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Abstract

In this paper, the runaway transient process in a bulb turbine has been investigated by adopting commercial CFD code ANSYS CFX, and transient characteristics in the process have been examined and analyzed in detail. The results show that the predicted maximal runaway rotational speed and flow rate of the turbine are in close agreement with experimental data. During transient process, both the flow rate and rotational speed are rising with time, leading to an increase in both axial and circumferential velocities at the runner outlet. The velocity ratio between them has been diminished greatly at the draft tube inlet, inducing a spiral vortex rope growing with time. The cavitation will shorten the duration and reduce the maximal rotational speed of the runaway process. The runner blade pressure surface is much more critical to cavitation than the suction surface. The amplitude of pressure fluctuation in the runaway process is increasing in the main flow direction. Furthermore, the amplitude of pressure fluctuation reaches up to over 100% of the working head in the draft tube, considerably threatening the safe operation of the turbine.

Keywords

Bulb hydraulic turbine runaway process pressure fluctuation cavitation vortex rope

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References

Yamaguchi

Takoh

. An experimental research on the transient phenomena of a pumped-storage power station. J Antimicrob Chemother 1998; 41: 49–57.

Jiang

Jing

Liang

et al.

Model study and calculation of hydraulic transient in hydro power station pipeline. J Hydraul Eng 2005; 36: 1165–1170.

Liu

Sun

et al.

Three dimensional flow simulation of load rejection of a prototype pump-turbine. Eng Comput 2013; 29: 417–426.

Thanapandi

Prasad

. Centrifugal pump transient characteristics and analysis using the method of characteristics. Int J Mech Sci 1995; 37: 77–89.

Pannatier Y, Nicolet C, Kawkabani B, et al. Transient behavior of variable speed pump-turbine units. In: IAHR 24th symposium on hydraulic machinery and systems, Foz do Iguassu, Brazil, 27–31 October 2008.

Nicolet

Alligné

Kawkabani

et al.

Unstable operation of Francis pump-turbine at runaway: rigid and elastic water column oscillation modes. Int J Fluid Mach Syst 2009; 2: 324–333.

Feng

Luo

Zhu

et al.

Investigation on disk friction loss and leakage effect on performance in a Francis model turbine. Adv Mech Eng 2017; 9: 1–10.

Xiao

Wang

Yan

. Experimental and numerical analysis of blade channel vortices in a Francis turbine runner. Eng Comput 2011; 28: 154–171.

Liu

Sun

et al.

Three-dimensional flow simulation of transient power interruption process of a prototype pump-turbine at pump mode. J Mech Sci Technol 2013; 27: 1305–1312.

10.

Wu D, Liu Q, Wu P, et al. Simulations on dynamic characteristics of pump and pipe system during pumps and valves adjusting process. In: 26th IAHR symposium on hydraulic machinery and systems, Beijing, China, 19–23 August 2012.

11.

Zhang

Cheng

Yang

. Simulation of the load rejection transient process of a Francis turbine by using a 1-D-3-D coupling approach. J Hydrodyn Ser B 2014; 26: 715–724.

12.

Karney

et al.

Three dimensional transient simulation of a prototype pump-turbine during normal turbine shutdown. J Hydraul Res 2017; 55: 520–537.

13.

Avdyushenko

Cherny

Chirkov

. Numerical simulation of transient processes in hydro turbines. Thermophys Aeromech 2013; 20: 577–593.

14.

Zhou

Liu

. Three-dimensional CFD simulation of the runaway transients of a propeller turbine model. J Hydraul Eng 2010; 41: 233–238.

15.

Liu S, Zhou D, Liu D, et al. Runaway transient simulation of a model Kaplan turbine. In: IOP conference series: earth and environmental science, 2010, pp. 793–798.

16.

Song

Yan

. Transient hydrodynamic analysis of the transition process of bulb hydraulic turbine. Adv Eng Softw 2015; 90: 152–158.

17.

Wang

et al.

Analysis of transient flow in a pump-turbine during the load rejection process. J Mech Sci Technol 2018; 32: 2069–2078.

18.

Ramos

Almeida

. Dynamic orifice model on water-hammer analysis of high or medium heads of small hydropower schemes. J Hydraul Res 2001; 39: 429–436.

19.

Chirag

Cervantes

Bhupendrakumar

et al.

Pressure measurements on a high-head Francis turbine during load acceptance and rejection. J Hydraul Res 2014; 52: 283–297.

20.

Chirag

Cervantes

Gandhi

et al.

Transient pressure measurements on a high head model Francis turbine during emergency shutdown, total load rejection, and runaway. J Fluids Eng 2014; 136: 121107–121107.

21.

Amiri

Mulu

Raisee

et al.

Unsteady pressure measurements on the runner of a Kaplan turbine during load acceptance and load rejection. J Hydraul Res 2016; 54: 56–73.

22.

Roache

. Quantification of uncertainty in computational fluid dynamics. Annu Rev Fluid Mech 1997; 29: 123–160.

23.

Karimia

Akdogana

Dellimoreb

et al.

Quantification of numerical uncertainty in computational fluid dynamics modelling of hydrocyclones. Comput Chem Eng 2012; 43: 45–54.

24.

Kolšek

Duhovnik

Bergant

. Simulation of unsteady flow and runner rotation during shut-down of an axial water turbine. J Hydraul Res 2006; 44: 129–137.

25.

Menter

. Two-equation eddy viscosity turbulence models for engineering applications. AIAA J 1994; 32: 1598–1605.

26.

IEC-60193. Hydraulic turbines, storage pumps and pump-turbines model acceptance tests, 1999.

27.

Liu

. Hydraulic turbine, Beijing: China Water & Power Press, 2008.

Numerical analysis of transient characteristics of a bulb hydraulic turbine during runaway transient process

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