0
Research Papers: Flows in Complex Systems

Experimental Investigation of a High Head Francis Turbine During Spin-No-Load Operation

[+] Author and Article Information
Chirag Trivedi

Norwegian University of Science and Technology,
Trondheim 7491, Norway
e-mail: chirag.trivedi@ntnu.no

Michel J. Cervantes

Professor
Luleå University of Technology,
Luleå 971 87, Sweden
Norwegian University of Science and Technology,
Trondheim 7491, Norway
e-mail: michel.cervantes@ltu.se

Ole G. Dahlhaug

Professor
Norwegian University of Science and Technology,
Trondheim 7491, Norway
e-mail: ole.g.dahlhaug@ntnu.no

B. K. Gandhi

Mem. ASME
Professor
Indian Institute of Technology,
Roorkee 247 667, India
e-mail: bkgmefme@iitr.ernet.in

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received September 17, 2014; final manuscript received January 14, 2015; published online March 13, 2015. Assoc. Editor: Edward M. Bennett.

J. Fluids Eng 137(6), 061106 (Jun 01, 2015) (10 pages) Paper No: FE-14-1516; doi: 10.1115/1.4029729 History: Received September 17, 2014; Revised January 14, 2015; Online March 13, 2015

Water passes freely through a hydraulic turbine in the absence of power requirements or during maintenance of the transmission lines, spillways, or dam. Moreover, the turbine operates under no-load conditions prior to generator synchronization during startup and after the generator disconnection from the grid load for shutdown. High-velocity swirling flow during spin-no-load (SNL) induces unsteady pressure pulsations in the turbine, and these pulsations cause fatigue in the blades. To investigate the amplitude of unsteady pressure loading, transient pressure measurements were carried out in a model Francis turbine during SNL. A total of six pressure sensors were mounted inside the turbine, i.e., one in the vaneless space, three on the blade surfaces, and two in the draft tube, and three discharge conditions were investigated over the operating range of the turbine. Analysis of the unsteady pressure data showed that the runner blades experience high-amplitude pressure loading during SNL. The amplitudes at all sensor locations were high compared with those under the normal operating condition of the turbine, i.e., the best efficiency point (BEP), and increased as the discharge through the turbine increased.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Schematic of the model Francis turbine, data acquisition systems, and locations of the mounted pressure sensors: (a) PTX1—turbine inlet pipeline, (b) PTX2—casing inlet, (c) VL01—vaneless space, (d) P42—blade pressure side, (e) P71—blade trailing edge, (f) S51—blade suction side, and (g) DT11 and DT21 in the draft tube cone

Grahic Jump Location
Fig. 2

Constant efficiency hill diagram of the model Francis turbine (D = 0.349 m, H = 12 m); the vertical dot line at nED = 0.18 indicates the dimensionless synchronous speed of the model and prototype turbine runner, BEP (ηh = 93.4%, nED = 0.18, and QED = 0.15), and α corresponds to the angular position of the guide vanes in degree [20]

Grahic Jump Location
Fig. 3

Acquired and normalized discharge values during guide vanes opening from 0% to 100%: (a) acquired values of discharge (Q) and (b) normalized values of discharge (Qnorm) using Eq. (1)

Grahic Jump Location
Fig. 4

Postprocessing of the pressure-time signal acquired by sensor VL01 located in the vaneless space during runner acceleration with opening of the guide vanes from 0% to 100%: (a) acquired pressure-time signal of the full time length acquired during the measurements and instantaneous mean of the fluctuations; (b) extracted pressure fluctuations after subtraction of the instantaneous mean value; (c) normalized pressure fluctuations using Eq. (4); and (d) spectrogram of the frequency and amplitude variation of the pressure at VL01

Grahic Jump Location
Fig. 5

Transient variation of the discharge (Q), runner angular speed (n), and head (H) during SNL for opening (α) of the guide vanes from 0% to 70%

Grahic Jump Location
Fig. 6

Transient variation of the discharge (Q), runner angular speed (n), and head (H) during SNL for closing (α) of the guide vanes from 70% to 0%

Grahic Jump Location
Fig. 7

Transient pressure variation at the turbine inlet pipeline (PTX2) during guide vane opening from 0% to 70%; bold line on the time axis indicates the time of the guide vane opening

Grahic Jump Location
Fig. 8

Frequency and amplitude variation at location PTX2 during guide vane opening from 0% to 70%

Grahic Jump Location
Fig. 9

Transient pressure variation at the vaneless space (VL01) during guide vane opening from 0% to 70%; bold line on time axis indicates the time of the guide vane opening

Grahic Jump Location
Fig. 10

Frequency and amplitude variation at the vaneless space during runner acceleration as the guide vanes operate from 0% to 70% opening

Grahic Jump Location
Fig. 11

Transient pressure variation at the vaneless space (VL01) during guide vane closing from 70% to 0%; bold line on the time axis indicates the time of the guide vane closing

Grahic Jump Location
Fig. 12

Transient pressure variation at the blade pressure side location P42 during guide vane opening from 0% to 70%; bold line on the time axis indicates the time of the guide vane opening

Grahic Jump Location
Fig. 13

Transient pressure variation at the blade trailing edge location P71 during guide vane opening from 0% to 70%; bold line on the time axis indicates the time of the guide vane opening

Grahic Jump Location
Fig. 14

Transient pressure variation at the runner downstream (DT21) during guide vane opening from 0% to 70%; bold line on the time axis indicates the time of the guide vane opening

Grahic Jump Location
Fig. 15

Transient pressure variation at the runner downstream location DT21 during guide vane opening from 0% to 70%; bold line on the time axis indicates the time of the guide vane opening

Grahic Jump Location
Fig. 16

Transient pressure variation at the runner downstream location DT21 during guide vane closing from 70% to 0%; bold line on the time axis indicates the time of the guide vane closing

Grahic Jump Location
Fig. 17

Spectrogram of transient pressure variation at the location DT21 in the draft tube cone during guide vane closing from 70% to 0%

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