Experiment and numerical simulation of cavitation performance for a double suction centrifugal pump

Based on two phase homogeneous mixture model, numerical simulation of the cavitating flow was performed on a centrifugal pump. Cavity shapes and performance of the pump in variable cavitation numbers were obtained. Numerical results show that the numerical method can be used to predict the cavitation performance of centrifugal pump; the incipient cavitation number is predicted, and the cavity shape is similar with the experiment; cavitation usually appears in the suction surface of the blade and locates in the inlet side, and becomes longer to the outlet direction with lower cavitation number; when the cavitation number is relatively higher, cavitating region locates in the inlet area of the blade and is relatively stable, while develops and separates when cavitation number becomes lower; when the cavitation number equals to the incipient cavitation number, performance of the centrifugal pump has no change almost, only when cavitation number reduces to some extent, the head decreases abruptly and also the efficiency, which means the pump operates in a bad condition and this condition should be avoided in the practical operation.

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Investigations on the effects of obstacles on the surfaces of blades of the centrifugal pump to suppress cavitation development

Modern Physics Letters B ◽

10.1142/s0217984921503279 ◽

2021 ◽

pp. 2150327

Author(s):

Weiguo Zhao ◽

Bao Guo

Keyword(s):

Numerical Simulation ◽

Kinetic Energy ◽

Centrifugal Pump ◽

Cavitation Flow ◽

Cavitation Model ◽

Cavitation Performance ◽

Simulation Results ◽

Specific Speed ◽

And Control ◽

Good Agreement

This paper proposes a new method that obstacles are attached to both the suction and pressure surfaces of the blades to suppress cavitation development. A centrifugal pump with a specific speed of 32 is selected as the physical model to perform the external characteristic and cavitation performance experiments. SST [Formula: see text] turbulence model and Zwart cavitation model were employed to simulate the unsteady cavitation flow in the pump. The results indicate that the numerical simulation results are in good agreement with the experimental counterparts. After the obstacles are arranged, the maximum head decrease is only 1.37%, and the relative maximum drop of efficiency is 1.12%. Obstacles have minimal impacts on the variations of head and efficiency under all flow rate conditions. The distribution of vapor volume in the centrifugal pump is significantly reduced after obstacles are arranged and the maximum fraction reduction is 53.6%. The amplitude of blade passing frequency decreases significantly. While obstacles decrease the intensity of turbulent kinetic energy near the wall in the impeller passages to effectively reduce the distribution of cavitation bubbles, and control the development of cavitation. After the obstacles are set, the strength of the vortex in the impeller passages is weakened significantly, the shedding of the vortex is suppressed, flow in the impeller becomes more stable.

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Theory and application of two-dimension viscous hydraulic design of the ultra-low specific-speed centrifugal pump

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650919850420 ◽

2019 ◽

Vol 234 (1) ◽

pp. 58-71 ◽

Cited By ~ 3

Author(s):

Cong Wang ◽

Yongxue Zhang ◽

Hucan Hou ◽

Zhiyi Yuan

Keyword(s):

Boundary Layer ◽

Centrifugal Pump ◽

Diagnostic Model ◽

Two Dimension ◽

Cavitation Performance ◽

Hydraulic Design ◽

Displacement Thickness ◽

Low Specific Speed ◽

Specific Speed ◽

Low Efficiency

Low efficiency and bad cavitation performance restrict the development of the ultra-low specific-speed centrifugal pump (ULSSCP). In this research, combined turbulent boundary layer theory with two-dimension design and two-dimension viscous hydraulic design method has been proposed to redesign a ULSSCP. Through the solution of the displacement thickness in the boundary layer, a less curved blade profile with a larger outlet angle was obtained. Then the hydraulic and cavitation performance of the reference pump and the designed pump were numerically studied. The comparison of performance of the reference pump calculated by the numerical and experimental results revealed a better agreement. Research shows that the average hydraulic efficiency and head of the designed pump improve by 2.9% and 3.3%, respectively. Besides, the designed pump has a better cavitation performance. Finally, through the internal flow analysis with entropy production diagnostic model, a 24.8% drop in head loss occurred in the designed pump.

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Influence of wall roughness on cavitation performance of centrifugal pump

Journal of the Brazilian Society of Mechanical Sciences and Engineering ◽

10.1007/s40430-021-03023-3 ◽

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.

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

Advances in Mechanical Engineering ◽

10.1177/1687814021998115 ◽

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.

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

Journal of Marine Science and Engineering ◽

10.3390/jmse9020121 ◽

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.

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