0
Research Papers: Flows in Complex Systems

Looping Dynamic Characteristics of a Pump-Turbine in the S-shaped Region During Runaway

[+] Author and Article Information
Xiaoxi Zhang

State Key Laboratory of Water Resources and
Hydropower Engineering Science,
Wuhan University,
Wuhan 430072, China
e-mail: zhangxiaoxi@whu.edu.cn

Yongguang Cheng

State Key Laboratory of Water Resources and
Hydropower Engineering Science,
Wuhan University,
Wuhan 430072, China
e-mail: ygcheng@whu.edu.cn

Linsheng Xia

State Key Laboratory of Water Resources and
Hydropower Engineering Science,
Wuhan University,
Wuhan 430072, China
e-mail: xialinsheng@whu.edu.cn

Jiandong Yang

State Key Laboratory of Water Resources and
Hydropower Engineering Science,
Wuhan University,
Wuhan 430072, China
e-mail: jdyang@whu.edu.cn

Zhongdong Qian

State Key Laboratory of Water Resources and
Hydropower Engineering Science,
Wuhan University,
Wuhan 430072, China
e-mail: zdqian@whu.edu.cn

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received June 16, 2015; final manuscript received March 18, 2016; published online May 26, 2016. Assoc. Editor: Bart van Esch.

J. Fluids Eng 138(9), 091102 (May 26, 2016) (10 pages) Paper No: FE-15-1406; doi: 10.1115/1.4033297 History: Received June 16, 2015; Revised March 18, 2016

During transients, hydroturbines may demonstrate some dynamic characteristics that differ from the corresponding static characteristics in steady operating conditions. To study the dynamic characteristics of a pump-turbine, we simulated the runaway transients in a model pumped-storage plant by coupling one-dimensional (1D) water conveyance system and three-dimensional (3D) pump-turbine. The results show that the runaway dynamic trajectories form loops in the S-shaped region in the unit discharge and unit torque charts of the pump-turbine, not following the corresponding static characteristics. Theoretical analysis and flow patterns comparisons illustrate that the looping trajectories are mainly caused by the successive features of transient flow patterns, namely, the transient flows in the pump-turbine are influenced by their previous status. These features induce different performances between similar dynamic operating points in different moving directions. Furthermore, through comparing the transient parameters calculated by the dynamic and static characteristics separately, we found that both methods are available to capture the unstable behaviors of the pump-turbine, but the dynamic method displays more accurate results when simulating the critical transient parameters. Therefore, in practical engineering applications, we suggest to use the static characteristics method for stability analysis while dynamic characteristics method for transient parameters, which is important for optimizing the layout of water conveyance systems.

Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Chaudhry, M. H. , 2014, Applied Hydraulic Transients, 3rd ed., Springer, New York.
Yamabe, M. , 1971, “ Hysteresis Characteristics of Francis Pump-Turbine When Operated as Turbine,” ASME J. Fluids Eng., 93(1), pp. 80–84.
Olimstad, G. , Nielsen, T. , and Borresen, B. , 2012, “ Stability Limits of Reversible-Pump Turbines in Turbine Mode of Operation and Measurements of Unstable Characteristics,” ASME J. Fluids Eng., 134(11), p. 111202. [CrossRef]
Liu, J. , Liu, S. , Sun, Y. , Jiao, L. , Wu, Y. , and Wang, L. , 2013, “ Three-Dimensional Flow Simulation of Transient Power Interruption Process of a Prototype Pump-Turbine at Pump Mode,” J. Mech. Sci. Technol., 27(5), pp. 1305–1312. [CrossRef]
Nielsen, T. , 1990, “ Transient Characteristics of High Head Francis Turbines,” Ph.D. thesis, Norwegian University of Science and Technology, Trondheim, Norwegian.
Yin, J. L. , 2012, “ Study on the Internal Flow and Optimum Design of Pump Turbine in the ‘S' Zone,” Ph.D. thesis, Zejiang University, Hangzhou, China (in Chinese).
Liu, J. T. , Liu, S. H. , Sun, Y. K. , Zuo, Z. G. , and Wu, Y. L. , 2012, “ Instability Study of a Pump-Turbine at No Load Opening Based on v2-f Turbulence Model,” 26th IAHR Symposium on Hydraulic Machinery and Systems, Beijing.
Dörfler, P. , Sick, M. , and Coutu, A. , 2013, Flow-Induced Pulsation and Vibration in Hydroelectric Machinery, Springer, London.
Zhang, X. , Cheng, Y. , Xia, L. , and Yang, J. , 2014, “ Dynamic Characteristics of a Pump-Turbine During Hydraulic Transients of a Model Pumped-Storage System: 3D CFD Simulation,” IOP Conf. Ser. Earth Environ. Sci., 22, p. 032030.
Martin, C. S. , 1986, “ Stability of Pump-Turbines During Transient Operation,” 5th International Conference on Pressure Surges, Hannover, Germany.
Martin, C. S. , 1997, “ Effect of Pump-Turbines Characteristics Near Runaway on Instability,” JSME Centennial International Conference on Fluid Engineering, Tokyo.
Martin, C. S. , 2000, “ Instability of Pump-Turbines With S-Shaped Characteristics,” 20th IAHR Symposium on Hydraulic Machinery and Systems, Charlotte, NC.
Yang, Z. , Zhou, L. , and Wang, Z. , 2012, “ Turbine Efficiency Test on a Large Hydraulic Turbine Unit,” Sci. China: Technol. Sci., 55(8), pp. 2199–2205. [CrossRef]
Ruprecht, A. , and Helmrich, T. , 2003, “ Simulation of the Water Hammer in a Hydro Power Plant Caused by Draft Tube Surge,” ASME Paper No. FEDSM2003-45249.
Huang, W. D. , Fan, H. G. , and Chen, N. X. , 2012, “ Transient Simulation of Hydropower Station With Consideration of Three-Dimensional Unsteady Flow in Turbine,” IOP Conf. Ser. Earth Environ. Sci., 15, p. 052003.
Zhang, X. , and Cheng, Y. , 2012, “ Simulation of Hydraulic Transients in Hydropower Systems Using the 1-D-3-D Coupling Approach,” J. Hydrodyn., 24(4), pp. 595–604. [CrossRef]
Mssinger, P. , Conrad, P. , and Jung, A. , 2014, “ Transient Two-Phase CFD Simulation of Overload Pressure Pulsation in a Prototype Sized Francis Turbine Considering the Waterway Dynamics,” IOP Conf. Ser. Earth Environ. Sci., 22, p. 032033.
Zhang, X. , Cheng, Y. , Yang, J. , Xia, L. , and Lai, X. , 2014, “ Simulation of the Load Rejection Transient Process of a Francis Turbine by Using a 1-D-3-D Coupling Approach,” J. Hydrodyn., 26(5), pp. 715–724. [CrossRef]
Wylie, E. , Streeter, V. , and Suo, L. , 1993, Fluid Transients in Systems, Prentice Hall, Englewood Cliffs, NJ.
Durbin, P. A. , 1995, “ Separated Flow Computations With the k-Epsilon-v-Squared Model,” AIAA J., 33(4), pp. 659–664. [CrossRef]
ANSYS, 2009, “ ANSYS FLUENT 12.0 Theory Guide,” ANSYS, Inc., Canonsburg, PA.

Figures

Grahic Jump Location
Fig. 1

Schematic of the model pumped-storage system

Grahic Jump Location
Fig. 2

Measured head difference between 2# and 3# pressure sensors

Grahic Jump Location
Fig. 3

Computational domain of the model pumped-storage system

Grahic Jump Location
Fig. 5

Calculated heads with different cells

Grahic Jump Location
Fig. 6

Mesh in the distributor and impeller channels

Grahic Jump Location
Fig. 7

Comparisons between the simulated static characteristics and the measured results

Grahic Jump Location
Fig. 8

Comparisons between the simulated transient parameters and the measured results

Grahic Jump Location
Fig. 9

Comparison between the simulated and measured dynamic trajectories

Grahic Jump Location
Fig. 10

Comparisons between the dynamic trajectories and the static operating points

Grahic Jump Location
Fig. 11

Comparisons between the modified dynamic trajectories and the static operating points

Grahic Jump Location
Fig. 12

Velocity triangle at the inlet of the impeller in turbine mode of a pump-turbine

Grahic Jump Location
Fig. 13

Definition of the similar operating points

Grahic Jump Location
Fig. 14

Velocity streamlines in the middle horizontal section in vanes zone at characteristic operating points (a) DP1, (b) DP2, (c) DP3, (d) DP4, (e) DP5, (f) DP6, and (g) DP7

Grahic Jump Location
Fig. 15

Velocity streamlines in impeller channels at characteristic operating points (The normalized velocity is defined as the ratio of the local velocity magnitude over the mean velocity magnitude at the impeller inlet.) (a) DP1, (b) DP2, (c) DP3, (d) DP4, (e) DP5, (f) DP6, and (g) DP7

Grahic Jump Location
Fig. 16

Comparisons among the results of dynamic, static numerical methods and model test (a) rotational speed, (b) discharge, (c) pressure head at spiral casing inlet, and (d) pressure head at draft tube inlet

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In