Flow Regime Research Articles

Assessment of MARS-KS prediction capability for natural circulation flow in passive heat removal system

Considering that system analysis codes are used for the evaluation of the performance of Passive Safety Systems (PSSs), it is important to investigate the capability of the system analysis code to reliably predict the heat transfer and natural circulation flow, which are the main phenomena governing the performance of a PSS. Since MARS-KS has been widely validated for heat transfer models, this study focuses on evaluating its capability to predict the single and two-phase pressure drops and natural circulation flow. The straight pipe simulation results indicate that the pressure drop predictions are reliable within ±5 % error margin for the single-phase flow and the errors of pressure drop up to −30 % for the two-phase flow. Through single-phase natural circulation flow analysis, it is concluded that the use of the appropriate K-factor modeling based on the flow regimes is important since the natural circulation flow rate in MARS-KS is mainly affected by the form loss factor modeling. With two-phase natural circulation flow analysis, this study emphasizes the behavior of the system could change significantly depending on the two-phase wall friction and pressure loss modeling. With the analysis results, modeling considerations for the PSS performance evaluation with the system analysis codes are proposed.

Bed structure of CNT agglomerates in gas–solid fluidized beds

In this study, the bed structure according to the flow regime of fine particles in gas–solid fluidized beds was studied by measuring the pressure drop and heat transfer coefficient. Two types of carbon nanotube (CNT) agglomerates with behavior similar to Geldart A and Geldart B and two types of glass bead (GB) particles corresponding to Geldart A and Geldart B classification were used. CNTs fluidized in the form of agglomerates, and in some CNT agglomerates, a homogeneous expansion regime with suppressed generation of bubbles, were observed. In the homogeneous expansion regime of CNT agglomerates, the relationship between superficial velocity and voidage was consistent with the Richardson–Zaki equation, and had a higher n value than that of Geldart A particles and fumed silica agglomerates. In this regime, small-diameter channels coexisted, and due to unstable fluidization at low superficial velocity, intermittent bed collapse occurred. In the homogeneous expansion regime of GB particles, the heat transfer coefficient remained constant, and as bubbles were generated, the heat transfer coefficient increased. On the other hand, as the superficial velocity increased, the heat transfer coefficient of CNT agglomerates continuously increased, regardless of the flow regime transition. In the homogeneous expansion regime of CNT agglomerates, unlike Geldart A particles, movement of agglomerates within the bed was confirmed, and a dynamic bed structure was present, in which the movement increased according to the superficial velocity.

Extension of finite particle method simulating thermal-viscoelastic flow and fluid–rigid body interactional process in weakly compressible smoothed particle hydrodynamics scheme

In computational non-Newtonian fluid dynamics, heat transfer has obvious effects on motions of viscoelastic fluids, mechanical mechanism of elasticity, and flow regimes. This study suggests an extended numerical scheme of smoothed particle hydrodynamics and finite particle method within density smoothing (SPH_DSFPM), which involves the discretization of smoothed particle hydrodynamics (SPH) and finite particle method (FPM) within density smoothing (DS) in the weakly compressible flow scheme. A corrected particle shifting technique is incorporated to eliminate tensile instability and inhomogeneity near solid boundaries. A corrected dynamic solid coupled boundary is introduced to deal with casting molding within high-pressure operations, which has a good compatibility between virtual particle method and repulsive force model. Numerical results show that the present scheme has the nearly lower relative error (0.5%) than conventional SPH (2.6%) in the case of evolutionary thermal-viscoelastic Poiseuille flow and heat effects have active influences on velocity, pressure variations for viscoelastic fluid flow around periodic circular cylinders. Three different printing modes of moving printers significantly generate into differentiated forming regimes through high-pressure extrusion. Adaptive particle distributions possess robust flow evolutions, by which the shocked jets can be tracked well and the sinking velocities of wedge entering into solutions can be numerically probed well considering different cuspidal biting angles. In the case of macroscopic fluid–rigid body interactions, the statistical degree of deviation on probed forces with experiments is relatively 4.35% and that is 12.5% for SPH. The proposed numerical scheme has a good performance on improved accuracy, convergence, and stability for simulating transient thermal-viscoelastic flows.

