Numerical 3D Simulation of the Cavitating Flow in a Centrifugal Pump With Low Specific Speed and Evaluation of the Suction Head

2014 ◽  
Author(s):  
Phillip Limbach ◽  
Marius Kimoto ◽  
Christian Deimel ◽  
Romuald Skoda
Keyword(s):  
Centrifugal Pump ◽  
Single Phase ◽  
Cavitating Flow ◽  
Model Parameters ◽  
Pump Efficiency ◽  
Phase Flow ◽  
Flow Conditions ◽  
Single Phase Flow ◽  
Low Specific Speed ◽  
Specific Speed

A numerical analysis is performed to assess the capability of common simulation methods, in particular Ansys CFX, to predict the performance and NPSH curve of a centrifugal pump at very low specific speed for both, design and off-design conditions. In all cases, we use an entire numerical model containing the impeller, the volute casing, the side chambers as well as suction pipe and pressure pipe. A three-dimensional setup is used, testing the following numerical models: steady, i.e. frozen rotor model, unsteady model accounting for the impeller movement and the relative impeller-volute position, single-phase flow as well as cavitating flow conditions. The global performance of the pump is assessed in terms of pressure head, power consumption and pump efficiency for single-phase flow. Furthermore, the drop of the pump head and Net Positive Suction Head (NPSH) characteristics are analyzed for cavitating flow conditions. Numerical results are validated against experimental data. Regarding non-cavitating flow conditions, the trend of the characteristic curves is well predicted, while absolute performance values differ from measured data significantly. The results of steady and unsteady calculations deviate from each other by less than 2%. Concerning cavitating flow, unsteady simulations have to be performed in particular for overload conditions, in order to obtain convergence of the solver. The trend of the measured NPSH curve is well captured with default cavitation model parameters. For nominal and overload, the predicted NPSH curve underestimates the measured one significantly.

Aluminium scrap melting under different liquid aluminium flow conditions: part-I: single phase flow

2016 ◽  
Vol 55 (3) ◽  
pp. 261-272 ◽  
Author(s):  
S. A. Argyropoulos ◽  
Z. Li ◽  
M. Sukhram ◽  
M. Bussmann ◽  
D. Doutre
Keyword(s):  
Single Phase ◽  
Phase Flow ◽  
Flow Conditions ◽  
Single Phase Flow ◽  
Liquid Aluminium ◽  
Scrap Melting

Numerical and Experimental Analysis of Cavitating Flow in a Low Specific Speed Centrifugal Pump With Different Surface Roughness

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Phillip Limbach ◽  
Romuald Skoda
Keyword(s):  
Surface Roughness ◽  
Centrifugal Pump ◽  
Three Dimensional ◽  
Computational Effort ◽  
Cavitating Flow ◽  
Wall Functions ◽  
Operation Conditions ◽  
Low Specific Speed ◽  
Specific Speed ◽  
The Cost

Three-dimensional (3D) simulations with ansys cfx 16.1 as well as measurements of the cavitating flow in a low specific speed centrifugal pump (nq = 12 min−1) are performed for different operation conditions and varying surface roughness. Surface roughness is considered by wall functions in the flow simulations. Good agreement between measured and calculated head is achieved for noncavitating flow. Net positive suction head (NPSH3%) rises toward overload due to incidence, flow separation, and vapor zones at the volute tongue. The NPSH3% rise is slightly higher for rough walls according to measurements and significantly overestimated by the wall function approach, irrespective of the roughness level in the simulation. A low-Reynolds number approach at the volute tongue leads to a more accurate prediction of NPSH3% than wall functions, at the cost of high computational effort.

A Study Involving the Flow Pattern Comparison of a PIV Experiment With CFD Simulation, for the Flow Within a Centrifugal Pump

2014 ◽  
Author(s):  
Md. Taifur Rahman ◽  
Mohammed Siddiqi
Keyword(s):  
Centrifugal Pump ◽  
Single Phase ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Test Subject ◽  
Cfd Modeling ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Turbo Machinery ◽  
Multi Phase

Computational Fluid Dynamics (CFD) modeling software is increasingly being used as the tool of choice for analyzing the flow details and integrated performance of turbo-machinery products. In fact, the use of CFD is rapidly transitioning from a verification tool to an upfront design-enabling & optimization tool. Experimental validation of computational simulation is essential to ensure an acceptable degree of reliability and relevance of the simulated results to real world performance. While CFD has been rigorously validated for numerous simple physics cases like single-phase flow, more complex physics applications, e.g., those involving multi-phase solid-liquid flows, require more elaborate and thoughtful means of validation. In this context, a study was undertaken to review Particle Image Velocimetry (PIV) as a means of validating more complex CFD cases and to contrast the findings with those obtained from CFD simulation. PIV offers a new possibility for flow visualization in turbo-machinery passages, in contrast to traditional methods like flow probing or hot-wire anemometry, which can be a very challenging proposition in the rotating domain of a turbo-machinery blade system. This paper discusses the first phase of this work, which was limited to single-phase flow studies, with the intent to follow up further with multi-phase flow studies. A specially designed fractional horsepower centrifugal pump is used as a test subject to analyze all possible parameters of the flow field using PIV and the result is then compared with the CFD simulations of the same model. The results show a reasonable match in the flow patterns obtained by the two alternate methods, although significant differences are apparent too. In conclusion, each method has its own place in the context of turbo-machinery flow studies.

scholarly journals Effect of Short Blade Circumferential Position Arrangement on Gas-Liquid Two-Phase Flow Performance of Centrifugal Pump

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1317
Author(s):  
Biaobiao Wang ◽  
Haoyang Zhang ◽  
Fanjie Deng ◽  
Chenguang Wang ◽  
Qiaorui Si
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Low Flow ◽  
Phase Flow ◽  
Centrifugal Pumps ◽  
Suction Surface ◽  
Two Phase ◽  
Low Specific Speed ◽  
Specific Speed

In order to study the internal flow characteristics of centrifugal pumps with a split impeller under gas-liquid mixed transportation conditions, this paper conducted a steady calculation of the flow field in the centrifugal pump under the conditions of different inlet gas volume fractions based on the Eulerian-Eulerian heterogeneous flow model, using air and water as the working media and the Schiller Nauman model for the interphase resistance. This paper takes a low specific speed centrifugal pump as the research object, through the controlling variables, using the same pump body structure and pump body geometric parameters and setting three different arrangements of long and short blades (each plan uses the same long and short blades) to explore the influence of the short blade arrangement on the low specific speed centrifugal pump performance under a gas-liquid two-phase flow. The research results show that, under pure water conditions, the reasonable arrangement of the short blade circumferential position can eliminate the hump of the centrifugal pump under low-flow conditions, can make the flow velocity in the impeller more uniform, and can optimize the performance of the pump. Under the design conditions and the gas-liquid two-phase inflow conditions, when the circumferential position of the short blades is close to the suction surface of the long blades, some of the bubbles on the suction surface of the long blade can be broken under the work of the pressure surface of the short blade and flow out of the impeller with the liquid, which improves the flow state of the flow field in the impeller.

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