Numerical Simulation of Internal Flow in Stamping and Welding Multistage Centrifugal Pump

2011 ◽  
Vol 291-294 ◽  
pp. 2608-2611 ◽  
Author(s):  
Yuan Yi Liu ◽  
Rui Guang Li ◽  
Kai Sun
Keyword(s):  
Centrifugal Pump ◽  
Function Method ◽  
Reference Model ◽  
Internal Flow ◽  
Flow Regulation ◽  
The Other ◽  
Wall Function ◽  
Multistage Centrifugal Pump ◽  
Multistage Pump ◽  
Multiple Reference

Based on the Reynolds time-averaged N-S equations and standard k-ε two-equation turbulent mode, using multiple reference model and wall function method, the inner flow fields were simulated which is a part of three different kinds of impeller on stamping and welding multistage centrifugal pump by CFD software FLUENT. The characteristic of internal flow on multistage pump was analyzed base on the calculated results, so as to reveal how the flow regulation influences performance of pump. The result shows the internal flow condition in the distort-type impeller pump is more reasonable than the other two groups, there is not the flagrant whirlpool and the capability of cavitation-resistant is strong.

Numerical Investigation of the Influence of Impeller-Diffuser Gap (A- and B-Gaps) on Unsteady Flow in a Centrifugal Pump at Part Flows

2019 ◽  
Author(s):  
Taiki Takamine ◽  
Satoshi Watanabe
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Internal Flow ◽  
Leading Edge ◽  
High Energy ◽  
Rotating Stall ◽  
Rotor System ◽  
The Other ◽  
High Energy Density

Abstract Because of the high energy density of multi-stage centrifugal pump, it is really important to ensure the reliability of the pumps thus the stability of rotor system in the wide flow rate range. Rotating stall is a well-known unsteady flow phenomenon in which one or several stall cell structures propagate circumferentially in impeller and/or diffuser. Rotating stall alters the peripheral pressure distribution of rotors, and therefore it is often regarded as one of the primary trigger of unstable fluid force acting on the rotor system. One possible factor which could affect the rotating stall is a geometrical relationship between the rotor and the stator. In the present study, unsteady RANS simulations of internal flow in a centrifugal pump are carried out. The pump is the partial model of the final stage of the three-stage centrifugal pump used in our previous study. In order to investigate the effect of the gap between impeller trailing edge and diffuser leading edge on the unsteady flow of the pump, three cases of impeller-diffuser gap is simulated; one is the smaller gap case with original impeller. The other cases are two larger gap cases with only cutting the impeller blades and with cutting the both impeller blades and impeller shroud walls. For all gap cases, the computations are conducted for the nominal flow rate and the low flor rate with 10% of the nominal flow rate. As a result, the rotating stall is observed only in the larger gap case with the cut shroud walls, indicating that the key phenomenon for the stable formation of the stall cell is not only the weakened rotor-stator interaction, but also the other phenomenon attributed to the enlarged gap between the impeller shroud walls and the diffuser walls. In the shroud cut case, a part of the main flow blocked by the stalled region and the secondary flow on the diffuser walls tend to flow into the side gaps more easily than other cases. They might be the important phenomenon associated with the diffuser rotating stall in the enlarged wall gap condition.

Unsteady Flow in the Vaned Diffuser of a Low Specific Speed Centrifugal Pump With an Unshrouded Impeller

2019 ◽  
Author(s):  
Asuma Ichinose ◽  
Tomoki Takeda ◽  
Kazuyoshi Miyagawa ◽  
Yohei Ogawa ◽  
Hideyo Negishi ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Internal Flow ◽  
The Other ◽  
Vaned Diffuser ◽  
Design Point ◽  
Other Hand ◽  
Impeller Outlet ◽  
Outlet Flow ◽  
Low Specific Speed ◽  
Specific Speed

