail, positive impact post-stator mainly achieved by increasing proportion promoting transversal ones pump inner For around downstream also plays significant role improving hub vortex as well stability tip leakage vortex. A more stable field one important prerequisites reducing vibration noise Another enhance generating additional thrust guide vanes reduce drag at same time.

Language: Английский

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Hydraulic Characteristics of Pumped Storage Units from Startup to No-Load Before Synchronization Based on PID Control

Energy, Journal Year: 2025, Volume and Issue: unknown, P. 136747 - 136747

Published: May 1, 2025

Language: Английский

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Effect of protrusion structure on the performance of an advanced hydrodynamic cavitation reactor: An entropy-based analysis

Ultrasonics Sonochemistry, Journal Year: 2025, Volume and Issue: 119, P. 107392 - 107392

Published: May 17, 2025

Hydrodynamic cavitation (HC) has emerged as a promising technique for process intensification. Recently developed advanced rotational hydrodynamic reactors (ARHCRs) have attracted significant attention from both academia and industry due to their notable economic advantages, high processing capacity, continuous operation in specific applications. However, existing evaluation optimization criteria these primarily rely on external parameters, often overlooking the complex micro-scale properties energy dissipation of internal flow within generation unit (CGU) ARHCRs. To address this, "simplified field" computational dynamics (CFD) approach combined with entropy production theory was employed assess impact protrusion installation upstream CGU ARHCR performance. The volume total were analyzed protrusions various shapes, circumferential offset angles (γ), radial positions (r), side lengths (s). findings revealed that ARHCRs is predominantly localized regions separation vortex formation CGU. Furthermore, an multiple design factors identified triangular γ 3.75°, r 122.5 mm, s 1 mm achieved optimal Comparative analysis field structures between baseline model demonstrated modifies downstream dynamics, stabilizes clearance field, reduces production. Additionally, modifications expand low-pressure region, thereby enhancing In this study, spatial distribution loss dominant pathways ARHCR, revealing underlying mechanism associated separation. These insights contribute deeper understanding efficiency offer foundation optimizing reactor minimize consumption enhance

Language: Английский

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Corrosion of welding reinforcement height under dynamic conditions

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(3)

Published: March 1, 2024

The presence of welding reinforcement height (WRH) within oil and gas pipelines can lead to micro-turbulence in localized areas during transportation, resulting corrosion failure. This study employed a modular reconstruction method simulate reconstruct X80 steel welded joints, investigated the erosion-corrosion behavior at WRH using wire beam microelectrode, electrochemical impedance spectroscopy, computational fluid dynamics simulations. results show that galvanic current density (GCD) weld metal exhibits cathodic behavior, while GCD base heat-affected zone shows anodic behavior. top is susceptible As radius increases, rate also increases. Additionally, increases similarly with an increase flow velocity. intensity factor (g) 0.24, local moderate. work has scientific significance ensuring long-term safe operation reducing risk

Language: Английский

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Entropy transport for quasi-one-dimensional flow

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(7)

Published: July 1, 2024

The study of entropy in the context quasi-one-dimensional flow is expanded this work. Specifically, a new transport equation derived and integrated into closed-form algebraic expression for change. derivation identifies respective components change valid flows with an arbitrary combination area change, heat transfer, friction. irreversibility identified found to be composed frictional dissipation, irreversible work term that results from restriction flows. each component first validated using several canonical (i.e., isentropic, Fanno, Rayleigh, normal shock). A unique production mechanism producing (e.g., Two additional cases, sudden expansion contraction, are then considered show sole mechanism. Finally, simultaneous friction transfer examined, overall decomposed contributions dissipation terms. In all net newly expressions agrees known solutions within numerical precision.

Language: Английский

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Research on a new pressure pulsator

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(9)

Published: Sept. 1, 2024

Pulsators are widely used to study the dynamic characteristics of liquid flow components. However, it is difficult adapt existing actuators excitation requirements under high pressures, low temperatures, and toxic media. This describes design a novel pressure pulsation device presents results simulations experimental tests. The field simulated series working conditions, effects rotation speed, rate, inlet pressure, gap between rotor stator on peak-to-peak amplitude, spectral resistance coefficient actuator outlet analyzed. A prediction model for corresponding parameters developed using multiple linear regression. In high-pressure (20 MPa) hydraulic pipeline tests, can generate pulsating with amplitudes more than 7 MPa in time domain 2 frequency domain. upstream downstream regions internal periodically joined detached by blade rotation, which periodic variations velocity pressure. relative error predictions three-dimensional simulation values less 7%, satisfying industrial requirements. work facilitates solution problem when analyzing response fluid equipment pipelines provides method forecasting output effects.

Language: Английский

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