Flow Physics Leading to System Instability in a Centrifugal Pump

1994 ◽  
Vol 116 (4) ◽  
pp. 612-620 ◽  
Author(s):  
A. M. Wo ◽  
J. P. Bons
Keyword(s):  
Centrifugal Pump ◽  
Flow Separation ◽  
Side Wall ◽  
Outer Side ◽  
Pump Operation ◽  
Design Performance ◽  
Flow Recirculation ◽  
Pumping System ◽  
Region Flow ◽  
Flow Features

The off-design performance in a centrifugal pump is investigated experimentally. The objective is to identify flow features that lead to the onset of surge as the fundamental pumping system instability. Results show that there are primarily two reasons for the onset of surge as the flow is reduced in the pump studied: (a) adverse flow in the tongue region, and (b) destabilizing effect of the pipe diffuser. The former is due to premature diffusion of the flow entering the tongue region, which is manifested by increased flow recirculation through the tongue/impeller gap and flow separation on the volute outer side-wall opposite the tongue. These effects in the tongue region flow coupled with the destabilizing behavior of the pipe diffuser lead to the eventual unstable pump operation.

Flow Physics Leading to System Instability in a Centrifugal Pump

1993 ◽  
Author(s):  
Andrew M. Wo ◽  
Jeffrey P. Bons
Keyword(s):  
Centrifugal Pump ◽  
Flow Separation ◽  
Side Wall ◽  
Outer Side ◽  
Pump Operation ◽  
Design Performance ◽  
Flow Recirculation ◽  
Pumping System ◽  
Region Flow ◽  
Flow Features

The off-design performance in a centrifugal pump is investigated experimentally. The objective is to identify flow features which lead to the onset of surge as the fundamental pumping system instability. Results show that there are primarily two reasons for the onset of surge as the flow is reduced in the pump studied: (a) adverse flow in the tongue region and (b) destabilizing effect of the pipe diffuser. The former is due to premature diffusion of the flow entering the tongue region, which is manifested by increased flow recirculation through the tongue/impeller gap and flow separation on the volute outer side-wall opposite the tongue. These effects in the tongue region flow coupled with the destabilizing behavior of the pipe diffuser lead to the eventual unstable pump operation.

Aero-Thermal Investigation of a Rib-Roughened Trailing Edge Channel With Crossing-Jets: Part I—Flow Field Analysis

2008 ◽  
Author(s):  
Alessandro Armellini ◽  
Filippo Coletti ◽  
Tony Arts ◽  
Christophe Scholtes
Keyword(s):  
Flow Field ◽  
Computational Study ◽  
Three Dimensional ◽  
Side Wall ◽  
Field Analysis ◽  
Trailing Edge ◽  
Present Contribution ◽  
Numerical Predictions ◽  
Flow Features ◽  
Rib Roughened

The present contribution addresses the aero-thermal experimental and computational study of a trapezoidal cross-section model simulating a trailing edge cooling cavity with one rib-roughened wall. The flow is fed through tilted slots on one side wall and exits through straight slots on the opposite side wall. The flow field aerodynamics is investigated in part I of the paper. The reference Reynolds number is defined at the entrance of the test section and set at 67500 for all the experiments. A qualitative flow model is deduced from surface-streamline flow visualizations. Two-dimensional Particle Image Velocimetry measurements are performed in several planes around mid-span of the channel and recombined to visualize and quantify three-dimensional flow features. The jets issued from the tilted slots are characterized and the jet-rib interaction is analyzed. Attention is drawn to the motion of the flow deflected by the rib-roughened wall and impinging on the opposite smooth wall. The experimental results are compared with the numerical predictions obtained from the finite volume, RANS solver CEDRE.

Characterization of Cavitation During Pump Operation Based on Hilbert-Huang Transform

2018 ◽  
Author(s):  
Hui Sun ◽  
Shouqi Yuan ◽  
Yin Luo ◽  
Bo Gong
Keyword(s):  
Centrifugal Pump ◽  
Longitudinal Vibration ◽  
Process Time ◽  
Current Signal ◽  
Vibration Signals ◽  
Pump Operation ◽  
Hilbert Huang Transform ◽  
Time Frequency ◽  
Cavitation Process ◽  
Non Stationary Signal

Cavitation has negative influence on pump operation. In order to detect incipient cavitation effectively, experimental investigation was conducted to through acquisition of current and vibration signals during cavitation process. In this research, a centrifugal pump was modeled for research. The data was analyzed by HHT method. The results show that Torque oscillation resulted from unsteady flow during cavitation process could result in energy variation. Variation regulation of RMS of IMF in current signal is similar to that in axial vibration signal. But RMS of IMF in current signal is more sensitive to cavitation generation. It could be regarded as the indicator of incipient cavitation. RMS variation of IMF in base, radial, longitudinal vibration signals experiences an obvious increasing when cavitation gets severe. Such single variation regulation could be selected as the indicator of cavitation stage recognition. Hilbert-Huang transform is suitable for transient and non-stationary signal process. Time-frequency characteristics could be extracted from results of HHT process to reveal pump operation condition. The contents of current work could provide valuable references for further research on centrifugal pump operation detection.

