Three-Dimensional Simulation of Highly Unsteady and Isothermal Flow in Centrifugal Pumps for the Local Loss Analysis Including a Wall Function for Entropy Production

Melzer, Steffen; Pesch, Andreas; Schepeler, Stephan; Kalkkuhl, Tobias; Skoda, Romuald

doi:10.1115/1.4047967

Cited by 17 publications

(6 citation statements)

References 24 publications

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“…The definition of LHLR can be expressed as equation (13). And for the hydraulic loss in wall region, entropy wall functions proposed by Melzer et al 40 is adapted. The hydraulic loss in wall region can be expressed as equation (16), of which Ttrues˙pro,wall,normalD¯ and Ttrues˙pro,wall,normalD′ are mean flow part and turbulent part, respectively.…”

Section: Resultsmentioning

confidence: 99%

Optimization on high-pressure side of pump-turbine runner based on high efficiency and stability criterion via multi-objective genetic algorithm method

Qin

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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Pumped storage power plants are doomed to play a more important role in peak-valley shifting hence the demand for operation stability is gradually regarded as an equal important criterion as high efficiency. In our paper, new concepts, namely “swept,” “bowed (lean),” and “twisted” are introduced to systematic innovative design the geometry of high-pressure side (HPS) of a pump-turbine runner. Thereafter, a multi-objective optimization process, which consists of design of experiment (DoE), meta model generation, multi-objective genetic algorithm (MOGA), self-organization map (SOM) and takes both high efficiency and stability discipline into account is produced. The final optimization plan is selected and testified numerically. Compared to the original runner, the efficiency is improved from 91.7% to 91.9% at pump mode and improved from 92.3% to 92.8% at turbine mode. Moreover, the S margin is increased from 89.34° to 90.23° at small GVO and increased from 79.56° to 80.29° at large GVO. Besides, hump unsteady region is completely eliminated. Moreover, the flow characteristic comparation is conducted based on local hydraulic loss rate (LHLR) method. For design points, the optimized runner obviously decreases the hydraulic loss in hub and middle part of runner domain for turbine mode and slightly decrease the hydraulic loss in stay vane region for pump mode. For unsteady characteristics, HPS can better adjust the hydraulic loss distribution in corresponding discharge operating points, largely decreasing S unsteady characteristic in turbine mode and eliminating hump unsteady characteristic in pump mode. We believe that the methods proposed in our paper can bring the design of hydraulic machinery to a new level.

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Section: Resultsmentioning

confidence: 99%

Optimization on high-pressure side of pump-turbine runner based on high efficiency and stability criterion via multi-objective genetic algorithm method

Qin

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…As a result, hydraulic losses previously calculated using the entropy production theory were much lower than those calculated using the differential pressure method. Melzer changed the original form of the entropy wall function, and finally obtained the dimensionless entropy wall function in the mean flow state and turbulent state, as shown in Equations ( 7) and (8) [37]: , it is necessary to integrate the neighboring cells of the wall and then average through the characteristic lengths. For this study, we chose the first layer of the wall boundary layer mesh y + 1 and the center of the mesh y + as the integration length and feature length.…”

Section: Entropy Wall Functionmentioning

confidence: 99%

The Splitter Blade Pump–Turbine in Pump Mode: The Hump Characteristic and Hysteresis Effect Flow Mechanism

Dong,

Luo,

Guo

et al. 2024

Processes

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This study focuses on the splitter blade pump–turbine as the research object to analyze the problems of hump characteristics and the hysteresis effect. We simulated the operation of the pump condition with small opening of the guide vane, analyzed the hydraulic loss by using the entropy production theory and entropy wall function, and investigated the study of internal flow transfer characteristics. In this paper, it was first verified that the maximum error of the energy loss calculated by the pressure method and the entropy production method was less than 6% for the working zone. From the quantified energy loss results, a significant instability feature was observed in the 0.65 QBEP–0.9 QBEP operating interval, accompanied by the phenomenon of the non-overlapping of the characteristic curves. The results show that the hump characteristic with hysteresis effect also exists in the splitter blade pump–turbine. The percentage of energy loss in the hump zone is in descending order of runner, guide vanes, spiral casing, and draft tube, but this changes again at low flow rates. By analyzing the high-entropy production region, it was found that the high-hydraulic-loss region is mainly distributed at the trailing edge of the long blade in the vane-less space, which is different from the traditional runner.

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“…Flow loss in pump is mainly the internal flow loss induced by fluid motion. Many scholars [20][21][22][23][24] have studied the connection between the flow loss and hydraulic performance of centrifugal pump, mixed flow pump and other types of pumps in detail. However, the research on the flow loss of slanted axial-flow pump under different working conditions is not enough.…”

Section: Introductionmentioning

confidence: 99%

Analysis of flow loss characteristics of slanted axial-flow pump device based on entropy production theory

Yang

et al. 2022

R. Soc. open sci.

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Slanted axial-flow pump devices are widely applied in urban water supply, irrigation and drainage engineering fields. The second law of thermodynamics is applied to investigate the flow loss characteristics of the 30° slanted axial-flow pump model according to the flow loss analysis method of entropy production theory, so that the hydraulic loss characteristics can be revealed in internal flow process of the slanted axial-flow pump. The three-dimensional numerical simulation of the whole flow conduit in slanted axial-flow pump was conducted and the entropy production increased in the flow process was calculated. The location and distribution characteristics of the flow loss of the pump were qualitatively analysed. The results show that the entropy production in impeller is the highest among the pump components. With the increase of flow rate, the proportion of the entropy production in impeller in total value of the pump device increases continuously. The wall entropy production of impeller, guide vane and outlet conduit are lower than the mainstream entropy production, and the mainstream entropy production occupies the dominant position. As the flow rate grows, the proportion of turbulent dissipation entropy production decreases, and the proportion of wall dissipation entropy production increases. At 0.8 Q bep , the proportion of turbulent dissipation entropy production is close to 74%, which is about 2.8 times that of wall entropy production. Under 1.2 Q bep condition, the proportion of turbulent dissipation entropy production is just 5.5% higher than that of wall dissipation entropy production.

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Three-Dimensional Simulation of Highly Unsteady and Isothermal Flow in Centrifugal Pumps for the Local Loss Analysis Including a Wall Function for Entropy Production

Cited by 17 publications

References 24 publications

Optimization on high-pressure side of pump-turbine runner based on high efficiency and stability criterion via multi-objective genetic algorithm method

Optimization on high-pressure side of pump-turbine runner based on high efficiency and stability criterion via multi-objective genetic algorithm method

The Splitter Blade Pump–Turbine in Pump Mode: The Hump Characteristic and Hysteresis Effect Flow Mechanism

Analysis of flow loss characteristics of slanted axial-flow pump device based on entropy production theory

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