Abstract The unsteady internal flow in a low specific speed centrifugal pump was experimentally and numerically investigated. Unshrouded impellers enable high head designs but on the other hand, they exhibit complicated internal flow and an efficiency decline compared to shrouded impellers. Furthermore, the complicated impeller outlet flow induces unsteady internal flow in the vaned diffuser. Therefore, a detailed investigation of the internal flow is required in order to increase the efficiency of these low specific speed centrifugal pumps. The aims of this paper are to clarify the loss mechanisms in the impeller and to investigate the effect of impeller outlet flow to the diffuser internal flow at the design point. The detailed pump internal flow is investigated using unsteady computation, which enables the computation of the 3D flow pattern. The reversed flow and the secondary flow are induced by the tip leakage flow, and this creates a high loss region in the blade-to-blade region. On the other hand, the mixing effect is remarkable at the impeller outlet, and this affects the creation of the wake. This flow behavior makes the internal flow of the diffuser unsteady and the diffuser performance fluctuates due to the impeller wake at the design point.

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 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 Investigation of Internal Flow in Centrifugal Pump Diffuser using Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics

2021 ◽  
Vol 1909 (1) ◽  
pp. 012075
Author(s):  
Daisuke Sugiyama ◽  
Asuma Ichinose ◽  
Tomoki Takeda ◽  
Kazuyoshi Miyagawa ◽  
Hideyo Negishi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Centrifugal Pump ◽  
Laser Doppler Velocimetry ◽  
Internal Flow ◽  
Laser Doppler ◽  
Doppler Velocimetry

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.

Experiment Study of the Internal Flow in Centrifugal Pump

2011 ◽  
Author(s):  
D. Liu ◽  
C. L. Wang ◽  
Jiachun Li ◽  
Song Fu
Keyword(s):  
Centrifugal Pump ◽  
Internal Flow ◽  
Experiment Study

scholarly journals Vertical and Horizontal Misfit Analysis of 3-unit FDP Fabricated with Different Techniques and CAD/CAM Systems

2018 ◽  
Vol 29 (4) ◽  
pp. 342-346
Author(s):  
Eduardo Piza Pellizzer1 ◽  
Caroline Cantieri de Mello ◽  
Jéssica Marcela de Luna Gomes ◽  
Joel Ferreira Santiago Júnior ◽  
Cleidiel Aparecido Araújo Lemos ◽  
...  
Keyword(s):  
Reference Model ◽  
Optical Microscope ◽  
The Other ◽  
Marginal Adaptation ◽  
Nicr Alloy ◽  
Partial Denture ◽  
Optical Scanning ◽  
Fixed Partial Denture ◽  
Cad Cam ◽  
Cam Systems

Abstract The aim of this is was evaluate the vertical and horizontal marginal adaptation of 3-unit fixed partial denture frameworks fabricated using different techniques and CAD/CAM systems. A total of 40 framework specimens were fabricated and divided into four groups as follows: lost-wax casting (G1); lost-wax casting with welding (G2); extraoral optical scanning of models (3S/DWOS) (G3); intraoral optical scanning (Cerec Bluecam/Sirona) (G4). A reference model was used to simulate a fixed partial denture with three elements (with a central pontic). The frameworks of G1 and G2 were cast in nickel-chromium (NiCr) alloy, whereas those of G3 and G4 were milled in zirconia. In all groups, vertical and horizontal marginal adaptation (over-contour and under-contour) was evaluated using a three-dimensional optical microscope (Quick Scope, Mitutoyo). The results showed higher vertical marginal misfit in G1 than in the other groups (p<0.001). Regarding horizontal marginal misfit, higher over-contour values occurred in G3 than in the other groups (p<0.001). G3 did not show under-contour at all, whereas the other groups did not differ from each other in this regard (p>0.05). Within the limitations of this study, it can be concluded that lost-wax casting with welding is a viable alternative to the use of CAD/CAM systems to fabricate frameworks of three-unit FPDs, since the techniques yielded similar vertical misfit values. Extra-oral CAD/CAM systems showed the highest horizontal misfit (over-contour) compared to other groups.

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