Numerical and Experimental Investigations in a Vaned Diffuser of SHF Impeller: Fluid Leakage Effect (original) (raw)
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FLUID LEAKAGE EFFECT ON ANALYSIS OF A VANED DIFFUSER OF SHF PUMP
The paper presents the results of numerical analysis on the local and global internal flow behaviour at the inlet of the vaned diffuser of a radial flow pump model, taking into account the effect of fluid leakages for various flow rates and a given rotation of speed. For each flow rate, numerical calculations were performed both with two different boundary conditions: -Without any leakage effects. -With calculated leakage effects The numerical simulations were realized with the two commercial codes: i-Star CCM+ 8.02.011 (at LML), ii-CFX 10.0 (at University of Padova). RANS unsteady calculations, with a k- RNG model were performed with Star CCM+. Fully unsteady calculations of the whole pump were done with CFX with DES turbulentmethod (Cavazzini [1]). For each flow rate, different angular positions of the impeller are considered. First part of the paper shows global comparisons between numerical and experimental results already presented in ref [2-3], for which the effects of fluid ...
Investigations inside a vaned diffuser of a centrifugal pump at low flowrates
IOP conference series, 2016
This paper focuses on the unsteady flow behaviour inside the vaned diffuser of a radial flow pump model, operating at partial flowrates (0.387Q i , 0.584Q i and 0.766Q i where Q i is the impeller design flowrate).The effects of the leakage flows are taken into account in the analysis. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given speed of rotation, for several flowrates and different angular impeller positions. The performances and the static pressure rise of the diffuser were also measured using a three-holes probe in the same experimental conditions. The unsteady numerical simulations were carried out with Star CCM+ 10.02 code with and without leakage flow. The PIV measurements showed a high unsteadiness at very low flowrate which was confirmed by the numerical calculations. In previous studies it has been shown that the global performances, as the efficiencies are in good agreement between calculations and measurements. In this paper, a joint analysis of measurements and numerical calculations is proposed to improve the understanding of the flow behaviour in a vaned diffuser. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
IOP Conference Series: Earth and Environmental Science, 2019
The realization and the validation of a simulation in fluid mechanics require an indepth expertise of the modelling process. However, how could the results be guaranteed if they were not accompanied by experimental measurements? On the other hand experimental measurements show some limitations. For example, PIV measurements are limited to certain viewing planes and rarely near the walls. Moreover, this type of results rarely represents instantaneous results but rather a temporal average of the flows over the measurement time. The use of measurement probes is an intrusive method that can modify the flow and which, as the previous method leads to a mean time result. The purpose of this paper is to analyse the experimental results of the SHF pump which have already been the subject of numerous publications by using the results of the CFD which were made with the computing code star CCM +. This paper includes the comparisons between calculations and measurements inside the diffuser which makes possible to comment on the usefulness and the validity of the stationary measurements despite the unsteady nature of the flow. The analysis highlights the influence of leak rates at the entrance of the diffuser and shows a significant influence of these leak rates on the creation of recirculation swirls that disturb the flow at the entrance of some diffuser channels.
Numerical and experimental investigations in a vaned diffuser of SHF impeller
HAL (Le Centre pour la Communication Scientifique Directe), 2013
Le papier présente l'analyse des performances et de l'écoulement interne dans un diffuseur aubé d'une pompe centrifuge grâce à la technique PIV, aux sondes de pression et aux simulations numériques. Les mesures PIV ont été réalisées à différentes hauteurs dans un canal du diffuseur, pour une vitesse de rotation et différents débits. Dans chaque cas, les mesures PIV ont été effectuées pour différentes positions angulaires de la roue. Des sondes de pression trois trous ont également été utilisées dans le diffuseur à différentes positions radiales et axiales. Les simulations numériques ont été réalisées avec deux codes: i-Star CCM+ 7.02.011 (LML), ii-CFX 10.0 (Université de Padoue). Des comparaisons entre résultats numériques (modélisation instationnaire) et expérimentaux sont présentés et discutés pour deux débits. Les effets des pertes dues aux jeux entre parties fixes et partie tournante sont étudiés.
