scholarly journals Research on Three-Dimensional Unsteady Turbulent Flow in Multistage Centrifugal Pump and Performance Prediction Based on CFD

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Zhi-jian Wang ◽  
Jian-she Zheng ◽  
Lu-lu Li ◽  
Shuai Luo
Keyword(s):  
Turbulent Flow ◽  
Centrifugal Pump ◽  
Total Pressure ◽  
Guide Vane ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Flow Region ◽  
Separation Flow ◽  
Multistage Centrifugal Pump ◽  
Simulation Results

The three-dimensional flow physical model of any stage of the 20BZ4 multistage centrifugal pump is built which includes inlet region, impeller flow region, guide-vane flow region and exit region. The three-dimensional unsteady turbulent flow numerical model is created based on Navier-Stoke solver and standardk-εturbulent equations. The method of multireference frame (MRF) and SIMPLE algorithm are used to simulate the flow in multistage centrifugal pump based on FLUENT software. The distributions of relative velocity, absolute velocity, static pressure, and total pressure in guide vanes and impellers under design condition are analyzed. The simulation results show that the flow in impeller is mostly uniform, without eddy, backflow, and separation flow, and jet-wake phenomenon appears only along individual blades. There is secondary flow at blade end and exit of guide vane. Due to the different blade numbers of guide vane and impeller, the total pressure distribution is asymmetric. This paper also simulates the flow under different working conditions to predict the hydraulic performances of centrifugal pump and external characteristics including flow-lift, flow-shaft power, and flow-efficiency are attained. The simulation results are compared with the experimental results, and because of the mechanical losses and volume loss ignored, there is a little difference between them.

scholarly journals Effect of an Inducer-Type Guide Vane on Hydraulic Losses at the Inter-Stage Flow Passage of a Multistage Centrifugal Pump

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 526
Author(s):  
Mohamed Murshid Shamsuddeen ◽  
Sang-Bum Ma ◽  
Sung Kim ◽  
Ji-Hoon Yoon ◽  
Kwang-Hee Lee ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Guide Vane ◽  
Three Dimensional ◽  
Design Flow ◽  
Hydraulic Losses ◽  
Second Stage ◽  
Multistage Centrifugal Pump ◽  
Overall Performance ◽  
High Head

A multistage centrifugal pump was developed for high head and high flow rate applications. A double-suction impeller and a twin-volute were installed at the first stage followed by an impeller, diffuser and return vanes for the next four stages. An initial design feasibility study was conducted using three-dimensional computational fluid dynamics tools to study the performance and the hydraulic losses associated with the design. Substantial losses in head and efficiency were observed at the interface between the first stage volute and the second stage impeller. An inducer-type guide vane (ITGV) was installed at this location to mitigate the losses by reducing the circumferential velocity of the fluid exiting the volute. The ITGV regulated the pre-swirl of the fluid entering the second stage impeller. The pump with and without ITGV is compared at the design flow rate. The pump with ITGV increased the stage head by 63.28% and stage efficiency by 47.17% at the second stage. As a result, the overall performance of the pump increased by 5.78% and 3.94% in head and efficiency, respectively, at the design point. The ITGV has a significant impact on decreasing losses at both design and off-design conditions. An in-depth flow dynamic analysis at the inducer-impeller interface is also presented.

Pressure and Flow Rate Fluctuations in Single- and Two-Blade Pumps

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Andreas Pesch ◽  
Steffen Melzer ◽  
Stephan Schepeler ◽  
Tobias Kalkkuhl ◽  
Romuald Skoda
Keyword(s):  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Electromagnetic Flowmeter ◽  
Flow Region ◽  
Mean Values ◽  
Wall Pressure Fluctuations ◽  
Simulation Results ◽  
Blade Pump

Abstract A comparative study on the highly unsteady flow field in single- and two-blade pumps is performed. Stationary pump characteristics, as well as pressure and flow rate fluctuations, are presented. Wall pressure fluctuations were measured in the suction and pressure pipe as well as at several locations within the volute casing by piezoresistive transducers. Flow rate fluctuations were evaluated by a recently presented measurement system based on an electromagnetic flowmeter (Melzer et al. 2020, “A System for Time-Fluctuating Flow Rate Measurements in a Single-Blade Pump Circuit,” Flow Meas. Instrum., 71, p. 101675). Measurements were accompanied by three-dimensional (3D) flow simulations with the open-source cfd software foam-extend. A thorough grid study and validation of the simulation were performed. By a complementary analysis of measurement and simulation results, distinctive differences between both pump types were observed, e.g., flow rate and pressure fluctuation magnitudes are significantly higher in the single-blade pump. In relation to the respective mean values, flow rate fluctuation magnitudes are one order lower than pressure fluctuation magnitudes for both pumps. For the two-blade pump, fluctuations attenuate toward overload irrespective of the particular pump circuit, while they rise for the single-blade pump. 3D simulation results yield detailed insight into the spatially and temporally resolved impeller–volute interaction and reveal that the single-blade impeller pushes a high-pressure flow region forward in a way as a positive displacement pump, resulting in an inherently fluctuating velocity and pressure distribution within the volute.

