Investigation of rotating stall characteristics in a centrifugal pump impeller at low flow rates

2017 ◽  
Vol 34 (6) ◽  
pp. 1989-2000 ◽  
Author(s):  
Peijian Zhou ◽  
Fujun Wang ◽  
Jiegang Mou
Keyword(s):  
Centrifugal Pump ◽  
Rotating Stall ◽  
Low Flow ◽  
Pump Impeller ◽  
Flow Rates ◽  
Content Type ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Stall Cells ◽  
Centrifugal Pump Impeller

Purpose Rotating stall is an unsteady flow phenomenon that causes instabilities and low efficiency in pumps. The purpose of this paper is to investigate the rotating stall characteristics and unsteady behavior of stall cells in a centrifugal pump impeller at low flow rates. Design/methodology/approach A developed large eddy simulation with dynamic mixed nonlinear model is performed to evaluate the unsteady flow in a centrifugal pump impeller. The rotating stall flow field through the centrifugal pump impeller is analyzed under three typical flow rates. Frequency spectrum analysis are carried out on the series of pressure fluctuation to get the rotating stall characteristics. The size and intensity of stall cells are also analyzed using time-averaged vorticity and static pressure. Findings The rotating stall cell first occurs in the suction side of the blade and exhibits an obvious life cycle including decay mergence, shedding, growing and development with a low frequency. With the decrease of flow rate, the amplitude of pressure fluctuations in the impeller tends to be larger, the propagated speed of stall cells and rotating stall frequency tends to be smaller, but the number of cells remains unchanged. The size of stall cells increases as the flow rate decreases, but intensity changes is very little. Originality/value The rotating stall characteristics in a centrifugal pump impeller under low flow rates are presented first using a developed large eddy simulation approach.

scholarly journals Large Eddy Simulation of Periodic Transient Pressure Fluctuation in a Centrifugal Pump Impeller at Low Flow Rate

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 311
Author(s):  
Renfei Kuang ◽  
Xiaoping Chen ◽  
Zhiming Zhang ◽  
Zuchao Zhu ◽  
Yu Li
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Low Frequency ◽  
Pump Impeller ◽  
Eddy Simulation ◽  
Inlet Flow Rate ◽  
Large Eddy ◽  
Centrifugal Pump Impeller

This paper presents a large eddy simulation of a centrifugal pump impeller during a transient condition. The flow rate is sinusoidal and oscillates between 0.25Qd (Qd indicates design load) and 0.75Qd when the rotating speed is maintained. Research shows that in one period, the inlet flow rate will twice reach 0.5Qd, and among the impeller of one moment is a stall state, but the other is a non-stall state. In the process of flow development, the evolution of low-frequency pressure fluctuation shows an obviously sinusoidal form, whose frequency is insensitive to the monitoring position and equals to that of the flow rate. However, inside the impeller, the phase and amplitude in the stall passages lag behind more and are stronger than that in the non-stall passages. Meanwhile, the strongest region of the high-frequency pressure fluctuation appears in the stall passages at the transient rising stage. The second dominant frequency in stall passages is 2.5 times to that in non-stall passages. In addition, similar to the pressure fluctuation, the evolution of the low-frequency head shows a sinusoidal form, whose phase is lagging behind that by one-third of a period in the inlet flow rate.

Flow in a Centrifugal Pump Impeller at Design and Off-Design Conditions—Part II: Large Eddy Simulations

2003 ◽  
Vol 125 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Rikke K. Byskov ◽  
Christian B. Jacobsen ◽  
Nicholas Pedersen
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Pump Impeller ◽  
Design Load ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Subgrid Scales ◽  
Centrifugal Pump Impeller

The flow field in a shrouded six-bladed centrifugal pump impeller has been investigated using large eddy simulation (LES). The effect of the subgrid scales has been modeled through a localized dynamic Smagorinsky model implemented in the commercial CFD code FINE/Turbo. A detailed analysis of the results of LES at design load, Q=Qd, and severe off-design conditions, at quarter-load Q=0.25Qd, is presented. At design load LES reveals a well-behaved flow field with no significant separation. At quarter-load significant differences between adjacent impeller passages are revealed. A steady nonrotating stall phenomenon is observed in the entrance of one passage and a relative eddy develops in the remaining part of the passage. The stall unblocks the adjacent passage which exhibits a flow dominated by rotational effects. Velocities predicted by LES and steady-state Reynolds averaged Navier-Stokes (RANS) simulations based on the Baldwin-Lomax and Chien k-ε turbulence models are compared with experimental data obtained from particle image velocimetry (PIV). The complex two-channel phenomena observed by LES is with satisfactory agreement confirmed by PIV. However, it is found that the two RANS models do not reproduce the stall phenomenon observed at quarterload and are incapable of detecting the differences between the two passages.

scholarly journals A Comparative Assessment of Spalart-Shur Rotation/Curvature Correction in RANS Simulations in a Centrifugal Pump Impeller

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ran Tao ◽  
Ruofu Xiao ◽  
Wei Yang ◽  
Fujun Wang
Keyword(s):  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Comparative Assessment ◽  
Turbulence Kinetic Energy ◽  
Low Flow ◽  
Pump Impeller ◽  
Curvature Correction ◽  
Centrifugal Pump Impeller ◽  
Low Flow Rate

RANS simulation is widely used in the flow prediction of centrifugal pumps. Influenced by impeller rotation and streamline curvature, the eddy viscosity models with turbulence isotropy assumption are not accurate enough. In this study, Spalart-Shur rotation/curvature correction was applied on the SSTk-ωturbulence model. The comparative assessment of the correction was proceeded in the simulations of a centrifugal pump impeller. CFD results were compared with existing PIV and LDV data under the design and low flow rate off-design conditions. Results show the improvements of the simulation especially in the situation that turbulence strongly produced due to undesirable flow structures. Under the design condition, more reasonable turbulence kinetic energy contour was captured after correction. Under the low flow rate off-design condition, the prediction of turbulence kinetic energy and velocity distributions became much more accurate when using the corrected model. So, the rotation/curvature correction was proved effective in this study. And, it is also proved acceptable and recommended to use in the engineering simulations of centrifugal pump impellers.

