Numerical Simulation and Evaluation of Velocity Fluctuations During Rotating Stall of a Centrifugal Pump

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Andreas Lucius ◽  
Gunther Brenner
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Local Variation ◽  
Rotating Stall ◽  
Flow Instabilities ◽  
Rotating Frame ◽  
Velocity Fluctuations ◽  
Fluid Forces ◽  
Stationary Frame ◽  
Simulation And Evaluation

Flow instabilities like rotating stall can lead to severe vibrations in turbomachines if the eigenfrequency of the rotor is equal to the stall frequency. The goal of the present work is to shed some light on the origin of the rotating stall phenomenon in a centrifugal pump. The resulting fluctuating loads are quantified using numerical computations. For the chosen configuration transient PIV data are available for validation. In addition to measuring the stall frequency in the stationary frame, the CFD data is analyzed in the rotating frame. A Fourier analysis is done for a large number of sample points. This enables us to determine the local variation of amplitudes for a given frequency. Together with eigenfrequencies and eigenmodes of the rotor determined from modal analysis, it is possible to evaluate the risk of resonance vibration excited from fluctuating fluid forces.

scholarly journals Detection of the Flow State for a Centrifugal Pump Based on Vibration

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3066 ◽  
Author(s):  
Jiaxing Lu ◽  
Xiaobing Liu ◽  
Yongzhong Zeng ◽  
Baoshan Zhu ◽  
Bo Hu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Great Influence ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Flow Instabilities ◽  
Flow State ◽  
Unstable Flow ◽  
Vibration Signals ◽  
State Identification ◽  
The Relationship

A combined numerical and experimental method study was performed to detect the inner flow state for a type of centrifugal pump. It was found that the inlet attack angles of blades in an impeller have a great influence on the flow instabilities in a centrifugal pump. The mechanism of the rotating stall in the impeller channel was explained. Meanwhile, flow state identification with vibration (FSIV) was proposed to detect the flow instabilities in a centrifugal pump. The relationship between the external vibration and the inner flow state has been established by FSIV. The characteristics and mechanism of the vibration produced by the flow instabilities in a centrifugal pump were investigated. It was found that the hump, the rotating stall, the backflow, the occurrence of unstable flow, and the cavitation in the centrifugal pump can be effectively detected by applying the vibration signals, which helps to obtain safe and steady operating conditions for the system.

scholarly journals Investigation of the Noise Induced by Unstable Flow in a Centrifugal Pump

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 589
Author(s):  
Jiaxing Lu ◽  
Xiaobing Liu ◽  
Yongzhong Zeng ◽  
Baoshan Zhu ◽  
Bo Hu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Frequency Band ◽  
Acoustic Pressure ◽  
Low Frequency ◽  
Internal Flow ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Flow Instabilities ◽  
Unstable Flow ◽  
Pump Inlet

In order to investigate the mechanism and the characteristics of the noise induced by unstable flow in a centrifugal pump, the internal flow characteristics in the pump were numerically researched, and the acoustic pressure fluctuations at the pump inlet and outlet were experimentally investigated. Obvious corresponding relationships between the flow instabilities, the cavitation and the noise were established. It was found that the rotating stall, the backflow, the hump, the occurrence of unstable flow and the cavitation in such a centrifugal pump were effectively detected through the noise, which could help to provide fundamental information on flow instabilities and guarantee safe and steady operating conditions for the system. The recirculation and prewhirl regions in the pump upstream pipe, which were caused by the backflow and the rotation of the impeller, presented the circumferential movement with a spiral shape, causing apparent broadband fluctuations at low frequency band of the acoustic pressure. The backflow and rotating stall could also result in broadband fluctuations of the pump outlet noise, which was distributed from 100 Hz to 150 Hz. Meanwhile, the broadband fluctuations of the pump outlet acoustic pressure distributed in the low frequency range, which was produced by the occurrence of cavitation, moved to the lower frequency band as the flow rate increased. The enhanced broadband fluctuations of the pump inlet and outlet noise distributed from 1 kHz to 6 kHz were caused by the coupling between the cavitation-induced noise and the system-produced noise. The broadband fluctuations of the pump inlet noise distributed between 6 kHz and 9 kHz were regarded as the typical frequency band of cavitation in the centrifugal pump.

scholarly journals Experiment and simulation about the effect of wear-ring abrasion on the performance of a marine centrifugal pump

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199811
Author(s):  
Wu Xianfang ◽  
Du Xinlai ◽  
Tan Minggao ◽  
Liu Houlin
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Velocity ◽  
Test Results ◽  
Obvious Effect ◽  
Performance Change ◽  
Pump Test ◽  
Simulation Results ◽  
Axis Passing

The wear-ring abrasion can cause performance degradation of the marine centrifugal pump. In order to study the effect of front and back wear-ring clearance on a pump, test and numerical simulation were used to investigate the performance change of a pump. The test results show that the head and efficiency of pump decrease by 3.56% and 9.62% respectively at 1.0 Qd due to the wear-ring abrasion. Under 1.0 Qd, with the increase of the front wear-ring the vibration velocity at pump foot increases from 0.4 mm/s to 1.0 mm/s. The axis passing frequency (APF) at the measuring points increases significantly and there appears new characteristic frequency of 3APF and 4APF. The numerical simulation results show that the front wear-ring abrasion affects the flow at the inlet of the front chamber of the pump and impeller passage. And the back wear-ring abrasion has obvious effect on the flow in the back chamber of the pump and impeller passage, while the multi-malfunction of the front wear-ring abrasion and back wear-ring abrasion has the most obvious effect on the flow velocity and flow stability inside pump. The pressure pulsation at Blade Passing Frequency (BPF) of the three schemes all decrease with the increase of the clearance.

