Jul 2026· ISH Journal of Hydraulic Engineering· Vol 32, pp. 776 - 792· 0 citations· 8 references
Abstract
ABSTRACT A three-dimensional CFD (Computational Fluid Dynamics) study was performed to evaluate the hydraulic performance of an existing flood‑protection pump sump designed for a discharge of 16.48 m3/s. The study aimed to assess flow uniformity at bell-mouth suction, quantify swirl angles, and identify subsurface vortex formation under operating conditions. A novel trident-shaped splitter combined with dividing walls is proposed to mitigate vortex-induced instabilities. The Reynolds-Averaged Navier–Stokes (RANS) equations combined with the realizable k–ε turbulence model and VOF (Volume of Fluid) approach were solved using STAR-CCM+. Results indicate that vortex intensity and flow separation observed in the original design are significantly reduced with the proposed modifications. Quantitative analysis shows swirl angles below 1.6°, well within Hydraulic Institute limits (5°). Mesh‑independence and pressure‑distribution analysis confirm improved hydraulic stability and reduced risk of mechanical damage.
This study presents a computationally efficient quasi-one-dimensional mathematical model based on the traveling wave method to investigate hydraulic shock attenuation using a gas-hydraulic damper in pipeline systems. Unlike conventional models, this formulation accounts for fluid compressibility and incorporates a non-linear boundary condition strictly satisfying gas mass conservation within the damper. The model was successfully validated against a MATLAB 2024 Simulink benchmark, demonstrating a maximum pressure amplitude discrepancy of only 5–8%. A parametric analysis evaluated the effects of damper volume, initial gas pressure, and pipe diameter on surge suppression. Results show that insufficient damper volume causes extreme negative pressure drops, risking severe cavitation and fluid column separation. Conversely, excessive volume induces “over-damping,” undesirably increasing system inertia and delaying steady-state recovery. Crucially, scaling analysis reveals that a damper optimized for a specific pipe diameter loses efficacy in larger pipes, as the flow’s kinetic energy scales with the diameter’s square. This model provides a robust, precise computational tool for the optimal and safe design of pipeline networks.
B. Bakhtiyorov, K. Mamadaliev, Khayotjon Aminov et al.· Fluids· 0 citations
This study presents a Computational Fluid Dynamics (CFD) analysis of fluid flow in tank farm
pipelines, with emphasis on friction factor and pressure drop characteristics. The hydraulic
performance of the pipeline system was evaluated, and CFD predictions were validated using
empirical correlations. A three-dimensional pipeline model was developed and simulated in
ANSYS Fluent under turbulent flow conditions. The results indicate that pressure drop increases
significantly with increasing flow velocity and pipe length, while the friction factor decreases
slightly with increasing Reynolds number. At a flow velocity of 20 m/s, a pressure drop of
approximately 15 kPa was recorded, accompanied by a drag force of 0.024 kN. Furthermore, the
CFD predictions showed good agreement with the Colebrook White correlation, with an average
deviation of less than 5%. The findings demonstrate that CFD is an effective tool for predicting
energy losses in tank farm pipeline systems and can support operational optimization, pipeline
design, and flow assurance analysis.
Okokon Reagan Ekpenyong· International Journal of Eng...· 0 citations
This study addresses the need to improve the performance of split-type reaction water turbines (SRWTs) for low-head hydropower applications, where hydraulic losses and flow instability often limit torque output and efficiency. The objective was to optimize a modified SRWT by evaluating the effects of nozzle-edge sharpening angle, guide-pipe length, and guide-pipe diameter on torque and hydraulic efficiency. A CFD-based optimization framework was developed by integrating ANSYS Fluent simulations with Response Surface Methodology using a three-factor, three-level Box–Behnken Design. Fifteen design cases were simulated, and reduced quadratic models were established for torque and hydraulic efficiency, while pressure drop was analyzed as a supporting hydraulic indicator. Results showed that the sharpened nozzle angle had the strongest influence on both responses. The optimum design, consisting of a 52.02 mm guide-pipe length, 112.49 mm guide-pipe diameter, and 64.99° nozzle angle, produced a predicted torque of 31.22 Nꞏm and hydraulic efficiency of 85.31%, which were closely confirmed by CFD. Compared with the baseline design, the optimized turbine improved torque by 41.42% and hydraulic efficiency by 41.44%. These findings demonstrate that CFD coupled with RSM is an effective tool for optimizing SRWT geometry for low-head hydropower applications.
