Unsteady flow in a viscous oil transporting centrifugal pump

2011 ◽  
Vol 1 (4) ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Acoustic Resonance ◽  
High Viscosity ◽  
Broadband Noise ◽  
Centrifugal Pumps ◽  
Viscous Oil ◽  
Flow Feature ◽  
Flow Variables ◽  
Ldv Measurement

AbstractAcoustic resonances are frequently fatal problems in centrifugal pump operations. Low pressure pulsation of fluid in the blade pass frequency is helpful to prevent from such problems. In addition, for a high quality centrifugal pump, a lower broadband noise level is also on demand. The acoustic resonance and broadband noise are associated with unsteadiness of flow in the pump. Even there exist extensive analyses of unsteady flow in centrifugal pumps by means of CFD so far, the effect of high viscosity of fluid pumped on the unsteadiness of flow feature remains unclear. Thus, the unsteady flow in an experimental centrifugal pump was exploited numerically when it transported the liquids with different viscosities. The velocity profiles at the impeller discharge were validated with the results of LDV measurement for water. The viscosity effect on the fluctuation of flow in the volute was clarified quantitatively. It was shown the increasing viscosity of fluid makes the fluctuation in flow variables less substantial and results into a less noticed tendency of separation of flow from the blade pressure side.

scholarly journals Numerical Study of Pressure Fluctuation and Unsteady Flow in a Centrifugal Pump

Processes ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 354 ◽  
Author(s):  
Ling Bai ◽  
Ling Zhou ◽  
Chen Han ◽  
Yong Zhu ◽  
Weidong Shi
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Flow Patterns ◽  
Lower Number ◽  
Centrifugal Pumps ◽  
Impeller Blade

A pump is one of the most important machines in the processes and flow systems. The operation of multistage centrifugal pumps could generate pressure fluctuations and instabilities that may be detrimental to the performance and integrity of the pump. In this paper, a numerical study of the influence of pressure fluctuations and unsteady flow patterns was undertaken in the pump flow channel of three configurations with different diffuser vane numbers. It was found that the amplitude of pressure fluctuation in the diffuser was increased gradually with the increase in number of diffuser vanes. The lower number of diffuser vanes was beneficial to obtain a weaker pressure fluctuation intensity. With the static pressure gradually increasing, the effects of impeller blade passing frequency attenuated gradually, and the effect of diffuser vanes was increased gradually.

Numerical Analysis of Unsteady Flow in Centrifugal Pumps With Impellers Based on Different Hydraulic Design Principles

2010 ◽  
Author(s):  
Jianping Yuan ◽  
Hongqin He ◽  
Zhixia He ◽  
Shouqi Yuan
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Design Method ◽  
Outlet Section ◽  
Centrifugal Pumps ◽  
Lower Efficiency ◽  
Fluctuation Phenomenon ◽  
Low Specific Speed ◽  
Specific Speed

The centrifugal pump is one of the most widely used pumps. Lower efficiency, worse cavitation performance and stronger unsteady flow are three main problems for the low-specific-speed centrifugal pumps. Due to unsteady flow within pumps, pressure is fluctuant, which further induces vibration and noise. For a centrifugal pump with different impellers, its characteristics of unsteady flow are also different. In this paper, five different impellers were designed adopting low-specific-speed design method, splitter-blades design method and velocity-coefficient method with a set of performance parameters (Q = 25m3/h, H = 10m, n = 1450r/min). 3D unsteady turbulent flow field within the centrifugal pump was simulated. The periodic fluctuation phenomenon and the unsteady flow characteristics were investigated. The static pressure fluctuation in the volute and at the volute outlet and the instantaneous head changes were showed for the pumps with five different impellers operated at design and off-design conditions. The pressure fluctuation is the strongest near the tongue and is slighter at the volute outlet section. The transient head fluctuation increases with the flow rate. The transient head fluctuation of the pump with the low-specific-speed designed impeller is the biggest, while that of the pump with the normal-designed impeller is the smallest. Among the three splitter-blade impellers, the transient head fluctuation of the impeller with splitter blades leaned to the corresponding suction side of the long blades is the smallest. Eventually, the different design schemes were evaluated using the unsteady flow analysis. These conclusions from this paper can supply some references for the design of low-specific-speed centrifugal pumps considering its pressure fluctuation and flow-induced vibration and noise.