2017
The paper refers to the analysis of interactions between the impeller and the vaned diffuser of a radial flow pump tested in air. The vaned diffuser comes with two configurations: channel type and cascade type. The study deals with unsteady numerical simulations of the flow for complete 3D geometries of impeller and vaned diffusers in order to capture the full interaction effects. The task is conducted close to design operating conditions. The results focus on the flow pattern at the outlet part inside the impeller and influence from the diffuser vanes. Results from both diffuser configurations are compared and discussed. Results are also compared with the available PIV measurements.
FLUID LEAKAGE EFFECT ON ANALYSIS OF A VANED DIFFUSER OF SHF
The paper presents the results of numerical analysis on the local and global internal flow behaviour at the inlet of the vaned diffuser of a radial flow pump model, taking into account the effect of fluid leakages for various flow rates and a given rotation of speed. For each flow rate, numerical calculations were performed both with two different boundary conditions: - Without any leakage effects - With calculated leakage effects. The numerical simulations were realized with the two commercial codes: i-Star CCM+ 8.02.011 (at LML), ii-CFX 10.0 (at University of Padova). RANS unsteady calculations, with a k- RNG model were performed with Star CCM+. Fully unsteady calculations of the whole pump were done with CFX with DES turbulent method. For each flow rate, different angular positions of the impeller are considered. First part of the paper shows global comparisons between numerical and experimental results already presented in the lecterature, for which the effects of fluid leakage due to the gap between the rotating and fixed part of the pump model were found to be interesting to be analysed. Second part is devoted to the local comparisons of flow structures at the inlet section of the diffuser, without and with leakages only with Star CCM+.
WSEAS TRANSACTIONS ON FLUID MECHANICS
The article presents the analysis of the interactions between the impeller and the vaned diffuser of a radial flow pump. The tests were carried out on the so-called SHF impeller, coupled with a vaned diffuser, and working with air. The particularity of this machine is that the diffuser design flow rate corresponds to 80% of the impeller one. All experimental works were performed at the Fluid Mechanics Laboratory in ENSAM, Lille, France. Investigations have been made for five different flow rates. Global performances of the machine are evaluated thanks to pressure measurements and averaged velocities obtain with a three hole probe, at nine angular positions at diffuser inlet and outlet just as five radial positions in a middle section of a blade-to-blade passage. A post-processing procedure, based on statistical tools, was applied to the experimental results in order to reach a better understanding of the phenomena. In another approach, a numerical simulation of the flow inside the p...
La Houille Blanche, 2015
The paper presents the analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV (particles image velocimetry) technique, pressure probe traverses and numerical simulations. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given rotational speed and various flow rates. For each operating condition, PIV measurements have been made for different angular positions of the impeller. Probe traverses have also been performed using a 3 holes pressure probe from hub to shroud diffuser width at different radial locations in between the two diffuser geometrical throats. The numerical simulations were realized with the two commercial codes: i-Star CCM+ 8.02.011 (RANS (Reynolds Averaged Navier Stokes) turbulence model, frozen rotor and unsteady calculations), ii-CFX 10.0 (turbulence modelled with DES model (Detached Eddy Simulation) combining RANS with LES (Large Eddy Simulation), unsteady calculations). Comparisons between numerical (fully unsteady calculations) and experimental results are presented and discussed for two flow rates. In this respect, the effects of fluid leakage due to the gap between the rotating and fixed part of the pump model are analysed and discussed.
ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D, 2011
PIV measurements were performed at mid hub to shroud section inside the impeller of a vaned diffuser pump model working with air. The measurements were restricted to the outlet section of the impeller where the diffuser blades interacted with the impeller flow. Each PIV measuring plane was related to one particular impeller blade to blade channel and analysed according to different relative positions of the vaned diffuser. Two frame change models were considered: the so-called frozen rotor approach for different impeller passage positions relative to the vaned diffuser and a fully unsteady calculation of the whole pump. Comparisons between numerical and experimental results are presented and discussed for a specific mass flow rate corresponding to an off-design point for the impeller and a design point for the vaned diffuser.