Murshied Aloyod, J. Honra· E3S Web of Conferences· 0 citations
The Wells turbine is a key component in an Oscillating Water Column (OWC)-based ocean wave energy conversion system, yet its limited operating range due to leading-edge stall constrains overall system efficiency. This study presents an independent CFD benchmark of the performance of the Wells turbine with and without a passive flow control device, a stall fence, as investigated by Das and Samad (2020). Steady Reynolds-Averaged Navier-Stokes (RANS) simulations using the SST k-ω turbulence model were performed in ANSYS CFX v22.1 by replicating the original geometry, boundary conditions, and mesh density for direct comparison. The reference turbine (eight NACA 0015 blades, solidity 0.64) and the configuration with a stall fence (fences at 40% and 80% span) were evaluated over a flow coefficient range of φ = 0.075-0.275. Grid independence study using quantitative (non-dimensional torque T*) and qualitative (tip-vortex topology) criteria resulted in the selection of a 3.5-million-element mesh. For the reference turbine, a mean absolute percentage error (MAPE) of 2.0% for T* and 3.1% for efficiency was obtained in the pre-stall range (φ ≤ 0.225), confirming strong numerical reproducibility. However, steady RANS failed to predict the stall onset for the reference configurations and overpredicted torque by up to 508% in the post-stall region. The stall point at φ = 0.250 was successfully reproduced with a deviation approaching zero, proving that the vorticity induced by the fence geometry enhances the reliability of RANS stall predictions. The pre-stall MAPE for the fence configuration was 4.4% for T*, slightly higher due to local vortex interactions around the fence. These findings establish steady RANS as a reliable design tool in the pre-stall range and demonstrate that passive fence stalls not only extend the turbine’s operating range but also improve the accuracy of CFD predictions. Keywords: Wells turbine, Stall fence, CFD benchmark, Steady RANS, Ocean wave energy conversion.
Muhammad Nurfajriansyah Muslich, A. Prabowo, R. Adiputra et al.· Research in Education, Techn...· 0 citations
Hydraulic short-circuit (HSC) operation is an important approach to enhancing the operational flexibility of pumped-storage power plants (PSPPs). However, under this new operating mode, the flow characteristics in the bifurcated pipe deteriorate significantly, posing a threat to the efficiency of the piping system and potentially affecting the inflow conditions for the turbine. In this study, six improved bifurcated pipe models were designed, and their internal flows under pumping, generating, and HSC modes were numerically simulated. Entropy production theory and vortex identification method were employed for flow field analysis. The results show that local modifications confined to the bifurcation are insufficient to simultaneously improve energy characteristics across different modes. In contrast, the bypass pipe enables early flow diversion, weakening the original high-dissipation regions while introducing controllable additional losses. M6 achieves an average energy loss reduction of 47.85% in the mid-to-high flow split ratio range (FSR > 0.3). A strong correlation is observed between vortex suppression and energy loss reduction: the bypass pipe substantially shortens the main vortex length at the inlet section of the generating branch, while simultaneously inducing new shear vortices at the junction; adjustment of its installation position is expected to further shorten their extension, thereby ensuring the normal operation of the turbine. This study provides a new technical pathway for extending the operating range of HSC operation and contributes to enhancing the grid-regulation capability of PSPPs.
Shan Zhu, M. Xia, Shizhe Liu et al.· Machines· 0 citations
This study proposes a physics-guided optimization framework that integrates dimensional tolerance modeling, computational fluid dynamics, and Taguchi–Grey relational analysis to predict and improve the hydraulic performance of centrifugal pumps under realistic manufacturing variability. The framework establishes a quantitative link between geometric tolerances and flow-field evolution, thereby clarifying how clearance-induced deviations influence pressure redistribution, flow stability, and hydraulic energy transport. Four critical geometric tolerance parameters were evaluated using an L9 orthogonal array design. The numerical results identified an optimized blade-back clearance of 2.285 mm, corresponding to a hydraulic head of 19.588 m, an average flow velocity of 1.895 m/s, and a water horsepower of 1.824 kW. Analysis of variance further revealed that rear-shroud tolerance was the dominant factor governing pressure uniformity and hydraulic energy dissipation. Overall, the proposed framework provides a physics-based, tolerance-informed, and manufacturability-aware approach to hydraulic optimization by linking dimensional tolerance propagation, CFD-resolved flow behavior, and statistical performance ranking for clearance-sensitive pump design.
S. C. Tung, M. C. Lin, C. C. Huang· Journal of Applied Fluid Mec...· 0 citations
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