Multiple hot spot cooling with flow boiling of HFE-7000 in a multichannel pin fin heat sink

Electronics cooling applications require a high cooling performance due to increasing power consumption. Phase change heat transfer is a popular approach for offering high heat flux cooling. Controlling temperature distribution and mitigating boiling instabilities under high heat flux conditions present a significant challenge. While numerous studies investigated the effect of pin fins in a minichannel with single hotspots on boiling enhancement, few research studies are available for minichannels with multiple segmented hotspots. This study's primary objective is to dissipate high heat (1.4 kW) using flow boiling of a dielectric fluid, namely HFE-7000, which has lower thermophysical properties than water, to achieve a uniform temperature distribution, and to suppress boiling instabilities. The boiling performance of a pin fin multichannel heat sink with dimensions of 3 × 14 × 300 mm (H × W × L) subjected to 8 hotspots with uniform heating was investigated in this regard. Flow boiling experiments were performed over a wide range of input heat power from ∼0.1 to ∼1.4 kW with a coolant mass flux of 500 kg/m2 s in the three parallel minichannels having staggered elliptical pin fins with no tip clearance on each hotspot and distribution pins at the inlet. High-speed visualization was used to relate the heat transfer coefficient variations along the channel to flow patterns. The heat transfer performance and flow regimes at different locations were obtained and discussed. Thanks to the mixing effect of elliptical micro pin fins with optimum geometrical parameters along the heat sink, the presence of distribution pin fins at the inlet for suppressing boiling instabilities and early transition to stable annular flow, the temperature uniformity (∼2.3 °C, temperature difference between the inlet and outlet hotspots) could be achieved at the highest heat input. Heat transfer coefficient reduction upto 27 % was reported along the channel when comparing inlet (1st) and outlet (8th) hotspots.

A three-dimensional numerical well-test model for pressure transient analysis in fractured horizontal wells with secondary fractures

During oil and gas reservoir development, multi-stage horizontal wells (MFHWs) and hydraulic fracturing techniques can effectively increase estimated ultimate recovery. However, there still lacks an understanding of the three-dimensional (3D) pressure transient behaviors of multi-stage fractured horizontal wells with secondary fractures. To narrow this gap, a three-dimensional numerical well-test model based on a discrete fracture model and unstructured tetrahedral grids is developed to study the pressure transient behaviors of MFHWs with secondary fractures. The pressure transient solutions of MFHWs with secondary fractures have been demonstrated by model verifications. The results show that the proposed model can accurately capture the complex transient flow around fractures, including early radial flow that is not easily captured by two-dimensional numerical well test models. The proposed model classifies the flow regimes of a MFHW as: wellbore storage and skin effects, early radial flow, bilinear flow, linear flow, elliptical flow, pseudo radial flow, and pseudo-boundary dominated flow. It is found that the fracture geometry has a relatively large effect on the shape of the pressure derivative curve in this work. The hydraulic fracture half-length has the greatest impact on the pressure transient behaviors of the MFHW, followed by fracture height and secondary fracture half-length, as found in this study. Additionally, fracture parameters are evaluated, and actual well testing data are interpreted, taking into account the fracture height. This work is meaningful to understand the three-dimensional pressure transient behaviors of MFHWs with secondary fractures.

Design of closed loop for reproduction of gas-dominated hydrate flow.

