Numerical Simulation of the Flow in a Centrifugal Pump With a Vaned Diffuser

2011 ◽  
Author(s):  
Willian Segala ◽  
Henrique Stel ◽  
Vanessa Hungria ◽  
Rigoberto E. M. Morales ◽  
Sergio C. Vicent ◽  
...  
Keyword(s):  
Numerical Model ◽  
Centrifugal Pump ◽  
Single Stage ◽  
Computational Time ◽  
Periodic Regime ◽  
Two Stage ◽  
Vaned Diffuser ◽  
Similarity Relations ◽  
Wide Range ◽  
Good Agreement

This work presents a numerical investigation of the water flow in the first stage of a two-stage centrifugal pump with a vaned diffuser. The geometry consists of a pipe intake, a 8-blade impeller, a 12-blade diffuser and an outlet extension chamber. The numerical modeling comprises a transient rotorstator interface connection between the impeller and the other static domains, and it was implemented in the commercial code ANSYS-CFX. The numerical runs were carried out for four impeller speeds and a wide range of volumetric flow rates. The standard k-ε turbulence model was used. An experimental loop is also used to measure pump head values to validate the numerical approach. Comparison of numerical head values with the experimental data showed a good agreement. Similarity relations used for the numerical head values for different impeller speeds also shows good agreement within the range studied. A transient analysis of the pressure values at the impeller-diffuser interface showed that, using a steady state frozen rotor approximation as the initial condition for the transient calculation, generally no more than half of a complete impeller revolution is needed for the pump to achieve temporal periodicity. This numerical procedure saves significantly the computational time. Moreover, the numerical results confirm that, once the periodic regime is achieved, an azimuthal periodicity at each 90° interval is also achieved, just as expected from the 8-to-12 blades ratio between impeller and diffuser. Comparison of the numerical efficiencies of the single-stage pump with the experimental counterpart showed significant discrepancies. These must be related to the geometric simplifications of the numerical model and volumetric pressure losses of the real pump not included in the numerical model. Consequently, the Best Efficiency Point of the single-stage pump was found to be different from the two-stage assembly, and the flow field analysis apparently confirms this feature.

Numerical Analysis of the Fluid Flow in the First Stage of a Two-Stage Centrifugal Pump With a Vaned Diffuser

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
H. Stel ◽  
G. D. L. Amaral ◽  
C. O. R. Negrão ◽  
S. Chiva ◽  
V. Estevam ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Flow Pattern ◽  
Centrifugal Pump ◽  
Pressure Rise ◽  
Single Equation ◽  
Two Stage ◽  
Vaned Diffuser ◽  
Flow Rates ◽  
Wide Range ◽  
Pump Head

This work presents a numerical investigation of the fluid flow in the first stage of a two-stage centrifugal pump with a vaned diffuser. A computational fluid dynamics (CFD) analysis is performed by using the ANSYS-CFX software for a wide range of volumetric flow rates and also for different rotor speeds. The numerical results are validated against measured values of pressure rise through the impeller and diffuser of the first stage with an overall good agreement. Nevertheless, not only the best efficiency point evaluated numerically is overestimated in comparison with the measured two-stage pump values but also the computed hydraulic efficiency of the first stage. Investigation of the flow pattern for different flow rates reveals that the flow becomes badly oriented for part-load conditions. In such cases, significant levels of turbulence and blade orientation effects are observed, mainly in the diffuser. In spite of different flow rates or rotor speeds, the flow pattern is quite similar if the flow dimensionless coefficient is kept constant, showing that classical similarity rules can be applied in this case. By using such rules, it was also possible to derive a single equation for the pump head to represent the whole operational range of the pump.

