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

Yang, Fan; Li, Zhongbin; Hu, Wenzhu; Liu, Chao; Jiang, Dongjin; Li, Dongsheng; Nasr, Ahmed

doi:10.1098/rsos.211208

Cited by 27 publications

(26 citation statements)

References 35 publications

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“…Φ T is the entropy production due to dissipation increase and Φ θ T 2 is the entropy production caused by the heat transfer. Since the working medium inside the mixed-flow pump was set as constant temperature incompressible fluid [20,21], Φ T is the only source of entropy production inside the mixed-flow pump. In addition, the computational domain control equation is the Reynolds time-average equation, and hence the calculation formula of Φ T after time-averaged is as follows:…”

Section: Entropy Production Theorymentioning

confidence: 99%

“…The results show that the location of high hydraulic loss in the volute shifted from inlet to the baffle and tongue with the increase in flow rate. Yang [21] studied the distribution of entropy rate in guide vanes of an axial flow pump under different flow rates. He found that the area of high hydraulic losses decreased with increase in flow rate, but it increased with the shortening of the axial distance from the outlet.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of a Pumping Chamber on Hydraulic Losses in a Mixed-Flow Pump

et al. 2022

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In this study, entropy generation theory based on computational fluid dynamics (CFD) is used to study the influence of a pumping chamber type (guide vane and volute scheme) on the spatial distribution of hydraulic loss in a mixed-flow pump. The CFD data of the mixed-flow pump with a volute is validated by external characteristic test data under Q = 561.4–1598.6 m3/h. The results show that the efficiency and the head of the guide vanes scheme are lower under Q = 800–1200 m3/h, which resulted from a higher total entropy production (TEP) in the pumping chamber and outlet pipe. The high total entropy production rate (TEPR) inside the guide vanes can be found near the leading edge of the hub side and trailing edge of the rim side due to flow separation, which reduces the recovery efficiency of kinetic energy of the guide vanes. The high TEPR inside outlet pipe can be seen near the inlet, caused by back flow. However, the efficiency and head of the volute scheme are lower, under Q = 1200–1600 m3/h, owing to the fact that the volute cannot effectively convert kinetic energy into pressure energy and thus the high TEPR can be found near outlet of volute and inlet of outlet pipe. These results can provide useful suggestions to the matching optimization of the impeller and pumping chamber in a mixed-flow pump.

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Section: Entropy Production Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Influence of a Pumping Chamber on Hydraulic Losses in a Mixed-Flow Pump

et al. 2022

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“…The wall surface roughness scores of the inlet section, impeller, guide vanes, and outlet section were 0.05, 0.0125, 0.0125, and 0.05 mm, respectively. The interface between the stators was set as “None.” The interfaces between the rotor and stator for steady and unsteady calculations were set as “Stage” [ 29 ] and “Transient Rotor Stator” [ 30 ], respectively. In addition, the time step was 0.00037037 s, i.e., a rotation of 3° per time step [ 31 ].…”

Section: Numerical Simulationmentioning

confidence: 99%

“…The interface between the stators was set as "None." The interfaces between the rotor and stator for steady and unsteady calculations were set as "Stage" [29] and "Transient Rotor Stator" [30], respectively. In addition, the time step was 0.00037037 s, i.e., a rotation of 3 • per time step [31].…”

Section: Boundary Conditionmentioning

confidence: 99%

Energy Characteristics of a Bidirectional Axial-Flow Pump with Two Impeller Airfoils Based on Entropy Production Analysis

Meng

2022

Entropy

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This research sought to determine the spatial distribution of hydraulic losses for a bidirectional axial-flow pump with arc- and S-shaped impellers. The unsteady Reynolds time-averaged Stokes (URANS) approach with the SST k-omega model was used to predict the internal flow field. The total entropy production (TEP) and total entropy production rate (TEPR) were used to evaluate the overall and local hydraulic losses. The results show that the distribution of TEP and TEPR was similar for both impeller cases. Under a forward condition, TEP mainly comes from the impeller and elbow pipe. The high TEPR inside the impeller can be found near the shroud, and it shifts from the leading edge to the trailing edge with an increase in the flow rate due to the decline in the attack angle. The high TEPR inside the elbow pipe can be seen near the inlet, and the area shrinks with an increase in the flow rate caused by a reduction in the velocity circulation. Under the reverse condition, TEP mainly comes from the impeller and the straight pipe. The TEPR of the region near the shroud is obviously higher than for other regions, and the area of high TEPR near the suction side shrinks with an increase in the flow rate. The high TEPR of the straight pipe can be found near the inlet, and declines in the flow direction. These results provide a theoretical reference for future work to optimize the design of the bidirectional axial-flow pump.

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“…Under low-head operating conditions, axial flow pumps are more likely to exhibit good hydraulic performance characteristics. Hence, these pumps are suitable for largeand medium-sized pumping stations in plain areas, where they play a vital role in urban water supply and agricultural irrigation [1,2]. According to the installation position of the pump shaft, axial flow pumps can be classified into three types: vertical, horizontal, and slanted pumps.…”

Section: Introductionmentioning

confidence: 99%

Investigation into Influence of Wall Roughness on the Hydraulic Characteristics of an Axial Flow Pump as Turbine

et al. 2022

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Pump as turbine (PAT) is a factual alternative for electricity generation in rural and remote areas where insufficient or inconsistent water flows pose a threat to local energy demand satisfaction. Recent studies on PAT hydrodynamics have shown that its continuous operations lead to a progressive deterioration of inner surface smoothness, serving the source of near-wall turbulence build-up, which itself depends on the level of roughness. The associated boundary layer flow incites significant friction losses that eventually deteriorate the performance. In order to study the influence of wall roughness on PAT hydraulic performance under different working conditions, CFD simulation of the water flow through an axial-flow PAT has been performed with a RNG k-ε turbulence model. Study results have shown that wall roughness gradually decreases PAT’s head, efficiency, and shaft power. Nevertheless, the least wall roughness effect on PAT hydraulic performance was experienced under best efficiency point conditions. Wall roughness increase resulted in the decrease of axial velocity distribution uniformity and the increase of velocity-weighted average swirl angle. This led to a disorderly distribution of streamlines and backflow zones formation at the conduit outlet. Furthermore, the wall roughness impact on energy losses is due to the static pressure drop on the blade pressure surface and the increase of turbulent kinetic energy near the blade. Further studies on the roughness influence over wider range of PAT operating conditions are recommended, as they will lead to quicker equipment refurbishment.

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

Cited by 27 publications

References 35 publications

The Influence of a Pumping Chamber on Hydraulic Losses in a Mixed-Flow Pump

The Influence of a Pumping Chamber on Hydraulic Losses in a Mixed-Flow Pump

Energy Characteristics of a Bidirectional Axial-Flow Pump with Two Impeller Airfoils Based on Entropy Production Analysis

Investigation into Influence of Wall Roughness on the Hydraulic Characteristics of an Axial Flow Pump as Turbine

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