The study presents a novel setup for measuring the flow regime of hydrate particles in a gas-dominated flow, which is of interest for applications such as natural gas transportation. A closed-flow loop, driven by a novel internal fan, enables continuous observation of hydrate particle behavior in a gas flow. The experimental setup allows the production and insertion of HFC134a gas hydrate particles with diameters of 10-50μm into the gas flow loop via a bypass loop. The performance curve of the internal fan is validated, and its suitability for achieving the required flow speed (5m/s) is demonstrated. Through an observation window using camera systems, the flow regime of glass beads is successfully visualized and analyzed. To validate the experimental data, a coupled computational fluid dynamics-discrete element method model is used to simulate the particle flow density distribution. The study findings demonstrate the effectiveness of the experimental setup in characterizing the flow regime of hydrate particles in a gas-dominated flow.

Optimization Method for Fracture-Network Design under Transient and Pseudosteady Conditions Using Unified-Fracture-Design and Deep-Learning Approaches

Summary In unconventional shale and tight reservoirs, the concept of stimulated reservoir volume (SRV) is used to correlate the volume of total injected proppant with well performance. The SRV configuration consists of primary fractures connected to the wellbore and secondary fractures intersecting primary fractures. SRV productivity is determined by fracture conductivity, fracture dimensions, and network complexity, which also vary with time. This work presents an extension of the unified-fracture-design (UFD) approach to account for not only the pseudosteady state (PSS) but also transient flow regimes and ultimately optimize SRV for maximizing well performance. A generalized productivity index (PI) for both the transient and PSS regimes is presented to improve well performance by searching for the maximum PI over time. In addition, a surrogate model is developed to accelerate the optimization. This study demonstrates that the UFD enables the determination of the optimal fracture network conductivity and complexity that contribute to the maximum PI with a given proppant volume. The optimal SRV design is time-dependent until the PSS is reached. The surrogate model not only improves the computational efficiency but also delivers high precision, which means far less computational burden than the traditional parametric-sensitivity analysis.

Single-Well Simulation for Horizontal Wells in Fractured Gas Condensate Reservoirs.

Fractured gas condensate reservoirs (FGCR) are a complex, special, and highly valuable type of gas reservoir, accounting for a significant proportion of gas reservoir development. In recent years, with the continuous advancement of horizontal well technology, it has become the main approach for the development of FGCR. The current model is unable to accurately represent the fluid distribution in the near-well area of horizontal wells due to the unique retrograde condensation phenomenon in GCR. Additionally, the presence of fractures complicates the solution of traditional analytical models. In response to this issue, this paper proposes a novel semianalytical model for horizontal wells in FGCR, which incorporates natural fractures, multiphase flow, and the influence of stress sensitivity on pressure response. A dual-porosity model is employed to simulate fractured reservoirs, and a four-region radial composite model is developed to characterize multiphase flow resulting from retrograde condensation in GCR. The pseudopressure transform, Pedrosa transform, Laplace transform, and Finite Cosine transform are utilized to address the nonlinear partial differential equation. A systematic verification of the semianalytical solution is confirmed through a comparison with the numerical solution from computer modeling group (CMG). We thoroughly explain the physical significance of the various features by identifying the 12 flow regimes of the typical curve. Furthermore, we offer a method for assessing the extent of retrograde condensation and the size of the retrograde condensate region based on the curve's characteristics. Finally, the pressure measurements recorded from the Bohai field are carried out to validate the accuracy of the proposed model. The results show that the predictions of the new model are in good agreement with the actual production data, demonstrating the proposed solution's applicability.

Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling

AbstractAccurate simulation of reservoirs has been a challenge for global hydrological models due to highly discontinuous water management and uncertainties in reservoir shape representation. In addition, at a global scale, it is crucial to consider those reservoirs that disrupt the downstream flow regime. We augment the mesoscale Hydrological Model with a newly developed lake module (LM) that incorporates an existing reservoir regulation scheme with non‐consumptive demand predictions from random forest. We also evaluate the sensitivity of reservoir shape on streamflow and evaporation for three shape approximations of varying complexities. We tested the LM across 31 non‐consumptive reservoirs covering an extensive range of hydroclimatic characteristics and demonstrate the applicability by using freely available global reservoir information. Streamflow simulations with reservoirs and model calibration show a median Kling‐Gupta Efficiency improvement of +0.94 (calibration) and +0.77 (validation) when compared against model simulations without reservoirs and default parameter set. We find reservoir evaporation highly sensitive to reservoir shape with half‐pyramid approximation consistently resulting in best fit at reservoirs with surveyed bathymetry. In contrast, the linear approximation (rectangular prism) produced a median bias of +114% relative to half‐pyramid, for estimating evaporation, across all the reservoirs. Streamflow simulations were insensitive to the reservoir shape. Our analysis shows that 30% of the non‐consumptive hydropower reservoirs of the GRanD data set are non‐disruptive and can be excluded without loss to model realism. Further work is necessary for testing the regulation approach in reservoirs with consumptive water usage.

Perennial and Non‐Perennial Streamflow Regime Shifts Across California, USA

AbstractDespite rises in drought frequency and human water demands, streamflow regime shifts from perennial to non‐perennial have not been evaluated in many arid/semi‐arid regions. To document shifts, we created a methodology that classifies streams as naturally perennial or non‐perennial. Our classification used historical, minimally disturbed‐quality USGS streamflow gages (1950–2015) across California. The number of consecutive zero flow days (≥5 days) was used to classify 61% (96/158) and 39% (62/158) of gages as perennial and non‐perennial, respectively. We developed a random forest model to predict flow regime class based on climate and watershed characteristics. To identify regime shifts, we compared the observed class of contemporary (1980–2023) minimally disturbed and disturbed gages with their modeled, natural class. For most minimally disturbed gages, the observed and natural predicted classes were the same, but 13% (7/52) of gages had a modeled perennial regime with an observed non‐perennial class, indicating a drying trend. Among disturbed gages, 22% (64/290) shifted from perennial to non‐perennial and 7% (21/290) from non‐perennial to perennial. Trends in the minimum 7‐day moving average and number of zero‐flow days provided further evidence of drying at minimally disturbed streams, but no pattern at disturbed gages. Our results indicate that few minimally disturbed perennial streams have become non‐perennial to date, but many streams have experienced drying from climate. Streams impacted by human activities had greater drying rates, but regulation has caused some non‐perennial streams to become perennial. By quantifying expected natural streamflow regimes, this work can help monitor, manage, and conserve stream ecosystems.

Flood Mapping Using HEC-RAS and HEC-HMS: A Case Study of Upper Citarum River at Dayeuhkolot District, Bandung Regency, West Java

Dayeuhkolot district is an area within Citarum River watershed that often experiences flood during the rainy season due to overflow discharge. This research identifies the flood area by using hydrodynamic modeling in Dayeuhkolot district. The model utilized satellite rainfall data. The hydrodynamic modeling of HEC-RAS 5.0.5 and HEC-HMS simulate the flow regimes and the hydrological characteristics in the study area, respectively. The results reveal that the increase in water level in two river tributaries within Citarum River watershed had caused the flooding at Dayeuhkolot district. Furthermore, the percentage of flood areas with low, medium, and high flood risk is 34.7%, 34.5%, and 30.8%, respectively. The flood map developed in this study could support the establishment of a strategy for managing the floodplain area and flood-affected areas.

Microchannel-based Droplet Generation Using Multiphase Flow: A Review

Microfluidics is a multidisciplinary field that allows for precise control of fluids at a micrometer scale, with the goal of generating encapsulated structures or droplets for specific purposes. However, producing monodispersed droplets remains a challenge, making it necessary for researchers to investigate optimal microchannel geometries and parameters for controlling droplet size. Channel-based geometries, including T-junction, flow-focusing, co-flowing, membrane, and step emulsification, are the most commonly used geometries, each with its own advantages and weaknesses. This literature review aims to highlight assessment methods of microfluidic device performance and physical phenomenon in droplet generation for each channel-based geometry, including recent findings by researchers. Output parameters such as microchannel geometries, flow patterns, and flow regime maps with interpretations can be used to evaluate the optimum input for generating droplets that are suitable for a certain application. With the COVID-19 pandemic affecting the world, there is an opportunity to use microfluidic devices to study SARS-CoV-2 and develop post-pandemic therapeutics. The next challenge in microfluidic device development is producing high-throughput double emulsion droplets with monodispersed size using optimum input parameters to satisfy the drug delivery purpose.