Calculation of Three-Dimensional Viscous Flow in Hydrodynamic Torque Converters

1996 ◽  
Vol 118 (3) ◽  
pp. 578-589 ◽  
Author(s):  
H. Schulz ◽  
R. Greim ◽  
W. Volgmann
Keyword(s):  
Viscous Flow ◽  
Guide Vane ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Mass Conservation ◽  
Computer Code ◽  
Torque Converter ◽  
Turbine Rotor ◽  
Incompressible Viscous Flow ◽  
Vector Computers

A numerical method for calculating three-dimensional, steady or unsteady, incompressible, viscous flow is described. The conservation equations for mass and momentum and the equations of the k–ε turbulence model are solved with a finite volume method on nonorthogonal boundary-fitted grids. The method employs cell-centered variable arrangement and Cartesian velocity components. The SIMPLE algorithm is used to calculate the pressure and to enforce mass conservation. The computer code is vectorizable as far as possible to achieve an optimal performance on modern vector computers. Results of steady flow calculations in the guide vane, the pump rotor, and the turbine rotor and of the unsteady interaction simulation of the pump and the turbine of a one-stage one-phase non-automotive hydrodynamic torque converter are presented.

Effects of axial length and integrated design on the aggressive intermediate turbine duct

2018 ◽  
Vol 233 (4) ◽  
pp. 443-456 ◽  
Author(s):  
Qingzong Xu ◽  
Pei Wang ◽  
Qiang Du ◽  
Jun Liu ◽  
Guang Liu
Keyword(s):  
Boundary Layer ◽  
High Pressure ◽  
Secondary Flow ◽  
Axial Length ◽  
Pressure Loss ◽  
Total Pressure ◽  
Guide Vane ◽  
Three Dimensional ◽  
Intermediate Turbine Duct ◽  
Aero Engine

With the increasing demand of high bypass ratio and thrust-to-weight ratio in civil aero-engine, the intermediate turbine duct between the high pressure and low pressure turbines of a modern gas turbine tends to shorter axial length, larger outlet-to-inlet area ratio and high pressure-to-low pressure radial offset. This paper experimentally and numerically investigated the three-dimensional flow characteristics of traditional (ITD1) and aggressive intermediate turbine duct (ITD2) at low Reynolds number. The baseline case of ITD1 is representative of a traditional intermediate turbine duct of aero-engine design with non-dimensional length of L/dR = 2.79 and middle angle of 20.12°. The detailed flow fields inside ITD1 and flow visualization were measured. Results showed the migration of boundary layer and a pair of counter-rotating vortexes were formed due to the radial migration of low momentum fluid. With the decreasing axial length of intermediate turbine duct, the radial and streamwise reverse pressure gradient in aggressive intermediate turbine duct (ITD2) were increased resulting in severe three-dimensional separation of boundary layer near casing surface and higher total pressure loss. The secondary flow and separation of boundary layer near the endwall were deeply analyzed to figure out the main source of high total pressure loss in the aggressive intermediate turbine duct (ITD2). Based on that, employing wide-chord guide vane to substitute “strut + guide vane”, this paper designed the super-aggressive intermediate turbine duct and realized the suppression of the three-dimensional separation and secondary flow.