Fluid Particle Motion and Lagrangian Velocities for Pulsatile Flow Through a Femoral Artery Branch Model

1987 ◽  
Vol 109 (1) ◽  
pp. 94-101 ◽  
Author(s):  
M. R. Back ◽  
Y. I. Cho ◽  
D. W. Crawford ◽  
L. H. Back
Keyword(s):  
Femoral Artery ◽  
Flow Separation ◽  
Pulsatile Flow ◽  
Reverse Flow ◽  
Branch Model ◽  
Flow Features ◽  
Flow Phase ◽  
Flow Through ◽  
Artery Flow ◽  
Artery Branch

A flow visualization study using selective dye injection and frame by frame analysis of a movie provided qualitative and quantitative data on the motion of marked fluid particles in a 60 degree artery branch model for simulation of physiological femoral artery flow. Physical flow features observed included jetting of the branch flow into the main lumen during the brief reverse flow period, flow separation along the main lumen wall during the near zero flow phase of diastole when the core flow was in the downstream direction, and inference of flow separation conditions along the wall opposite the branch later in systole at higher branch flow ratios. There were many similarities between dye particle motions in pulsatile flow and the comparative steady flow observations.

Numerical Analysis of the Deterministic Stresses Associated to Impeller-Tongue Interactions in a Single Volute Centrifugal Pump

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
J. M. Fernández Oro ◽  
J. González ◽  
R. Barrio Perotti ◽  
M. Galdo Vega
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Centrifugal Pump ◽  
Turbulence Intensity ◽  
Three Dimensional ◽  
Relevant Information ◽  
Three Dimensional Flow ◽  
Deterministic Analysis ◽  
Starting Point ◽  
Flow Features

In this paper, a deterministic stress decomposition is applied over the numerical three-dimensional flow solution available for a single volute centrifugal pump. The numerical model has proven in previous publications its robustness to obtain the impeller to volute-tongue flow interaction, and it is now used as starting point for the current research. The main objective has been oriented toward a detailed analysis of the lack of uniformity in the flow that the volute tongue promotes on the blade-to-blade axisymmetric pattern. Through this analysis, the fluctuation field may be retrieved and main interaction sources have been pinpointed. The results obtained with the deterministic analysis become of paramount interest to understand the different flow features found in a typical centrifugal pump as a function of the flow rate. Moreover, this postprocessing tool provides an economic and easy procedure for designers to compare the different deterministic terms, also giving relevant information on the unresolved turbulence intensity scales. Complementarily, a way to model the turbulent effects in a systematic way is also presented, comparing their impact on the performance with respect to deterministic sources in a useful framework, that may be applied for similar kinds of pumps.

A Method to Optimize the Operation of Pumping System

2009 ◽  
Author(s):  
Chao Liu
Keyword(s):  
Electric Power ◽  
Cooling System ◽  
Operation Performance ◽  
Power Cost ◽  
Pump Operation ◽  
Fundamental Factor ◽  
Pumping System ◽  
Long Time ◽  
Operation Cost ◽  
Modeling Equation

There are many pumps working in generating plant for pumping water in the cooling system. The pumps consume a big amount of electricity especially in large generating plant which operates continuously for long time. Therefore, the electric power cost will increase with increasing of operation cost of the pumping system. It is very important to minimize the operation cost of the pumping system to optimize the use of generating plant assets. In order to optimize the operation of pumping system the method of adjusting pump rotation speeds are often adopted. The fundamental factor of optimizing pump operation is to obtain the operation performance. Theoretically the affinity law (special modeling Equation) of pumps can be applied to convert the performances of pumps under rated speeds to variable rotation speeds. However the affinity law can only be applied in the region of pump operation around Best Efficiency Point with an acceptable precision. Also the affinity law derived from the Modeling Equation can only be valid to pump or pump bowl rather than pumping system. In this paper a method was conducted to determine the performances of pumping system based on the computational and experimental results. The principle of optimizing the pumping system is discussed. Finally the optimizing operation alternative of the pumping system is presented.

scholarly journals Analysis of the reasons of double suction centrifugal pump’s failure

Mechanik ◽  
2017 ◽  
Vol 90 (11) ◽  
pp. 1084-1087
Author(s):  
Witold Lorenz ◽  
Marcin Janczak
Keyword(s):  
Centrifugal Pump ◽  
Vibration Level ◽  
Flow Conditions ◽  
Pump Operation ◽  
Design Solutions