Numerical Research of the Effect of the Outlet Diameter of Diffuser on the Performance and the Radial Force in a Single-Stage Centrifugal Pump

2014 ◽  
Author(s):  
Jiang Wei ◽  
Li Guojun ◽  
Liu Pengfei ◽  
Zhang Lisheng ◽  
Qing Hongyang
Keyword(s):  
Centrifugal Pump ◽  
Radial Force ◽  
Numerical Results ◽  
Operating Conditions ◽  
Single Stage ◽  
Navier Stokes ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Vaned Diffuser ◽  
Unsteady Numerical Simulation

In this paper, a single-stage pump with diffuser vanes of different outlet diameters has been investigated both numerically and experimentally. The influence of the diffuser vane outlet diameter on pump hydraulic performance and on the radial force of the impeller is explored. Pumps equipped with three different diffusers but with impellers and volutes of the same parameters were simulated by 3D Navier-Stokes solver ANSYS-FLUENT in order to study the effect of the outlet diameter of vaned diffuser on performance of the centrifugal pump. Structured grids of high quality were applied on the whole computational domain. Experimental results were acquired by prototype experiments and were then compared with the numerical results. Both experimental and numerical results show that the performance of a pump with a diffuser of smaller outlet diameter is better than of bigger outlet diameter under all operating conditions. The radial force imposed on the impeller obtained by unsteady numerical simulation was analyzed. The results also indicated that an appropriate decrease in the outlet diameter of the diffuser vane could increase the radial force.

Unsteady Flow Structure on a Centrifugal Pump: Experimental and Numerical Approaches

2002 ◽  
Author(s):  
Jose´ Gonza´lez ◽  
Carlos Santolaria ◽  
Eduardo Blanco ◽  
Joaqui´n Ferna´ndez
Keyword(s):  
Numerical Model ◽  
Centrifugal Pump ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Side Wall ◽  
Relative Effect ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Blade Passing Frequency ◽  
Wide Range

Both experimental and numerical studies of the unsteady pressure field inside a centrifugal pump have been carried out. The unsteady patterns found for the pressure fluctuations are compared and a further and more detailed flow study from the numerical model developed will be presented in this paper. Measurements were carried out with pressure transducers installed on the volute shroud. At the same time, the unsteady pressure field inside the volute of a centrifugal pump has been numerically modelled using a finite volume commercial code and the dynamic variables obtained have been compared with the experimental data available. In particular, the amplitude of the fluctuating pressure field in the shroud side wall of the volute at the blade passing frequency is successfully captured by the model for a wide range of operating flow rates. Once the developed numerical model has shown its capability in describing the unsteady patterns experimentally measured, an explanation for such patterns is searched. Moreover, the possibilities of the numerical model can be extended to other sections (besides the shroud wall of the volute), which can provide plausible explanations for the dynamic interaction effects between the flow at the impeller exit and the volute tongue at different axial positions. The results of the numerical simulation are focused in the blade passing frequency in order to study the relative effect of the two main phenomena occurring at that frequency for a given position: the blade passing in front of the tongue and the wakes of the blades.

scholarly journals Numerical Research on the Energy Loss of a Single-Stage Centrifugal Pump with Different Vaned Diffuser Outlet Diameters

2019 ◽  
Vol 158 ◽  
pp. 5523-5528 ◽  
Author(s):  
Fen Lai ◽  
Xiangyuan Zhu ◽  
Guojun Li ◽  
Liping Zhu ◽  
Fengming Wang
Keyword(s):  
Energy Loss ◽  
Centrifugal Pump ◽  
Single Stage ◽  
Vaned Diffuser ◽  
Numerical Research

scholarly journals Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6794
Author(s):  
Zhou Yan ◽  
Hany Hassanin ◽  
Mahmoud Ahmed El-Sayed ◽  
Hossam Mohamed Eldessouky ◽  
Joy Rizki Pangestu Djuansjah ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Processing Time ◽  
Incremental Forming ◽  
Single Point ◽  
Computational Time ◽  
Single Point Incremental Forming ◽  
Two Stage ◽  
Element Analysis ◽  
Wide Range

Single-point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. The mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively.