Investigation of rotating stall for a centrifugal pump impeller using various SGS models

2017 ◽  
Vol 29 (2) ◽  
pp. 235-242 ◽  
Author(s):  
Pei-jian Zhou ◽  
Fu-jun Wang ◽  
Zheng-jun Yang ◽  
Jie-gang Mou
Keyword(s):  
Centrifugal Pump ◽  
Rotating Stall ◽  
Pump Impeller ◽  
Centrifugal Pump Impeller

scholarly journals CFD simulation on centrifugal pump impeller with splitter blades

2020 ◽  
Vol 24 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Henrique M. P. Rosa ◽  
Bruno S. Emerick
Keyword(s):  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Computational Simulations ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Flow Rates ◽  
Computational Fluids Dynamics ◽  
Ansys Cfx ◽  
Computational Fluids ◽  
Centrifugal Pump Impeller

ABSTRACT The present paper aims to present the analysis and comparison of results of computational simulations using Computational Fluids Dynamics (CFD) in impellers of centrifugal pump. Three impellers were simulated: 1) original impeller, 2) original impeller with splitter blades at outlet; 3) original impeller with splitter blades at inlet. The splitters occupied 30% of the length of the main blades. They were simulated using the ANSYS-CFX software system in 1500 rpm rotational speed and at different flow rates. The turbulence model assumed was the Shear Stress Transport (SST). The results were used to build impeller blade head curves, besides the presentation of pressure distribution and streamline behaviour inside the impeller. It was verified that the insertion of the splitter blades reduced the impeller blade head, mainly the impeller with outlet splitter, whose reduction was more intense.

Comparative modeling and analysis of the flow asymmetricity in a centrifugal pump impeller at partial load

2019 ◽  
Vol 234 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Ran Tao ◽  
Zhengwei Wang
Keyword(s):  
Flow Regime ◽  
Centrifugal Pump ◽  
Channel Flow ◽  
Pressure Pulsation ◽  
Rotating Stall ◽  
Pressure Pulsations ◽  
Pump Impeller ◽  
Partial Load ◽  
Load Conditions ◽  
Centrifugal Pump Impeller

Undesirable flow regime occurs at partial-load conditions of the centrifugal pump. Flow separates at the leading edge and pulses in the blade channel with complex stall cell transfer law. The passing capability of the blade channel becomes important when rotating stall happens. In this study, the blade channel number influence on the flow stability in a centrifugal pump impeller was studied by unsteady flow simulations after numerical-experimental verification. The 5-, 6-, and 7-blade impellers were discussed under the same partial-load flow rate condition and the same rotating speed. Results show that the internal flow pattern was strongly influenced by the blade channel number. Periodic half-blockage was observed in the 5-blade impeller. Alternating stall with three stalled and three well-behaved channels existed in the 6-blade impeller. Complex aperiodic flow pattern occurred in the 7-blade impeller with the well-behaved, half-blocked, and fully stalled passages were all observed with stall cell transfer. The different flow regime caused different pressure pulsations. In the 5-blade impeller, the inter-channel flow frequencies, which were induced by the fluid extruded from blocked channels flowed into other channels, dominated. In the 6-blade impeller, the pressure pulsations performed low-in-amplitude and high-in-frequency. The flow regime was stable even under the rotating stall. In the 7-blade impeller, the rotating stall frequency dominated. The inter-channel flow frequencies were also obvious. The stable rotating stall pattern does not strongly influence the pressure pulsation and impeller axial and radial forces. The transferring stall cell induces extra mild pressure pulsation and impeller forces. The inter-channel flow adds strong pressure pulsation and impeller forces. When centrifugal pumps are operating at partial-load conditions, the flow characters especially the inter-channel flow caused by half-channel-blockage should be checked to avoid operation instability and security.

Measurements of Rotating Stall Inside a Centrifugal Pump Impeller

2005 ◽  
Author(s):  
D. A. Johnson ◽  
N. Pedersen ◽  
C. B. Jacobsen
Keyword(s):  
Centrifugal Pump ◽  
Marked Change ◽  
Rotating Stall ◽  
Velocity Measurements ◽  
Pump Impeller ◽  
Pressure Transducers ◽  
Design Load ◽  
Measured Flow ◽  
Flow Through ◽  
Centrifugal Pump Impeller

Velocity measurements have been obtained in a centrifugal pump with a volute. The measurements have been obtained between the blade passages of a shrouded impeller and in the volute region using laser Doppler velocimetry (LDV). Complimentary measurements have been obtained with pressure transducers circumferentially mounted on the volute. The flow through the impeller is measured at both design load and at several off-design conditions including severe off-design conditions. Results show that flow behaviour at design conditions Qd is well behaved. At reduced flow off-design conditions (0.25Qd) the measured flow pattern was altered significantly showing alternating stable stationary stalled and unstalled passages. Spectral analysis of the data from the LDV probe and the pressure probes showed a marked change in the spectrum as the stall phenomena occurs. This result is in contrast with previous researchers who have reported partially stalled flow passages or rotating stall conditions where the stall pattern rotated relative to the impeller with a regular frequency.

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