A Single-Stage Centripetal Pump—Design Features and an Investigation of the Operating Characteristics

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Mihael Sekavčnik ◽  
Tine Gantar ◽  
Mitja Mori
Keyword(s):  
Single Stage ◽  
Flow Conditions ◽  
Operating Characteristics ◽  
Cfd Simulations ◽  
Pump Design ◽  
Flow Channels ◽  
Performance Curves ◽  
Computational Fluid Dynamics Cfd ◽  
Working Media ◽  
Inflow Conditions

In this paper, we present an experimental and numerical investigation of a single-stage centripetal pump (SSCP). This SSCP is designed to operate in the pump regime, while forcing the working media through impeller-stator flow channels in the radial inward direction. The measured performance curves are characterized by a hysteresis, since the throttle-closing performance curves do not correspond to the throttle-opening performance curves throughout the whole operating range. A computational fluid dynamics (CFD) model was developed to establish these throttle-closing and throttle-opening performance curves. The flow conditions obtained with the CFD simulations confirm that the hydraulic behavior of the SSCP is influenced by the partial circumferential stall that occurs in the impeller-stator flow channels. It was shown that the inflow conditions to the impeller-stator assembly considerably influence the flow rate of the stall cessation, the size of the hysteresis, and the head generated during part-load operations.

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 73 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

A Systematical Study of the Influence of Blade Number on the Performance of a Side Channel Pump

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Annika Fleder ◽  
Martin Böhle
Keyword(s):  
Experimental Studies ◽  
Numerical Results ◽  
Channel Height ◽  
Side Channel ◽  
Outer Diameter ◽  
Cfd Simulations ◽  
Blade Number ◽  
Performance Curves ◽  
Flow Phenomena ◽  
Computational Fluid Dynamics Cfd

For side channel machines, distinction is made between side channel pumps and peripheral pumps. The blade number of side channel machines has a large influence on the performance of the pump. This is known from several experimental studies. For industrial side channel pumps, the blade number is between 20 and 26, whereas for industrial peripheral pumps, the blade number is much larger (between 36 and 90). In this paper, the influence of the blade number on the performance and the inner flow phenomena of different pumps will be investigated experimentally and numerically. The inner flow of the pump is examined in detail by computational fluid dynamics (CFD) simulations. Flow angles and velocities of the circulation flow between side channel and impeller are considered for different blade numbers. To explain the influences of the blade number, numerical results and theoretical formulas are combined. The experiments are carried out for two different modular side channel pump units, which differ in the side channel height h, the outer impeller diameter da, and the length of the blades l. So, the influence of the blade number can be studied in the context of other parameters like, for example, the relation between blade length and outer diameter of the pump. The obtained numerical results are compared with experimental data. Effects of the blade number on the performance curves of the pumps are shown by experimental and numerical results.

Energy Efficiency of an Axial Fan for Various Casing Configurations

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Alain Guedel ◽  
Mirela Robitu ◽  
Vivian Chaulet
Keyword(s):  
Energy Efficiency ◽  
Axial Fan ◽  
Cfd Simulations ◽  
Fan Performance ◽  
Commercial Code ◽  
Performance Curves ◽  
Commission Regulation ◽  
Target Energy ◽  
Parametric Studies ◽  
Computational Fluid Dynamics Cfd

The objective of this paper is to compare the measured and predicted performances of a tubeaxial fan for several casing configurations that are commonly proposed by fan manufacturers to their clients. This work is motivated by the European Commission Regulation 327/2011, which will impose target energy efficiency for fans driven by electric motors beginning 1 January 2013. The prediction is made with the computational fluid dynamics (CFD) commercial code STAR-CCM+. The agreement between the experimental and numerical results on fan performance curves is very satisfactory, which confirms that CFD simulations may advantageously replace testing in parametric studies since they predict the quantitative differences of aerodynamic performance observed experimentally between the different casing configurations quite well. Numerical simulations may, therefore, help manufacturers to improve the geometry of their fans in order to fulfill the requirements of the regulation.