Model of Flow in the Side Chambers of an Industrial Centrifugal Pump for Delivering Viscous Oil

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Wenguang Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Model ◽  
Rotating Disk ◽  
Mechanical Efficiency ◽  
High Viscosity ◽  
Experimental Results ◽  
Computational Method ◽  
Fluid Viscosity ◽  
Liquid Viscosity ◽  
Viscous Oil

A series of experiments has been conducted to identify the effects of both fluid viscosity and wear-rings gap on the performance of a low specific speed industrial centrifugal pump of type 65Y60 for transporting viscous oils by the author group. Unfortunately, the experimental results remained unexplained on a fluid dynamics base. To remedy this problem, a highly viscous oil flow model and computational method in the side chambers in that pump were proposed based on the existing theoretical and experimental results. The flow coupling between the chambers and the gaps of the wear-rings and/or the balance holes was realized. The model was validated by making use of the existing experiment data in the chamber between a rotating disk and the walls of a stationary cylindrical container. Then the flow model was applied into the two side chambers in that pump when the wear-rings clearances and liquid viscosity were changed. The results demonstrated that the flow model is sensitive to wear-rings gap, liquid viscosity, the roughness of the wet walls of the chambers, and leakage flow rate. For this pump, an enlarged clearance can improve the mechanical efficiency, but the increment in the efficiency is unable to compensate for the considerable drop in the volumetric efficiency, causing the gross efficiency not be improved, especially at a high viscosity.

scholarly journals Unsteady Flow and Pressure Pulsation Characteristics Analysis of Rotating Stall in Centrifugal Pumps Under Off-Design Conditions

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Xiaoran Zhao ◽  
Yexiang Xiao ◽  
Zhengwei Wang ◽  
Yongyao Luo ◽  
Lei Cao
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Flow Characteristics ◽  
Rotating Stall ◽  
Normal Operation ◽  
Centrifugal Pumps ◽  
Pressure Pulsations ◽  
Stall Cells ◽  
The Impact

Unsteady flow phenomena like rotating stall frequently occur in centrifugal pumps under off-design conditions. Rotating stall could lead to flow instabilities and pressure pulsation, which affect the normal operation of pumps. The mechanism of rotating stall has not been sufficiently understood in previous researches. In this study, the impact of rotating stall in the impeller on centrifugal pump stability and pressure pulsation is numerically investigated. This paper aims to detect the unsteady flow characteristics inside the centrifugal pump by computational fluid dynamics technology, to analyze pressure pulsations caused by rotating stall and to explore the propagation mechanism of rotating stall. Unsteady numerical simulations are performed by ANSYS 16.0 to model the unsteady flow within the entire flow passage of a centrifugal pump under 0.4QBEP and 0.6QBEP working conditions. Through flow characteristics research, the generation and propagation of rotating stall are discovered. Flow separation appears near the leading edge of the pressure side and transforms into vortices, which move along the passage. Meanwhile, the stall cells rotate circumferentially in the impeller. Additionally, frequencies and amplitudes of pressure pulsations related to rotating stall are investigated by spectrum analysis. The results detect a possible characteristic frequency of rotating stall and show that the interaction between stall cells and the volute tongue could have an influence on rotor–stator interaction (RSI).

Effect of semi-open impeller side clearance on centrifugal pump cavitation inception

2018 ◽  
Vol 1 (2) ◽  
pp. 24-39
Author(s):  
A. Farid ◽  
A. Abou El-Azm Aly ◽  
H. Abdallah
Keyword(s):  
Centrifugal Pump ◽  
Static Pressure ◽  
Rotation Speed ◽  
Centrifugal Pumps ◽  
Severe Condition ◽  
Cavitation Inception ◽  
Total Input ◽  
Input Pressure ◽  
Pump Head ◽  
Pump Pressure

Cavitation in pumps is the most severe condition that centrifugal pumps can work in and is leading to a loss in their performance.  Herein, the effect of semi-open centrifugal pump side clearance on the inception of pump cavitation has been investigated.  The input pump pressure has been changed from 80 to 16 kPa and the pump side clearance has been changed from 1 mm to 3 mm at a rotation speed of 1500 rpm. It has been shown that as the total input pressure decreased; the static pressure inside the impeller is reduced while the total pressure in streamwise direction has been reduced, also the pump head is constant with the reduction of the total input pressure until the cavitation is reached. Head is reduced due to cavitation inception; the head is reduced in the case of a closed impeller with a percent of 1.5% while it is reduced with a percent of 0.5% for pump side clearance of 1mm, both are at a pressure of 20 kPa.   Results also showed that the cavitation inception in the pump had been affected and delayed with the increase of the pump side clearance; the cavitation has been noticed to occur at approximate pressures of 20 kPa for side clearance of 1mm, 18 kPa for side clearances of 2mm and 16 kPa for 3mm.

scholarly journals Influence of wall roughness on cavitation performance of centrifugal pump

2021 ◽  
Vol 43 (6) ◽  
Author(s):  
Weihui Xu ◽  
Xiaoke He ◽  
Xiao Hou ◽  
Zhihao Huang ◽  
Weishu Wang
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Internal Flow ◽  
Wall Roughness ◽  
Blade Surface ◽  
Centrifugal Pumps ◽  
Three Dimensional Model ◽  
Cavitation Inception ◽  
Cavitation Performance ◽  
Critical Cavitation

