scholarly journals Numerical and Experimental Investigations of Flow Pattern and Anti-Vortex Measures of Forebay in a Multi-Unit Pumping Station

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 935
Author(s):  
Fan Yang ◽  
Yiqi Zhang ◽  
Chao Liu ◽  
Tieli Wang ◽  
Dongjin Jiang ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Pattern ◽  
Large Scale ◽  
Reduction Rate ◽  
Flow Speed ◽  
Experimental Investigations ◽  
Physical Model Test ◽  
Engineering Practice ◽  
Technical Problems ◽  
Pumping Station

The forebay of a pumping station is an important building connecting the diversion channel and the intake pool. Based on the physical model test and research method of computational fluid dynamics (CFD) based on the improved fluid volume model, the flow field in a forebay of a multi-unit pumping station is analyzed in combination with the engineering practice of the Exi River flood discharge station in the Anhui Province, China. Aiming at the technical problems of a large-scale swing water area in the forebay internal flow field of a lateral intake pumping station, the technical problems are discussed. Different rectification measures are selected to adjust the flow pattern in the forebay of a pumping station. The internal rectification flow pattern in the forebay under different plans, the uniformity of flow velocity distribution in the measurement section, and the reduction rate of the vortex area are studied and compared, and the optimal plan is given. The results show that the flow pattern of the 7.5 m and 15 m solutions of the lengthened inflow wall is still poor, and the ability to eliminate vortices is not strong or even counterproductive. The combination plan of a rectifier sill and a rectifier pier has a better effect and can eliminate more than 90% of the vortex, but the uniformity of flow speed has not been significantly improved at the inlet of the pumping station; the combination plan of a rectifier sill and a diversion wall opening has the best effect; the reduction rate of the vortex area is more than 85%, and the velocity uniformity of three measuring sections is better than that of the original plan. The uniformity of flow rate near the pumping station is increased by 4% and that far away from the pumping station is increased by 13%. The combination plan of a rectifier sill and diversion wall with openings is recommended.

scholarly journals Numerical simulation of hydraulic optimization for regulating tank in pumping station

2021 ◽  
Vol 880 (1) ◽  
pp. 012020
Author(s):  
Xiaoming Zhu ◽  
Sha Shi ◽  
Jing Si ◽  
Arniza Fitri ◽  
Dian Pratiwi ◽  
...  
Keyword(s):  
Flow Field ◽  
Side Wall ◽  
Engineering Practice ◽  
Governing Equations ◽  
Safe Operation ◽  
Pumping Station ◽  
Simplec Algorithm ◽  
Rng Turbulence Model ◽  
Wall Spacing ◽  
Good Agreement

Abstract Based on the governing equations of steady incompressible fluid, renormalization group (RNG) turbulence model and SIMPLEC algorithm are used to calculate the steady flow field of regulating tank in the pumping station with six different geometries operating under same condition. The impacts of the layout schemes of guide walls for the flow field of the regulating tank are analyzed. The numerical results are verified by physical model experiment and good agreement is found. The results show that: 1) serious flow separation of side wall will occur in the regulating tank when the interval of diversion wall is 10 L; 2) the flow velocity in the regulating tank will be too low when the diversion wall spacing is 16 L; 3) the improvement of the flow pattern of the regulating tank is not obvious; and the project cost is increased when the excavation depth of the regulating tank is increased by 1 m; 4) the bottom velocity reached the non-silting velocity and the head loss of the regulating tank reducing nearly 1.2 m by using arrangement form of wide 21 L and narrow 10L of the guide walls, which provides a certain guarantee for the safe operation of the pumping station. The regulation tank layout scheme proposed in the paper can be applied to engineering practice.

Investigations of the Boundary Layer on a Highly Loaded Compressor Cascade With Wake-Induced Transition

2006 ◽  
Author(s):  
Jens Iseler ◽  
Lothar Hilgenfeld ◽  
Michael Pfitzner
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Large Scale ◽  
Quality Data ◽  
Experimental Investigations ◽  
Generation Process ◽  
Unsteady Boundary Layer ◽  
Compressor Cascade ◽  
Boundary Layer Development ◽  
Layer Development