Memory and scission effects of polymers on the flow regime of polyethylene oxide solutions in continuous abrupt contraction–expansion microchannels with different cavity lengths

Memory and scission effects of polymers on the flow regime of polyethylene oxide solutions in continuous abrupt contraction–expansion microchannels with different cavity lengths

The effect of viscosity on the self-similar growth of conic cusps on the surface of a conducting liquid in an electric field: Limiting cone angle

The dynamics of the formation of conic cusps on an initially smooth surface of a perfectly conducting liquid (liquid metal) in an external electric field is analytically studied. When the singularity is formed, the apex curvature radius of the accelerating protrusion, local electric field strength, and fluid velocity become infinite in a finite time. It has been demonstrated that two scales with different types of fluid behavior can be distinguished in this process. At the nanoscale (the curvature radius of the conic apex is tens of nanometers or less; the electric field strength at the apex is about 108 V/cm and higher), viscous effects play a decisive role, and a cone with the limiting opening angle of 33.1° is formed. On the macroscopic scale (the local field strength is less than 108 V/cm for liquid metals), the ideal fluid approximation is applicable, and a cone of the opening angle 98.6° (Taylor's angle) develops. In both cases, self-similar fluid flow regimes are realized, for which the spatial scale decreases with time following the power law (t0 – t)2/3, where t0 is the blowup time. In this process, the Weber number remains practically unchanged and, according to our estimates, approximately equal to 102; at the same time, the Reynolds number decreases as (t0 – t)1/3.

Study on flow characteristics and phase holdup in a slurry bubble column coupled with mild agitation

A pilot-scale experimental setup was constructed to investigate the effect of mild agitation on the bubble characteristics and phase holdup in a slurry bubble column. Mild agitation positively impacts the axial uniform distribution of solid holdup, though it shows insignificant influence on the radial distribution. In homogenous regime, mild agitation promotes the coalescence of bubbles, and the effect becomes stronger with increasing agitator speed. The mild agitation contributes to a decrease in bubble size in heterogeneous flow regime. Mild agitation presents a significant effect on the gas holdup by adjusting the bubble size and bubble motion trajectory. The modification was introduced to predict the gas holdup considering the effects of mild agitation, a necessary consideration for applications requiring mild agitation. This adapted model predicts gas holdup with a maximum error of 12.9%.

A deep learning approach to classifying flow-induced vibration response regimes of an elliptical cylinder

This study proposes a new approach that leverages deep learning to the study of flow-induced vibration (FIV), specifically to automate flow regime classification and to visualize the transitions between these regimes. Using previously obtained data on the amplitude response of an elastically mounted cylinder as a function of reduced velocity for a range of structural damping ratios, the time trace of the body displacement and fluid driving forces are first converted into a frequency-time representation using continuous wavelet transforms before being input to several pre-trained convolutional neural networks for feature extraction. When utilizing the outputs of each convolutional neural network for regime classification, we found that almost all the machine learning approaches had high cross-validation accuracy that was statistically insignificant from each other. The five best-performing classifiers were then used as an ensemble method, yielding a weighted accuracy of 99.1% on the test data. The FIV response regimes were further investigated by projecting the outputs of the pre-trained convolutional neural networks onto the first three modes identified with principal component analysis (PCA). The PCA plots indicated that, among all the models considered, Xception showed superior capability in delineating distinct locations for different FIV response regimes, based on the lock-in frequency and the presence of harmonics in the driving fluid forces. Moreover, the PCA plots also showed that increasing the structural damping ratio resulted in a diminished disparity in the dynamics of the identified FIV response regimes, leading to a less discernible separation between the regimes in the plots.