AbstractCavitation is a phenomenon that occurs easily during rotation of fluid machinery and can decrease the performance of a pump, thereby resulting in damage to flow passage components. To study the influence of wall roughness on the cavitation performance of a centrifugal pump, a three-dimensional model of internal flow field of a centrifugal pump was constructed and a numerical simulation of cavitation in the flow field was conducted with ANSYS CFX software based on the Reynolds normalization group k-epsilon turbulence model and Zwart cavitation model. The cavitation can be further divided into four stages: cavitation inception, cavitation development, critical cavitation, and fracture cavitation. Influencing laws of wall roughness of the blade surface on the cavitation performance of a centrifugal pump were analyzed. Research results demonstrate that in the design process of centrifugal pumps, decreasing the wall roughness appropriately during the cavitation development and critical cavitation is important to effectively improve the cavitation performance of pumps. Moreover, a number of nucleation sites on the blade surface increase with the increase in wall roughness, thereby expanding the low-pressure area of the blade. Research conclusions can provide theoretical references to improve cavitation performance and optimize the structural design of the pump.

scholarly journals Design and Optimization of a Centrifugal Pump for Slurry Transport Using the Response Surface Method

Machines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 60
Author(s):  
Khaled Alawadhi ◽  
Bashar Alzuwayer ◽  
Tareq Ali Mohammad ◽  
Mohammad H. Buhemdi
Keyword(s):  
Response Surface ◽  
Centrifugal Pump ◽  
Industrial Applications ◽  
Pump Efficiency ◽  
Optimized Design ◽  
Centrifugal Pumps ◽  
Local Pressure ◽  
Design And Optimization ◽  
Geometry Characteristic ◽  
Line Design

Since centrifugal pumps consume a mammoth amount of energy in various industrial applications, their design and optimization are highly relevant to saving maximum energy and increasing the system’s efficiency. In the current investigation, a centrifugal pump has been designed and optimized. The study has been carried out for the specific application of transportation of slurry at a flow rate of 120 m3/hr to a head of 20 m. For the optimization process, a multi-objective genetic algorithm (MOGA) and response surface methodology (RSM) have been employed. The process is based on the mean line design of the pump. It utilizes six geometric parameters as design variables, i.e., number of vanes, inlet beta shroud, exit beta shroud, hub inlet blade draft, Rake angle, and the impeller’s rotational speed. The objective functions employed are pump power, hydraulic efficiency, volumetric efficiency, and pump efficiency. In this reference, five different software packages, i.e., ANSYS Vista, ANSYS DesignModeler, response surface optimization software, and ANSYS CFX, were coupled to achieve the optimized design of the pump geometry. Characteristic maps were generated using simulations conducted for 45 points. Additionally, erosion rate was predicted using 3-D numerical simulations under various conditions. Finally, the transient behavior of the pump, being the highlight of the study, was evaluated. Results suggest that the maximum fluctuation in the local pressure and stresses on the cases correspond to a phase angle of 0°–30° of the casing that in turn corresponds to the maximum erosion rates in the region.

scholarly journals Analysis of the Influence of Different Bionic Structures on the Noise Reduction Performance of the Centrifugal Pump

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 886
Author(s):  
Cui Dai ◽  
Chao Guo ◽  
Yiping Chen ◽  
Liang Dong ◽  
Houlin Liu
Keyword(s):  
Flow Field ◽  
Noise Reduction ◽  
Centrifugal Pump ◽  
Great Influence ◽  
Frequency Doubling ◽  
Sound Field ◽  
Internal Flow ◽  
Test System ◽  
Centrifugal Pumps ◽  
External Characteristics

The strong noise generated during the operation of the centrifugal pump harms the pump group and people. In order to decrease the noise of the centrifugal pump, a specific speed of 117.3 of the centrifugal pump is chosen as a research object. The bionic modification of centrifugal pump blades is carried out to explore the influence of different bionic structures on the noise reduction performance of centrifugal pumps. The internal flow field and internal sound field of bionic blades are studied by numerical calculation and test methods. The test is carried out on a closed pump test platform which includes external characteristics and a flow noise test system. The effects of two different bionic structures on the external characteristics, acoustic amplitude–frequency characteristics and flow field structure of a centrifugal pump, are analyzed. The results show that the pit structure has little influence on the external characteristic parameters, while the sawtooth structure has a relatively great influence. The noise reduction effect of the pit structure is aimed at the wide-band noise, while the sawtooth structure is aimed at the discrete noise of the blade-passing frequency (BPF) and its frequency doubling. The noise reduction ability of the sawtooth structure is not suitable for high-frequency bands.

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 Unsteady Flow and Structural Behaviors of Centrifugal Pump under Cavitation Conditions

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Denghao Wu ◽  
Yun Ren ◽  
Jiegang Mou ◽  
Yunqing Gu ◽  
Lanfang Jiang
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Structural Behaviors
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