The flow field through a turbomachinery compressor cascades is significantly affected by the unsteady flow originating from the upstream blade rows. The interaction is caused by the wakes from the upstream blades, which affect the properties of the boundary layer of the downstream blades. In addition, pressure fluctuations exist between upstream and downstream blades. These phenomenona play a significant role in the loss generation process on turbomachinery blades because it influences the onset of transition in the boundary layer and has the potential to suppress a boundary layer separation in some cases. Extensive experimental investigations have been performed at the Institute of Jet Propulsion in Neubiberg, where these effects where studied in detail. The measurements were performed on a large scale compressor cascade called V103-220. The chord length of l = 220 mm chosen allowed the unsteady boundary layer development to be studied in great detail and provided high quality data for this complex flow, which can be used for the validation of CFD codes. Unsteady CFD calculations were performed using the RANS-code TRACE developed at DLR Cologne. A modern variant of the Wilcox k-ω turbulence model in combination with a newly implemented transition model was used, allowing a better determination of multimode transition. A multiblock grid with an O-type grid around the blade and a boundary layer resolution of y+<1 was used. Experimental and numerical results confirm that wake passing has a large influence on the unsteady boundary layer development also in this compressor flow case. The premature forced transition is followed by a stable calmed region, which partially suppresses laminar separation due to its higher shear stress level and delays the onset of transition in the path between wakes. In addition, it was found that the leakage from two slots, which are opened in the rig when the wake generator device is installed, changes the flow field considerably. This effect is not fully reproduced by the CFD calculations. To study this effect in more detail, three-dimensional steady and unsteady CFD calculations were undertaken and are being continued.

Improvement of Performance on Flow-Cutoff of Flap Valves Set in the Pressurized Tank of Pumping Station Based on Numerical Simulation

2013 ◽  
Vol 419 ◽  
pp. 86-90
Author(s):  
Yong Hai Yu ◽  
Bin Cheng
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Large Scale ◽  
Axial Flow ◽  
Free Water ◽  
Flow Distribution ◽  
Pumping Station ◽  
Simplec Algorithm ◽  
Distribution Uniformity ◽  
Free Plane

Two small flap valves arranged in parallel for each pump were used as flow-cutoff device in certain large-scale axial flow pumping station where the pressurized tank was designed as outlet structure. The flap valves of side-set pump had the poorest performance on flow-cutoff in the pumping station. The flow field in the pressurized tank was shown based on numerical simulation in order to improve the flow-cutoff performance of flap valves. The standard k-ε turbulence model and momentum equations were solved in the SIMPLEC algorithm with the assumption that the free water surface remained flat as a stress-free plane of symmetry. The velocity distribution and free outflow were prescribed on inlet and outlet boundary respectively. Numerical simulation on the flow field in pressurized tank was done at three typical moments chosen in the basis of the flow variation in the process of shutdown of flap valves. The reason that two flap valves of side-set pump could not close simultaneously and the late closing flap valve had a huge force on the wall was analyzed based on the comparison of flow field for side-set pump and middle-set pump. The result from numerical simulation proves that the division pier with appropriate size which helps to improve the flow distribution uniformity is valid for the two flap valves of side-set pump to close simultaneously.

scholarly journals Influence of Different Lateral Bending Angles on the Flow Pattern of Pumping Station Lateral Inflow

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jiren Zhou ◽  
Miaomiao Zhao ◽  
Chuan Wang ◽  
Zhenjun Gao
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Water Flow ◽  
Large Scale ◽  
Lateral Bending ◽  
Pumping Station ◽  
Lateral Inflow ◽  
Inlet Conditions ◽  
Backflow Zone ◽  
Bending Angles

A model of the pumping station lateral inflow forebay was established to explore the influence of different lateral bending angles of the pumping station lateral inflow. The lateral bending angles were set at 45° and 60°, and the two schemes were calculated separately. Analyzing the results of the numerical simulation showed that the flow patterns of the diversion passages of different schemes were good, but the advancing mainstream of the 1# inlet passage near the sidewall was seriously deviated after entering the forebay. Most of the water can flow smoothly into the inlet passage, while a small part of the water flowed into the sidewall and formed a backflow, resulting in a large-scale backflow zone near the left sidewall of the forebay. Moreover, the flow in the backflow zone was turbulent, which affected the water inlet conditions of the 1# water flow passage. Comparing the water inlet conditions of the water passage with the numerical simulation results of 45° and 60° bending angles showed that the larger the lateral bending angle of the forebay was, the worse the flow pattern of the water flow, and the more unfavorable the pump operation.