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

2018 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

scholarly journals Remedial Solutions to Control Excessive Propeller Induced Hull Vibrations on a Landing Craft

2018 ◽  
Author(s):  
M Fan ◽  
B Aktas ◽  
W Shi ◽  
N Sasaki ◽  
P Fitzsimmons ◽  
...  
Keyword(s):  
Arabian Gulf ◽  
Flow Conditions ◽  
Power Performance ◽  
Gulf Region ◽  
Cfd Simulations ◽  
Flat Bottom ◽  
Hull Form ◽  
Propulsive Efficiency ◽  
Arabian Gulf Region ◽  
Computational Fluid Dynamics Cfd

Although landing craft are not sophisticated vessels, their functional/operational requirements often result in a hull shape which may encounter unusual hydrodynamic phenomena, requiring remedial attention. One such instance is discussed in this paper, which presents hull form solutions adopted to address excessive vibration experienced on-board an enhanced landing craft operating in the Arabian Gulf region. Through Computational Fluid Dynamics (CFD) simulations, the sources of excessive vibration experienced by this vessel were identified. The sources included the current bow design, which promoted aeration; an extensive flat bottom, which channelled the air to a shallow buttock-flow stern region; angled pram type stern fitted with blunt-ended appendages generated a non-uniform flow that was too severe for the existing propeller-hull clearances. The combination of these unfavourable flow conditions with the cavitating propellers resulted in undesirable Propeller-Hull Vortex Cavitation (PHVC) which manifested itself with excessive aft end vibrations and noise. To remedy the situation and to control the excessive vibrations, further CFD simulations guided the necessary hull form modifications. The identified countermeasures included anti-Propeller Hull Vortex (PHV) plates and streamlining of stern appendages. Subsequent sea trials showed horizontal vibration levels were reduced by 85%, which significantly improved the conditions on-board. This paper presents a technical summary of the above countermeasures, their implementations on the vessel, which included full-scale trials to measure the speed-power performance, hull vibrations and cavitation observations using a borescope system, and discussions of the results of these countermeasures. The paper concludes with an outline proposal for further design study, which could reduce on-board vibrations even further as well as providing other operational benefits regarding propulsive efficiency and manoeuvrability using the recently developed “Gate Rudder System ®” as a novel Energy Saving Device (ESD).

CFD Predictions and Experiments of Erosion of Elbows in Series in Liquid Dominated Flows

2018 ◽  
Author(s):  
Thiana A. Sedrez ◽  
Yeshwanth R. Rajkumar ◽  
Siamack A. Shirazi ◽  
Hadi Arabnejad Khanouki ◽  
Brenton S. McLaury
Keyword(s):  
Solid Particle Erosion ◽  
Flow Conditions ◽  
Erosion Modeling ◽  
Cfd Simulations ◽  
Horizontal Orientation ◽  
In Series ◽  
Computational Fluid Dynamics Cfd ◽  
Sand Flow ◽  
Pattern Visualization ◽  
Good Agreement

Most previous studies of solid particle erosion in elbows considered an elbow for which the upstream length is long (L/D>100) and flow is well developed before reaching the elbow. But, in this study, experiments were conducted for two elbows in series, one in vertical upward-horizontal orientation and the second one placed after L/D = 6 in horizontal-vertical downward orientation. Erosion experiments were conducted with liquid-sand and liquid-gas-sand flow conditions in an experimental facility with two test section configurations: metallic elbows in series for erosion measurements and acrylic elbows in series for erosion pattern visualization. The experiments include erosion measurements of both metallic elbows with ultrasonic wall thickness (UT) measurements. All experiments including flow visualization of erosion pattern were conducted for both elbows for liquid dominated flows, and the results comparing the erosion ratio of the second elbow to the first elbow are presented. In addition, Computational Fluid Dynamics (CFD) simulations have been performed and compared to the experimental erosion patterns with both erosion pattern visualization and UT measurements. The results show good agreement between experiments and CFD simulations and experimental results provide a database for improving erosion modeling in liquid dominated flows.

