Effects of distance between impeller and guide vane on losses in a low head pump by entropy production analysis

Pei, Ji; Meng, Fan; Li, Yanjun; Yuan, Shouqi; Cai, Jia

doi:10.1177/1687814016679568

Cited by 54 publications

(27 citation statements)

References 21 publications

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“…Pei et al. 17 evaluated the effects of the distance between guide vane and impeller on the internal flow loss distribution and overall power loss in a low head pump through KED analysis. The results show that the efficiency of low head pump is considerably affected by the distance under a positive rotation condition.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of energy loss in a centrifugal pump through kinetic energy dissipation theory

Lai

Zhu

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this study, energy loss within a centrifugal pump is investigated by post-processing three-dimensional unsteady flow field through kinetic energy dissipation theory. The three-dimensional unsteady flow field is predicted by solving unsteady Reynolds-averaged Navier–Stokes equations. The kinetic energy dissipation consists of three parts: averaged kinetic energy dissipation, turbulent kinetic energy dissipation, and near-wall revised kinetic energy dissipation. The total value variations of three kinetic energy dissipations in the centrifugal pump with flowrate are investigated and compared. Results show that with the increase in flowrate, the total near-wall revised kinetic energy dissipation gradually increases, the total turbulent kinetic energy dissipation first gradually decreases and then gradually increases, and reaches the minimum value at the design flowrate. The total averaged kinetic energy dissipation is less than the total turbulent and the total near-wall revised kinetic energy dissipations, and the total near-wall revised kinetic energy dissipation is larger than the total turbulent kinetic energy dissipation when the flowrate is larger than 0.75 Qdes. The space variation of the near-wall revised kinetic energy dissipation with flowrate shows that large near-wall revised kinetic energy dissipation mainly occurs at the volute and transfers from the small cross-section casing to large cross-section casing and discharge pipe with the increase in flowrate. The space variations of the turbulent kinetic energy dissipation with time for three flowrates are also discussed. Results indicate that large turbulent kinetic energy dissipation near the volute tongue evidently changes with the rotation of the impeller, particularly in 0.5 Qdes. The large turbulent kinetic energy dissipation gradually expands to the pressure side of the blade when the volute tongue gradually approaches the middle of the impeller blade passage. The large turbulent kinetic energy dissipation transfers from the impeller inlet and outlet to the volute tongue and discharge pipe with the increase in flowrate. The findings of this study can serve as guide to improve the design of centrifugal pumps.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of energy loss in a centrifugal pump through kinetic energy dissipation theory

Lai

Zhu

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Pei et al. 23 took the entropy production method to evaluate the effect of distance on internal flow loss distribution and obtained better understanding of hydraulic loss mechanism. Thus, entropy production is better in reporting loss distribution than hydraulic efficiency or total pressure loss coefficient.…”

Section: Introductionmentioning

confidence: 99%

Optimal hydraulic design of an ultra-low specific speed centrifugal pump based on the local entropy production theory

Hou

Zhang

Zhou

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part A:

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The ultra-low specific speed centrifugal pump has been widely applied in aerospace engineering, metallurgy, and other industrial fields. However, its hydraulic design lacks specialized theory and method. Moreover, the impeller and volute are designed separately without considering their coupling effect. Therefore, the optimal design is proposed in this study based on the local entropy production theory. Four geometrical parameters are selected to establish orthogonal design schemes including blade outlet setting angle, wrapping angle volute inlet width, and throat area. Subsequently, a 3D steady flow with Reynolds stress turbulent model and energy equation model is numerically conducted and the entropy production is calculated by a user-defined function code. The range analysis is made to identify the optimal scheme indicating that the combination of local entropy production and orthogonal design is feasible on pump optimization. The optimal pump is visibly improved with an increase of 1.08% in efficiency. Entropy production is decreased by 16.75% and 6.03% in impeller and volute, respectively. High energy loss areas are captured and explained in terms of helical vortex and wall friction, and the turbulent and wall entropy production are respectively reduced by 3.82% and 14.34% for the total pump.

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“…These high entropy generation rates occurred at the interface of the cavity, especially for the rear part of the cavity region. Pei et al [7] studied the effects of the distance between the guide vane and impeller on the mechanical energy dissipation and distributions of this dissipation in a low-head pump applying the entropy generation method. They found that the distance affects the efficiency of the pump under positive rotation conditions and that the main mechanical energy dissipation is turbulent dissipation.…”

Section: Introductionmentioning

confidence: 99%

“…The above studies adopting the entropy generation method to investigate mechanical energy dissipation [4][5][6][7][8][9] were conducted for turbines or centrifugal pumps. Meanwhile, the main focus of our research is the exact magnitudes and distributions of mechanical energy dissipation under varying discharge and tip clearance using the entropy generation method near the hump region for an axial-flow pump.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis of Mechanical Energy Dissipation for an Axial-Flow Pump Based on Entropy Generation Theory

Shen

2019

Energies

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Mechanical energy dissipation is a major problem affecting hydraulic machinery especially under partial-load conditions. Owing to limitations of traditional methods in evaluating mechanical energy dissipation, entropy generation theory is introduced to study mechanical energy dissipation with varying discharge and tip clearance intuitively through numerical simulations in an axial-flow pump. Results show that the impeller and diffuser are the main domains of mechanical energy dissipation, respectively accounting for 35.32%–55.51% and 32.61%–20.42% of mechanical energy dissipation throughout the flow passage. The mechanical energy dissipation of the impeller has a strong relation with the hump characteristic and becomes increasingly important with decreasing discharge. Areas of high turbulent dissipation in the impeller are mainly concentrated near the blades’ suction sides, and these regions, especially areas near the shroud, extend with decreasing discharge. When the pump enters the hump region, the distributions of turbulent dissipation near the shroud become disordered and expand towards the impeller’s inlet side. Unstable flows, like flow separation and vortices, near the blades’ suction sides lead to the high turbulent dissipation in the impeller and hump characteristic. Turbulent dissipation at the tip decreases from the blade leading edge to trailing edge, and regions of high dissipation distribute near the leading edge of the blade tip side. An increase in tip clearance for the same discharge mainly increases areas of high turbulent dissipation near the shroud and at the tip of the impeller, finally reducing pump performance.

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Effects of distance between impeller and guide vane on losses in a low head pump by entropy production analysis

Cited by 54 publications

References 21 publications

Numerical investigation of energy loss in a centrifugal pump through kinetic energy dissipation theory

Numerical investigation of energy loss in a centrifugal pump through kinetic energy dissipation theory

Optimal hydraulic design of an ultra-low specific speed centrifugal pump based on the local entropy production theory

Numerical Analysis of Mechanical Energy Dissipation for an Axial-Flow Pump Based on Entropy Generation Theory

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