Numerical Simulation of the Unsteady Flow Field in an Axial Gas Turbine Rim Seal Configuration

2004 ◽  
Author(s):  
Ralf Jakoby ◽  
Thomas Zierer ◽  
Klas Lindblad ◽  
Jonas Larsson ◽  
Laurent deVito ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Pattern ◽  
Gas Turbine ◽  
Large Scale ◽  
Computational Effort ◽  
Special Focus ◽  
Computational Domain ◽  
3 Dimensional ◽  
Numerical Resolution ◽  
Cooling Air

The fluid flow in gas turbine rim seals and the sealing effectiveness are influenced by the interaction of the rotor and the stator disk and by the external flow in the hot gas annulus. The resulting flow structure is fully 3-dimensional and time-dependant. The requirements to a sufficiently accurate numerical prediction for front and back cavity flows are discussed in this paper. The results of different numerical approaches are presented for an axial seal configuration. This covers a full simulation of the time-dependant flow field in a 1.5 stage experimental turbine including the main annulus and both rim cavities. This configuration is simplified in subsequent steps in order to identify a method providing the best compromise between a sufficient level of accuracy and the least computational effort. A comparison of the computed cavity pressures and the sealing effectiveness with rig test data shows the suitability of each numerical method. The numerical resolution of a large scale rotating structure that is found in the front cavity is a special focus of this study. The existence of this flow pattern was detected first by unsteady pressure measurements in test rig. It persists within a certain range of cooling air massflows and significantly affects the sealing behaviour and the cavity pressure distribution. This phenomenon is captured with an unsteady calculation using a 360 deg. computational domain. The description of the flow pattern is given together with a comparison to the measurements.

Study on Improving the Flow in Forebay of the Pumping Station

2010 ◽  
Author(s):  
Chao Liu ◽  
Jiren Zhou ◽  
Li Cheng ◽  
Yan Jin ◽  
Xu Han
Keyword(s):  
Flow Pattern ◽  
Large Scale ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Flow Fields ◽  
Computational Results ◽  
Pumping Station ◽  
Flow Motion ◽  
Improved Design ◽  
Good Flow

The flow pattern in the forebay of pumping station is of very important influence on the operation of the pumps. The different kinds of unlike flow pattern, such as large scale circulations and vortices, are often found in the forebay of pumping station especially with multi-pumps. This paper takes the study on improving the flow pattern in the forebay to ensure a good flow condition for pumps operation. The computational results of three dimensional flow fields in an original designed forebay were obtained and a large circulation was found in the forebay on the side which caused serious problems to the operation of pumps. A typical combined means were applied to improve the flow motion. The computational results of the flow fields shows that the large circulation was eliminated and the flow distribution was improved, which was verified by the model test. The improved design has been successfully used to a large pumping station.

Large-scale flow field visualization for aneurysm treatment

2001 ◽  
Vol 9 (1) ◽  
pp. 3-7
Author(s):  
Damon Liu ◽  
Mark Burgin ◽  
Walter Karplus ◽  
Daniel Valentino
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Aneurysm Treatment ◽  
Large Scale Flow

scholarly journals Impact of the municipal merger on watershed management: a study of Lake Kasumigaura, Japan

2021 ◽  
Author(s):  
Takeshi Mizunoya ◽  
Noriko Nozaki ◽  
Rajeev Kumar Singh
Keyword(s):  
Watershed Management ◽  
Large Scale ◽  
Environmental Changes ◽  
Water Environment ◽  
Reduction Rate ◽  
Oxygen Demand ◽  
Policy Implications ◽  
Pollution Reduction ◽  
Lake Kasumigaura ◽  
The Impact

AbstractIn the early 2000s, Japan instituted the Great Heisei Consolidation, a national strategy to promote large-scale municipal mergers. This study analyzes the impact that this strategy could have on watershed management. We select the Lake Kasumigaura Basin, the second largest lake in Japan, for the case study and construct a dynamic expanded input–output model to simulate the ecological system around the Lake, the socio-environmental changes over the period, and their mutual dependency for the period 2012–2020. In the model, we regulate and control the following water pollutants: total nitrogen, total phosphorus, and chemical oxygen demand. The results show that a trade-off between economic activity and the environment can be avoided within a specific range of pollution reduction, given that the prefectural government implements optimal water environment policies, assuming that other factors constraining economic growth exist. Additionally, municipal mergers are found to significantly reduce the budget required to improve the water environment, but merger budget efficiency varies nonlinearly with the reduction rate. Furthermore, despite the increase in financial efficiency from the merger, the efficiency of installing domestic wastewater treatment systems decreases drastically beyond a certain pollution reduction level and eventually reaches a limit. Further reductions require direct regulatory instruments in addition to economic policies, along with limiting the output of each industry. Most studies on municipal mergers apply a political, administrative, or financial perspective; few evaluate the quantitative impact of municipal mergers on the environment and environmental policy implications. This study addresses these gaps.

