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RISS 인기검색어
- 검색키워드
- 저자 : Deyou Li (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Influence of axial clearance on the performance characteristics of a turbopump
Deyou Li,Zhipeng Ren,Rong Fan,Yafei Chai,Ruzhi Gong,Hongjie Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10
To evaluate the influence of axial clearance on the performance characteristics in turbopumps, numerical simulations of an entire flow passage were carried out. The simulations were validated by performance characteristic experiments. The progress of the reciprocating axial movement in the rotor between the front and back covers was disassembled into five fixed clearances groups. Hump characteristic occurs at the same flow rate under these clearances groups. The hydraulic loss of the inducer-impeller was clearly influenced by the clearances. In particular, the hydraulic loss of the impeller changes significantly at the low flow rate under the ±0.3 mm clearance. With the increase of the flow rate, the effect of the clearance change on the flow is weakened. An innovative entropy production analysis was also performed. The distribution of the high local entropy production rate at the impeller inlet under the 0 mm clearance and at the impeller outlet under the −0.15 mm and −0.3 mm clearances overlapped with the vortex caused by flow separation, and the counterpart at the back cover is concentrated around the clearance structures, thereby leading to high hydraulic loss.
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Influence of Guide Vane Setting in Pump Mode on Performance Characteristics of a Pump-Turbine
Li, Deyou,Wang, Hongjie,Nielsen, Torbjorn K.,Gong, Ruzhi,Wei, Xianzhu,Qin, Daqing Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.2
Performance characteristics in pump mode of pump-turbines are vital for the safe and effective operation of pumped storage power plants. However, the head characteristics are different under different guide vane openings. In this paper, 3-D steady simulations were performed under 13mm, 19mm and 25mm guide vane openings. Three groups of operating points under the three GVOs were chosen based on experimental validation to investigate the influence of guide vane setting on flow patterns upstream and downstream. The results reveal that, the guide vane setting will obviously change the flow pattern downstream, which in turn influences the flow upstream. It shows a strong effect on hydraulic loss (power dissipation) in the guide and stay vanes. It is also found that the hydraulic loss mainly comes from the flow separation and vortices. In addition, in some operating conditions, the change of guide vane opening will change the flow angle at the runner inlet and outlet, which will change the Euler momentum (power input). The joint action of Euler momentum and hydraulic loss results in the change of the head characteristics.
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Influence of Guide Vane Setting in Pump Mode on Performance Characteristics of a Pump-Turbine
Deyou Li,Hongjie Wang,Torbjørn K. Nielsen,Ruzhi Gong,Xianzhu Wei,Daqing Qin 한국유체기계학회 2017 International journal of fluid machinery and syste Vol.10 No.2
Performance characteristics in pump mode of pump-turbines are vital for the safe and effective operation of pumped storage power plants. However, the head characteristics are different under different guide vane openings. In this paper, 3-D steady simulations were performed under 13mm, 19mm and 25mm guide vane openings. Three groups of operating points under the three GVOs were chosen based on experimental validation to investigate the influence of guide vane setting on flow patterns upstream and downstream. The results reveal that, the guide vane setting will obviously change the flow pattern downstream, which in turn influences the flow upstream. It shows a strong effect on hydraulic loss (power dissipation) in the guide and stay vanes. It is also found that the hydraulic loss mainly comes from the flow separation and vortices. In addition, in some operating conditions, the change of guide vane opening will change the flow angle at the runner inlet and outlet, which will change the Euler momentum (power input). The joint action of Euler momentum and hydraulic loss results in the change of the head characteristics.
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Analysis of vorticity dynamics for hump characteristics of a pump turbine model
Deyou Li,Ruzhi Gong,Hongjie Wang,Lei Han,Xianzhu Wei,Daqing Qin 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.8
Conventional parameters based on CFD methodology for the investigation on hump characteristics of a pump turbine cannot reflect the dynamic interaction mechanism between the runner and the fluid. This research presents a dynamic interaction mechanism of a pump turbine operating in the hump region. First, vorticity dynamic parameters were obtained based on the theory of vorticity dynamics. Second, 3-D unsteady flow simulations were performed in a full pump turbine model using the SST k-ω turbulence model, and numerical results have a good agreement with the experiments. Then, analysis was carried out to determine the relation between the vorticity dynamic parameters and hump characteristics. The results indicate that the theory of vorticity dynamics has an advantage in evaluating the dynamic performance of a pump turbine. The energy transfer between the runner and the fluid is through vorticity dynamic parameterspressure and friction terms, in which the pressure term accounts for the most. Furthermore, vortex generation mainly results from the skin friction. Combining vorticity dynamic analysis with the method of Q-criterion indicates that hump characteristics are related to the reduction of the surface normal pressure work and vortex motion on the suction surfaces close to the leading edges in the runner, and the increase of skin friction work in the stay-guide vanes.
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Analysis of transient flow in a pump-turbine during the load rejection process
Xiaolong Fu,Deyou Li,Hongjie Wang,Guanghui Zhang,Zhenggui Li,Xianzhu Wei 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5
The transient flow in pump-turbines during the load rejection process is very complex. However, few studies have been conducted on three-dimensional (3-D) numerical simulation. Hence, we simulated 3-D transient turbulent flow in a pump-turbine during the load rejection process using the calculation method of coupling the flow with the rotor motion of rigid body. To simulate the unsteady boundary conditions, the dynamic closing process of the guide vanes was simulated with the dynamic mesh technology. The boundary conditions at the spiral-casing inlet and the draft tube outlet were determined using the user defined functions (UDF) according to the experimental data. The numerical results of the rotational speeds show a good agreement with the experimental data. Then, the complex transient flow in the pump-turbine during the load rejection process was analyzed based on the numerical results. The results show that there are severe unsteady vortex flows in the vaneless space near the conditions under which the hydraulic torque on the runner equals to zero. When the pump-turbine operates into the maximum reverse discharge condition in the reverse pump operating process, the unsteady vortex flows in the vaneless space are instantaneously impacted into the region between the guide vanes and the stay vanes by the sudden reverse flows. The formation and development mechanism of the unsteady vortex flow in the vaneless space is associated with the distribution characteristic of the velocity field.
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