scholarly journals Optimal Design of Slit Impeller for Low Specific Speed Centrifugal Pump Based on Orthogonal Test

2021 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Hongtao Zhou ◽  
Wanning Lv ◽  
Jian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Large Scale ◽  
Internal Flow ◽  
Orthogonal Test ◽  
Centrifugal Pumps ◽  
Initial Model ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Levels

Marine centrifugal pumps are mostly used on board ship, for transferring liquid from one point to another. Based on the combination of orthogonal testing and numerical simulation, this paper optimizes the structure of a drainage trough for a typical low-specific speed centrifugal pump, determines the priority of the various geometric factors of the drainage trough on the pump performance, and obtains the optimal impeller drainage trough scheme. The influence of drainage tank structure on the internal flow of a low-specific speed centrifugal pump is also analyzed. First, based on the experimental validation of the initial model, it is determined that the numerical simulation method used in this paper is highly accurate in predicting the performance of low-specific speed centrifugal pumps. Secondly, based on the three factors and four levels of the impeller drainage trough in the orthogonal test, the orthogonal test plan is determined and the orthogonal test results are analyzed. This work found that slit diameter and slit width have a large impact on the performance of low-specific speed centrifugal pumps, while long and short vane lap lengths have less impact. Finally, we compared the internal flow distribution between the initial model and the optimized model, and found that the slit structure could effectively reduce the pressure difference between the suction side and the pressure side of the blade. By weakening the large-scale vortex in the flow path and reducing the hydraulic losses, the drainage trough impellers obtained based on orthogonal tests can significantly improve the hydraulic efficiency of low-specific speed centrifugal pumps.

scholarly journals Numerical simulation and performance analysis of a four-stage centrifugal pump

2016 ◽  
Vol 8 (10) ◽  
pp. 168781401667375 ◽  
Author(s):  
Wei Li ◽  
Xiaoping Jiang ◽  
Qinglong Pang ◽  
Ling Zhou ◽  
Wei Wang
Keyword(s):  
Numerical Simulation ◽  
Performance Analysis ◽  
Centrifugal Pump ◽  
And Performance

Effects of Non-Axisymmetric Volute on Rotating Stall in the Vaneless Diffuser of a Centrifugal Compressor

2020 ◽  
Author(s):  
Zitian Niu ◽  
Zhenzhong Sun ◽  
Baotong Wang ◽  
Xinqian Zheng
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Centrifugal Compressor ◽  
Stability Boundary ◽  
Rotating Stall ◽  
Evolution Process ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Centrifugal Compressors ◽  
Specific Location

Abstract Rotating stall is an important unstable flow phenomenon that leads to performance degradation and limits the stability boundary in centrifugal compressors. The volute is one of the sources to induce the non-axisymmetric flow in a centrifugal compressor, which has an important effect on the performance of compressors. However, the influence of volute on rotating stall is not clear. Therefore, the effects of volute on rotating stall by experimental and numerical simulation have been explored in this paper. It’s shown that one rotating stall cell generates in a specific location and disappears in another specific location of the vaneless diffuser as a result of the distorted flow field caused by the volute. Also, the cells cannot stably rotate in a whole circle. The frequency related to rotating stall captured in the experiment is 43.9% of the impeller passing frequency (IPF), while it is 44.7% of IPF captured by three-dimensional unsteady numerical simulation, which proves the accuracy of the numerical method in this study. The numerical simulation further reveals that the stall cell initialized in a specific location can be split into several cells during the evolution process. The reason for this is that the blockage in the vaneless diffuser induced by rotating stall is weakened by the mainstream from the impeller exit to make one initialized cell disperse into several ones. The volute has an important influence on the generation and evolution process of the rotating stall cells of compressors. By optimizing volute geometry to reduce the distortion of the flow field, it is expected that rotating stall can be weakened or suppressed, which is helpful to widen the operating range of centrifugal compressors.

scholarly journals The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump

1992 ◽  
Author(s):  
A. Guinzburg ◽  
C. E. Brennen ◽  
A. J. Acosta ◽  
T. K. Caughey
Keyword(s):  
Centrifugal Pump ◽  
Guide Vane ◽  
Tangential Force ◽  
Inlet Guide Vane ◽  
Fluid Forces ◽  
Leakage Flows ◽  
Leakage Path ◽  
Inlet Swirl ◽  
Rotating Impeller ◽  
Rotordynamic Forces

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

Material Flow Estimation of Deep-Drawn Product by Using Finite-Element Simulation

2011 ◽  
Vol 301-303 ◽  
pp. 452-455 ◽  
Author(s):  
Yuji Kotani ◽  
Hisaki Watari ◽  
Akihiro Watanabe
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Finite Element Simulation ◽  
Material Flow ◽  
Thickness Distribution ◽  
Sheet Thickness ◽  
Original Material ◽  
Element Simulation ◽  
Thickness Prediction ◽  
Simulation And Evaluation

The approach to total weight reduction has been a key issue for car manufacturers as they cope with more and more stringent requirements for fuel economy. In sheet metal forming, local increases in product-sheet thickness effectively contribute to reducing the total product weight. Products could be designed more efficiently if a designer could predict and control the thickness distribution of formed products. This paper describes a numerical simulation and evaluation of the material flow in local thickness increments of products formed by an ironing process. In order to clarify the mechanism of the local increase in sheet thickness, a 3-D numerical simulation of deep drawing and ironing was performed using finite-element simulation. The effects of various types of finite elements that primarily affect thickness changes in original materials and thickness prediction were investigated. It was found that the sheet-thickness distribution could be predicted if the original material was relatively thick and if an appropriate type of finite element is selected.

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