The issue of a pump operation beyond its recommended range and required flow conditions to the suction flange and consequently failure of double suction axially split centrifugal pump was explained. The increased vibration level, improper configuration of the suction pipeline and used hydraulics were presented. It was also illustrated how to diagnose and solve a problem which after implementation at the target workplace has confirmed the correctness of implemented design solutions.

scholarly journals Study of Dual Stator Induction Motor in Photovoltaic-Fuel Cell Hybrid Pumping Application

2020 ◽  
Vol 53 (5) ◽  
pp. 601-608
Author(s):  
Arezki Adjati ◽  
Toufik Rekioua ◽  
Djamila Rekioua ◽  
Abdelmounaim Tounzi
Keyword(s):  
Fuel Cell ◽  
Induction Motor ◽  
Centrifugal Pump ◽  
Cell Hybrid ◽  
Double Star ◽  
Water Requirements ◽  
Matlab Simulink ◽  
Pumping System ◽  
Dynamic Head

This paper discusses the modeling of hybrid Photovoltaic/Fuel cell pumping. This system comprises a photovoltaic generator and a fuel cell, two DC/DC converters, two of inverters which supply a double star induction motor (DSIM) which drives the shaft of a centrifugal pump. The evaluation of the water requirements, the total dynamic head (TDH) and the flow are of great importance to evaluate the various powers allowing the determination of the size of the pumping system. The global proposed system is sized and simulated under Matlab/Simulink Package. The obtained results under different metrological conditions show the effectiveness of the proposed hybrid pumping system.

Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump

2017 ◽  
Vol 231 (4) ◽  
pp. 290-302 ◽  
Author(s):  
Can Kang ◽  
Ning Mao ◽  
Chen Pan ◽  
Yang Zhu ◽  
Bing Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Low Flow ◽  
Back Surface ◽  
Flow Rates ◽  
Pump Operation ◽  
Low Specific Speed ◽  
Specific Speed

A low-specific-speed centrifugal pump equipped with long and short blades is studied. Emphasis is placed on the pump performance and inner flow characteristics at low flow rates. Each short blade is intentionally shifted towards the back surface of the neighboring long blade, and the outlet parts of the short blades are uniformly shortened. Unsteady numerical simulation is conducted to disclose inner flow patterns associated with the modified design. Thereby, a comparison is enabled between the two schemes featured by different short blades. Both practical operation data and numerical results support that the deviation and cutting of the short blades can eliminate the positive slope of pump head curve at low flow rates. Therefore, the modification of short blades improves the pump operation stability. Due to the shortening of the outlet parts of the short blades, velocity distributions between impeller outlet and radial diffuser inlet exhibit explicitly altered circumferential flow periodicity. Pressure fluctuations in the radial diffuser are complex in terms of diversified periodicity and amplitudes. Flow rate influences pressure fluctuations in the radial diffuser considerably. As flow rate decreases, the regularity of the orbit of hydraulic loads exerted upon the impeller collapses while hydraulic loads exerted upon the short blades remain circumferentially periodic.

Highly resolved experimental results of the separated flow in a channel with streamwise periodic constrictions

2016 ◽  
Vol 796 ◽  
pp. 257-284 ◽  
Author(s):  
Christian J. Kähler ◽  
Sven Scharnowski ◽  
Christian Cierpka
Keyword(s):  
Turbulent Flow ◽  
Flow Separation ◽  
Flow Direction ◽  
Separated Flow ◽  
Mean Flow ◽  
Complex Flow ◽  
Flow Measurements ◽  
Flow Features ◽  
Wall Flow ◽  
Near Wall

The understanding and accurate prediction of turbulent flow separation on smooth surfaces is still a challenging task because the separation and the reattachment locations are not fixed in space and time. Consequently, reliable experimental data are essential for the validation of numerical flow simulations and the characterization and analysis of the complex flow physics. However, the uncertainty of the existing near-wall flow measurements make a precise analysis of the near-wall flow features, such as separation/reattachment locations and other predicted near-wall flow features which are under debate, often impossible. Therefore, the periodic hill experiment at TU Munich (ERCOFTAC test case 81) was repeated using high resolution particle image velocimetry and particle tracking velocimetry. The results confirm the strong effect of the spatial resolution on the near-wall flow statistics. Furthermore, it is shown that statistically stable values of the turbulent flow variables can only be obtained for averaging times which are challenging to realize with highly resolved large eddy simulation and direct numerical simulation techniques. Additionally, the analysis implies that regions of correlated velocity fluctuations with rather uniform streamwise momentum exist in the flow. Their size in the mean flow direction can be larger than the hill spacing. The possible impact of the correlated turbulent motion on the wake region is discussed, as this interaction might be important for the understanding and control of the flow separation dynamics on smooth bodies.

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