Inferring Tracer Diffusivity From Coherent Mesoscale Eddies

AbstractMixing along isopycnals plays an important role in the transport and uptake of oceanic tracers. Isopycnal mixing is commonly quantified by a tracer diffusivity. Previous studies have estimated the tracer diffusivity using the rate of dispersion of surface drifters, subsurface floats, or numerical particles advected by satellite‐derived velocity fields. This study shows that the diffusivity can be more efficiently estimated from the dispersion of coherent mesoscale eddies. Coherent eddies are identified and tracked as the persistent sea surface height extrema in both a two‐layer quasigeostrophic (QG) model and an idealized primitive equation (PE) model. The Lagrangian diffusivity is estimated using the tracks of these coherent eddies and compared to the diagnosed Eulerian diffusivity. It is found that the meridional coherent eddy diffusivity approaches a stable value within about 20–40 days in both models. In the QG model, the coherent eddy diffusivity is a good approximation to the upper‐layer tracer diffusivity in a broad range of flow regimes, except for small values of bottom friction or planetary vorticity gradient, where the motions of same‐sign eddies are correlated over long distances. In the PE model, the tracer diffusivity has a complicated vertical structure and the coherent eddy diffusivity is correlated with the tracer diffusivity at the e‐folding depth of the energy‐containing eddies where the intrinsic speed of the coherent eddies matches the rms eddy velocity. These results suggest that the oceanic tracer diffusivity at depth can be estimated from the movements of coherent mesoscale eddies, which are routinely tracked from satellite observations.

Modeling analysis of pulsatile non-Newtonian blood flow in a renal bifurcated artery with stenosis

A transient transport flow model is adopted in a renal bifurcated artery with different stenosis cases to examine the flow phenomena when the non-Newtonian blood flow regime within the three-dimensional space domain is chosen as a pulsatile nature. The nonlinear governing equations are solved using the Finite Element Method with suitable initial-boundary conditions. During numerical computation, distinct hemodynamic parameters including Wall shear stress, Reynolds number, power law index are evaluated based on different stenosis severities (0%, 25%, and 50%) and stenosis lengths (0mm, 0.5mm, and 1mm). For 0%, 25%, and 50% stenosis, the approximate values of velocity and pressure profiles are estimated at t = 5s at various positions, and achieved the highest velocities that were around 0.07m/s, 0.08m/s, and 0.13m/s respectively. The unsteady response of the stress due to stenosis-induced shear on the outside wall is described as a result of stenosis at t = 0.1s, 0.2s, 5s. The flow is severely restricted by constriction, which increases wall movement and produces stress, depending on the amount of stenosis. As pulsatile flow time increases due to the presence of stenosis, the wall shear stress decreases gradually. The impact of Reynolds numbers on pressure profiles and velocity profiles are displayed for Re = 100, 300, 500, and 700, and found that both velocity and pressure outlines increase significantly. In order to identify the flow phenomena, the influences of the power law index for n = 0.1, 0.3568, 0.5 are presented on the velocity and pressure profiles. Shear-thinning flow occurs for 0<n<1, pseudoplastic flow occurs for n = 0.1 and Bingham plastic flow occurs for n = 0.5. The modeling investigations of blood flow via arteries could assist in the diagnosis and treatment of arterial illnesses; as well as expand the knowledge about cardiovascular physiology and lead the development of revolutionary medical interventions to enhance patient treatment outcomes.