Influence of Rotor-Stator Interaction on Flow Stability in Centrifugal Pump Based on Energy Gradient Method

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Lu-Lu Zheng ◽  
Hua-Shu Dou ◽  
Wei Jiang ◽  
Xiaoping Chen ◽  
Zuchao Zhu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Energy Gradient ◽  
Rotor Stator Interaction ◽  
Volume Method

AbstractNumerical simulation is performed for the three-dimensional turbulent flow field in a centrifugal pump by solving the Reynolds-averaged Navier-Stokes equations and the RNG k-epsilon turbulent model. The finite volume method and the SIMPLE algorithm are employed for the solution of the system. All the parameters in the centrifugal pump at different blade angular positions are obtained by simulation. The flow structure is analyzed and the distributions of the energy gradient function

scholarly journals Calculation of Three-Dimensional Viscous Flow in Hydrodynamic Torque Converters

1994 ◽  
Author(s):  
H. Schulz ◽  
R. Greim ◽  
W. Volgmann
Keyword(s):  
Viscous Flow ◽  
Guide Vane ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Mass Conservation ◽  
Computer Code ◽  
Torque Converter ◽  
Turbine Rotor ◽  
Incompressible Viscous Flow ◽  
Vector Computers

A numerical method for calculating threedimensional, steady or unsteady, incompressible, viscous flow is described. The conservation equations for mass and momentum and the equations of the kε-turbulence model are solved with a finite volume method on nonorthogonal boundary-fitted grids. The method employs cell-centered variable arrangement and Cartesian velocity components. The SIMPLE-algorithm is used to calculate the pressure and to enforce mass conservation. The computer code is vectorizable as far as possible to achieve an optimal performance on modern vector computers. Results of steady flow calculations in the guide vane, the pump rotor and the turbine rotor and of the unsteady interaction simulation of the pump and the turbine of a one-stage one-phase non-automotive hydrodynamic torque converter are presented.

scholarly journals Effects on magnetic reconnection of a density asymmetry across the current sheet

2008 ◽  
Vol 26 (8) ◽  
pp. 2471-2483 ◽  
Author(s):  
K. G. Tanaka ◽  
A. Retinò ◽  
Y. Asano ◽  
M. Fujimoto ◽  
I. Shinohara ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Three Dimensional ◽  
Flow Region ◽  
Electron Acceleration ◽  
Particle In Cell ◽  
Line Structure ◽  
Simulation Results

Abstract. The magnetopause (MP) reconnection is characterized by a density asymmetry across the current sheet. The asymmetry is expected to produce characteristic features in the reconnection layer. Here we present a comparison between the Cluster MP crossing reported by Retinò et al. (2006) and virtual observations in two-dimensional particle-in-cell simulation results. The simulation, which includes the density asymmetry but has zero guide field in the initial condition, has reproduced well the observed features as follows: (1) The prominent density dip region is detected at the separatrix region (SR) on the magnetospheric (MSP) side of the MP. (2) The intense electric field normal to the MP is pointing to the center of the MP at the location where the density dip is detected. (3) The ion bulk outflow due to the magnetic reconnection is seen to be biased towards the MSP side. (4) The out-of-plane magnetic field (the Hall magnetic field) has bipolar rather than quadrupolar structure, the latter of which is seen for a density symmetric case. The simulation also showed rich electron dynamics (formation of field-aligned beams) in the proximity of the separatrices, which was not fully resolved in the observations. Stepping beyond the simulation-observation comparison, we have also analyzed the electron acceleration and the field line structure in the simulation results. It is found that the bipolar Hall magnetic field structure is produced by the substantial drift of the reconnected field lines at the MSP SR due to the enhanced normal electric field. The field-aligned electrons at the same MSP SR are identified as the gun smokes of the electron acceleration in the close proximity of the X-line. We have also analyzed the X-line structure obtained in the simulation to find that the density asymmetry leads to a steep density gradient in the in-flow region, which may lead to a non-stationary behavior of the X-line when three-dimensional freedom is taken into account.

scholarly journals Numerical Simulation of Temperature Decrease in Greenhouses with Summer Water-Sprinkling Roof

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2435 ◽  
Author(s):  
Jiaming Guo ◽  
Yanhua Liu ◽  
Enli Lü
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Discrete Ordinates ◽  
Multiphase Model ◽  
Temperature Decrease ◽  
Turbulent Model ◽  
Flow Rates ◽  
Symmetrical Model ◽  
Simulation Results

Decreasing the temperature of a greenhouse in summer is very important for the growth of plants. To investigate the effects of a roof sprinkler on the heat environment of a greenhouse, a three-dimensional symmetrical model was built, in which a k-ε (k-epsilon) turbulent model, a DO (Discrete Ordinates) irrational model, a Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm, and a multiphase model were used to simulate the effects of the roof sprinkler, at different flow rates. Based on the simulation results, it was found that the temperature could be further reduced under a proper sprinkle rate, and the temperature distribution in the film on the roof was more uniform. A test was conducted to verify the accuracy of the model, which proved the validity of the numerical results. The simulation results of this study will be helpful for controlling and optimizing the heat environment of a greenhouse.

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