CFD as a Design Tool for Hydrodynamic Loading on Offshore Structures

2009 ◽  
Author(s):  
Sampath Atluri ◽  
Allan Magee ◽  
Kostas Lambrakos
Keyword(s):  
Time Domain ◽  
Equations Of Motion ◽  
Offshore Structures ◽  
Design Tool ◽  
Flow Conditions ◽  
Floating Platform ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
The Time Domain ◽  
The Given

Time-domain numerical integration of the rigid body equations of motion is a popular choice for analyzing the global motions of a single or multi-module floating platform. Potential flow theory cannot accurately account for all the hydrodynamic forces on certain components of the platform. However, for practical analysis, these members can be modeled as Morison members in the time-domain simulations. Computational Fluid Dynamics (CFD) can be used to calculate Morison coefficients for the given flow conditions on the exact geometry of the member. This paper presents the results from CFD simulations performed on several individual components of a floating platform (like heave plates, truss members etc.,) in realistic environment conditions. The procedure used for extracting the linear and non-linear coefficients from the total calculated hydrodynamic force is also explained. Results from CFD are compared to existing published experimental results. Differences between full-scale and model-scale results will be emphasized where important. Some of the advantages of using CFD as opposed to model tests are highlighted.

Discussion: “Unsteady RANS Simulations of Wells Turbine Under Transient Flow Conditions” (Hu and Li, ASME J. Offshore Mech. Arct. Eng., 140(1), p. 011901)

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Tiziano Ghisu ◽  
Francesco Cambuli ◽  
Pierpaolo Puddu ◽  
Irene Virdis ◽  
Mario Carta
Keyword(s):  
Transient Flow ◽  
Careful Consideration ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Wells Turbine ◽  
Numerical Errors ◽  
Performance Curves ◽  
Unsteady Rans ◽  
Computational Fluid Dynamics Cfd ◽  
Rans Simulations

The work by Hu and Li (2018, “Unsteady RANS Simulations of Wells Turbine Under Transient Flow Conditions,” ASME J. Offshore Mech. Arct. Eng., 140(1), p. 011901) presents the numerical simulation of a high-solidity Wells turbine by means of a computational fluid dynamics (CFD) (Reynolds-averaged Navier–Stokes (RANS)) approach. A key aspect highlighted by the authors is the presence of a hysteretic loop in the machine's performance curves, due (according to their explanation) to the interaction of vortices shed by the blade with the blade circulation, which is responsible for the aerodynamic forces. It is our opinion that this work contains some serious errors that invalidate the results. In this brief discussion, we aim to demonstrate how the hysteresis found and discussed by the authors should not be present in the turbine analyzed in Hu and Li (2018, “Unsteady RANS Simulations of Wells Turbine Under Transient Flow Conditions,” ASME J. Offshore Mech. Arct. Eng., 140(1), p. 011901), and it is unlikely to be present in any Wells turbine. The fact that Hu and Li find hysteresis in their simulations is most likely caused by numerical errors due to an insufficient temporal discretization. This and other inaccuracies could have been avoided with a more careful consideration of the available literature.

scholarly journals Using CFD to Evaluate Natural Ventilation through a 3D Parametric Modeling Approach

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2197
Author(s):  
Nayara Rodrigues Marques Sakiyama ◽  
Jurgen Frick ◽  
Timea Bejat ◽  
Harald Garrecht
Keyword(s):  
Natural Ventilation ◽  
Parametric Modeling ◽  
Cfd Simulations ◽  
3D Design ◽  
Post Process ◽  
Test House ◽  
Model Set ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Passive Strategy

Predicting building air change rates is a challenge for designers seeking to deal with natural ventilation, a more and more popular passive strategy. Among the methods available for this task, computational fluid dynamics (CFD) appears the most compelling, in ascending use. However, CFD simulations require a range of settings and skills that inhibit its wide application. With the primary goal of providing a pragmatic CFD application to promote wind-driven ventilation assessments at the design phase, this paper presents a study that investigates natural ventilation integrating 3D parametric modeling and CFD. From pre- to post-processing, the workflow addresses all simulation steps: geometry and weather definition, including incident wind directions, a model set up, control, results’ edition, and visualization. Both indoor air velocities and air change rates (ACH) were calculated within the procedure, which used a test house and air measurements as a reference. The study explores alternatives in the 3D design platform’s frame to display and compute ACH and parametrically generate surfaces where air velocities are computed. The paper also discusses the effectiveness of the reference building’s natural ventilation by analyzing the CFD outputs. The proposed approach assists the practical use of CFD by designers, providing detailed information about the numerical model, as well as enabling the means to generate the cases, visualize, and post-process the results.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

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