scholarly journals Scaling up Studies on PEMFC Using a Modified Serpentine Flow Field Incorporating Porous Sponge Inserts to Observe Water Molecules

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 286
Author(s):  
Muthukumar Marappan ◽  
Rengarajan Narayanan ◽  
Karthikeyan Manoharan ◽  
Magesh Kannan Vijayakrishnan ◽  
Karthikeyan Palaniswamy ◽  
...  
Keyword(s):  
Flow Field ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Scaling Up ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Experimental Investigations ◽  
Serpentine Flow Field ◽  
Exchange Membrane ◽  
Power Densities

Flooding of the cathode flow channel is a major hindrance in achieving maximum performance from Proton Exchange Membrane Fuel Cells (PEMFC) during the scaling up process. Water accumulated between the interface region of Gas Diffusion Layer (GDL) and rib of the cathode flow field can be removed by the use of Porous Sponge Inserts (PSI) on the ribs. In the present work, the experimental investigations are carried out on PEMFC for the various reaction areas, namely 25, 50 and 100 cm2. Stoichiometry value of 2 is maintained for all experiments to avoid variations in power density obtained due to differences in fuel utilization. The experiments include two flow fields, namely Serpentine Flow Field (SFF) and Modified Serpentine with Staggered provisions of 4 mm PSI (4 mm × 2 mm × 2 mm) Flow Field (MSSFF). The peak power densities obtained on MSSFF are 0.420 W/cm2, 0.298 W/cm2 and 0.232 W/cm2 compared to SFF which yields 0.242 W/cm2, 0.213 W/cm2 and 0.171 W/cm2 for reaction areas of 25, 50 and 100 cm2 respectively. Further, the reliability of experimental results is verified for SFF and MSSFF on 25 cm2 PEMFC by using Electrochemical Impedance Spectroscopy (EIS). The use of 4 mm PSI is found to improve the performance of PEMFC through the better water management.

scholarly journals Instability wave models for the near-field fluctuations of turbulent jets

2011 ◽  
Vol 689 ◽  
pp. 97-128 ◽  
Author(s):  
K. Gudmundsson ◽  
Tim Colonius
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Microphone Array ◽  
Near Field ◽  
Turbulent Jets ◽  
Instability Wave ◽  
Mean Flow ◽  
Velocity Fluctuations ◽  
The Mean ◽  
Scale Structures

AbstractPrevious work has shown that aspects of the evolution of large-scale structures, particularly in forced and transitional mixing layers and jets, can be described by linear and nonlinear stability theories. However, questions persist as to the choice of the basic (steady) flow field to perturb, and the extent to which disturbances in natural (unforced), initially turbulent jets may be modelled with the theory. For unforced jets, identification is made difficult by the lack of a phase reference that would permit a portion of the signal associated with the instability wave to be isolated from other, uncorrelated fluctuations. In this paper, we investigate the extent to which pressure and velocity fluctuations in subsonic, turbulent round jets can be described aslinearperturbations to the mean flow field. The disturbances are expanded about the experimentally measured jet mean flow field, and evolved using linear parabolized stability equations (PSE) that account, in an approximate way, for the weakly non-parallel jet mean flow field. We utilize data from an extensive microphone array that measures pressure fluctuations just outside the jet shear layer to show that, up to an unknown initial disturbance spectrum, the phase, wavelength, and amplitude envelope of convecting wavepackets agree well with PSE solutions at frequencies and azimuthal wavenumbers that can be accurately measured with the array. We next apply the proper orthogonal decomposition to near-field velocity fluctuations measured with particle image velocimetry, and show that the structure of the most energetic modes is also similar to eigenfunctions from the linear theory. Importantly, the amplitudes of the modes inferred from the velocity fluctuations are in reasonable agreement with those identified from the microphone array. The results therefore suggest that, to predict, with reasonable accuracy, the evolution of the largest-scale structures that comprise the most energetic portion of the turbulent spectrum of natural jets, nonlinear effects need only be indirectly accounted for by considering perturbations to the mean turbulent flow field, while neglecting any non-zero frequency disturbance interactions.

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