A Theoretical and Experimental Investigation of a Gas Dynamic Model for a Single Stage Reciprocating Compressor with Intake and Delivery Pipe Systems

1972 ◽  
Vol 14 (4) ◽  
pp. 264-279 ◽  
Author(s):  
R. S. Benson ◽  
A. Ş. Üçer
Keyword(s):  
Experimental Investigation ◽  
Delivery Systems ◽  
Wave Action ◽  
Single Stage ◽  
Reciprocating Compressor ◽  
Gas Dynamic ◽  
Test Conditions ◽  
Wide Range ◽  
Delivery Pipe ◽  
Good Agreement

A method is described for simulating a single stage reciprocating compressor. A model is developed which allows for wave action in the intake and delivery systems, and drag and inertia of the valves. It is shown that homentropic theory may be used for the wave action, provided a correction is made for the entropy changes across the valve. The results are given of an experimental investigation in which the pressures in the intake and delivery systems, the cylinder pressures, the mass flow and the valve movement were compared with the predictions using the model. Good agreement was obtained over the wide range of test conditions.

Modifications of a Two Stage Centrifugal Compressor for the Volute and Vaneless Diffuser Study

2001 ◽  
Author(s):  
Hooman Rezaei ◽  
Abraham Engeda ◽  
Paul Haley
Keyword(s):  
Flow Structure ◽  
Centrifugal Compressor ◽  
Single Stage ◽  
Vaneless Diffuser ◽  
Two Stage ◽  
Loss Mechanism ◽  
Vaned Diffuser ◽  
Fluid Medium ◽  
Laboratory Environment ◽  
Testing Facility

Abstract The objective of this work was to establish an advanced testing facility for studying the flow structure and loss mechanism in a single stage centrifugal compressor. A Trane’s CVHF 1280, two stage centrifugal compressor was modified to a single stage for laboratory environment. This modification included new fluid medium, driving motor, inlet and outlet designs. In this study, experiments were performed in order to evaluate the performance of the vaneless diffuser and volute. However, the modifications enable the flow structure investigation in all components of the compressor as well. In addition the testing facility would accommodate installation of the rest of the unit for investigation of the flow in the vaned diffuser and return channel of the two-stage compressor in the laboratory environment. Experiments were performed in three speeds and eight mass flow rates per speed. Static and total pressures were measured at the inlet and outlet of the stage. Static pressure distributions were mapped on the vaneless diffuser and volute casings. These data evaluates the characteristics of these components after the modifications.

scholarly journals Optimal Modulation Techniques of a DAB Based Isolated Bidirectional Single-stage Single-phase AC-DC Converter

2021 ◽  
Author(s):  
Dibakar Das ◽  
Kaushik Basu ◽  
Sayan Paul
Keyword(s):  
High Frequency ◽  
Power Flow ◽  
Degrees Of Freedom ◽  
Single Phase ◽  
Single Stage ◽  
Switching Frequency ◽  
Switching Loss ◽  
Two Stage ◽  
Wide Range ◽  
Bidirectional Power Flow

A bidirectional single-phase AC to DC converter with high-frequency isolation finds a wide range of applications, including charging electric vehicles in the vehicle to grid applications. A conventional two-stage solution, where an AC-DC front-end rectifier is connected to an isolated DC-DC converter, suffers from poor efficiency due to hard switching of the AC-DC stage and poor reliability due to the existence of an electrolytic capacitance at the interstage DC link. A Dual Active Bridge (DAB) based single-stage AC-DC converter with a potential of bidirectional power flow can overcome the problems of a two stage solution. A rich literature exists in search for finding an efficient modulation strategy for this converter. This paper presents two constant switching frequency modulation strategies that support bidirectional power flow at any power factor utilizing all three degrees of freedom in modulation, also known as triple phase-shift modulation (TPS). One of the strategies minimizes RMS high-frequency transformer current over the line cycle, and the other one optimizes peak current. Hence, the conduction loss and the component stress over the entire line cycle are minimized. ZVS conditions are met for all high-frequency switching devices for the whole operating region, while the AC side converter is line frequency switched, incurring negligible switching loss. AC line current waveforms are of high quality and free from low-frequency harmonics. UPF operation is of importance for single-phase power conversion. All possible modes that the converter will experience over a line cycle for UPF operation are elaborated through detailed analysis. The proposed strategies are validated through experiment and simulation with 230 V, 50 Hz AC grid, 400 V DC, UPF, and output power of 1.2 kW.