Научно-технологические основы разработки месторождений подземных вод с принудительным самоизливом

Introduction. A two-well borehole system is proposed, providing for the extraction of groundwater by forced self-discharge. The essence is to create conditions for the emergence of a down hole energy source in the form of hydraulic shocks, alternating hydraulic impulses affecting aquifers and ensuring the rise of water to a height. Materials and methods of research. A block diagram of a two-well circulation system of wells consisting of an above-ground tank, an injection well with a ledge, a water-lifting well connected by an intermediate trunk. The objects of the study are the shape of the above–ground tank, its connection with the injection well, the location of the ledge and the conditions for conducting a water circulation channel from the ledge to the above-ground tank. Methods – calculation of the energy characteristics of a two-well system, experiments to study the mechanism of the origin of incomplete hydraulic shock, boundary values of the modes of water movement in the system and the coefficient of injection of rocks. They were carried out on the installation with the possibility of visual observation of the processes taking place in the system. Results. When an incomplete hydraulic shock occurs on the ledge of the injection well, the flow is divided into core and lateral components. The water flow from the tank into the well was in the range of 20–60 l/min. The origin of incomplete hydraulic shock occurred at a water flow rate of 20 l/min, with an increase in pressure up to 7.0 atmospheres. The boundary values of the laminar flow mode of water flow are 60 l/min. The height of the water rise (H) mainly depends on the depth of origin of incomplete hydraulic shock (H1). The ejection coefficient of rocks decreases with increasing flow rate of the working flow. Discussion. The results of the study are due to the design features of the elements of the two-well circulation system of wells. The operating conditions of the system are the type of communication ground tank – injection well – aquifer, the location of the ledge, the execution of the water circulation channel from the ledge to the entrance to the ground tank with one diameter, the preservation of the laminar flow regime of water, the exclusion of pressure loss and water leakage in the intermediate trunk. Conclusions. The conditions for the origin of a down hole energy source in the form of renewable hydraulic shocks, which have a hydro impulsive effect on aquifers, have been established. A block diagram of the injection and circulation system of wells for the extraction of groundwater by forced self-discharge has been formed. Resume. The validity of the idea of injection-forced self-discharge of groundwater is proved by the results of research. The results are applicable in the development of groundwater with low-pressure and non-pressure aquifers. The objects of future research are the optimal ratios of the diameter of the injection well and the passage section of the ledge, the expansion of the boundary values of the flow transition from laminar to turbulent motion, and an increase in the ejection coefficient.

Influence of Partition Wall Length on Inlet Flow Regime of a Pumping Station Arranged in Parallel with a Sluice Gate

When a sluice gate is arranged in parallel with pumping station units, biased flow occurs in the forebay when the units are operating. The transverse flow velocity in front of the channel inlet is relatively high, and, in severe cases, it may lead to the formation of suction vortices, impacting the stable operation of pump units. Taking the Liushan Pumping Station project of the Eastern Route of the South-to-North Water Diversion Project as a case study, this paper investigates the effect of the partition wall length on the inlet flow regime of pumping station units arranged in parallel with the sluice gate to reduce the transverse flow velocity in front of the channel inlet. Using numerical simulations, the inlet flow regimes for different partition wall lengths were compared. Moreover, the flow field distributions in the forebay under different operating conditions were analyzed alongside the transverse flow velocity in front of the channel inlet and the uniformity of flow velocity distribution in the section behind the channel inlet. Hydraulic model tests were then conducted to validate the simulation results. The results indicate that in the original design, there existed a vortex zone in the forebay in front of the inlet of the channel where the transverse flow was relatively high. However, the introduction of partition walls significantly reduced the transverse flow velocity in front of the inlet of the channel in the forebay. The optimal effect was achieved when the length of the partition wall was twice the width of the inlet channel. Furthermore, the uniformity of velocity distribution at the inlet of the channel increased by an average of 7.4%, leading to a substantial improvement in the inlet flow regime of the pumping station. The addition of partition walls in the forebay effectively resolved the issues related to the flow regime in the forebay, providing valuable references for similar engineering studies in the future.