scholarly journals A Transported Livengood-Wu Integral Model for Knock Prediction in CFD Simulation

2020 ◽  
Author(s):  
Zongyu Yue ◽  
Chao Xu ◽  
Sibendu Som ◽  
C. Scott Sluder ◽  
K. Dean Edwards ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Single Stage ◽  
Integral Model ◽  
Two Stage ◽  
Modeling Approach ◽  
Oscillation Analysis ◽  
Auto Ignition ◽  
Wide Range

Abstract This work describes the development of a transported Livengood-Wu (L-W) integral model for computational fluid dynamics (CFD) simulation to predict auto-ignition and engine knock tendency. The currently employed L-W integral model considers both single-stage and two-stage ignition processes, thus can be generally applied to different fuels such as paraffin, olefin, aromatics and alcohol. The model implementation is first validated in simulations of homogeneous charge compression ignition combustion for three different fuels, showing good accuracy in prediction of auto-ignition timing for fuels with either single-stage or two-stage ignition characteristics. Then, the L-W integral model is coupled with G-equation model to indicate end-gas auto-ignition and knock tendency in CFD simulations of a direct-injection spark-ignition engine. This modeling approach is about 10 times more efficient than the ones that based on detailed chemistry calculation and pressure oscillation analysis. Two fuels with same Research Octane Number (RON) but different octane sensitivity are studied, namely Co-Optima Alkylate and Co-Optima E30. Feed-forward neural network model in conjunction with multi-variable minimization technique is used to generate fuel surrogates with targets of matched RON, octane sensitivity and ethanol content. The CFD model is validated against experimental data in terms of pressure traces and heat release rate for both fuels under a wide range of operating conditions. The knock tendency — indicated by the fuel energy contained in the auto-ignited region — of the two fuels at different load conditions correlates well with the experimental results and the fuel octane sensitivity, implying the current knock modeling approach can capture the octane sensitivity effect and can be applied to further investigation on composition of octane sensitivity.

A Transported Livengood-Wu Integral Model for Knock Prediction in CFD Simulation

2021 ◽  
Author(s):  
Zongyu Yue ◽  
Chao Xu ◽  
Sibendu Som ◽  
Charles Scott Sluder ◽  
K. Dean Edwards ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Single Stage ◽  
Integral Model ◽  
Two Stage ◽  
Modeling Approach ◽  
Oscillation Analysis ◽  
Auto Ignition ◽  
Wide Range

Abstract This work describes the development of a transported Livengood-Wu (L-W) integral model for computational fluid dynamics (CFD) simulation to predict auto-ignition and engine knock tendency. The currently employed L-W integral model considers both single-stage and two-stage ignition processes, thus can be generally applied to paraffin, olefin, aromatics and alcohol. The model implementation is first validated in simulations of homogeneous charge compression ignition combustion for three different fuels, showing good accuracy in prediction of auto-ignition timing for fuels with either single-stage or two-stage ignition characteristics. Then, the L-W integral model is coupled with G-equation model to indicate end-gas auto-ignition and knock tendency in CFD simulations of a direct-injection spark-ignition engine. This modeling approach is about 10 times more efficient than the ones that based on detailed chemistry calculation and pressure oscillation analysis. Two fuels with same Research Octane Number but different octane sensitivity are studied, namely Co-Optima Alkylate and Co-Optima E30. The CFD model is validated against experimental data in terms of pressure traces and heat release rate for both fuels under a wide range of operating conditions. The knock tendency-indicated by fuel energy contained in the auto-ignited region-of the two fuels at different load conditions correlates well with the experimental results and the fuel octane sensitivity, implying the current knock modeling approach can capture the octane sensitivity effect and can be applied to further investigation on composition of octane sensitivity.

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