Research Papers: Flows in Complex Systems

Numerical Calculation of Unsteady Flow Fields: Feasibility of Applying the Weis-Fogh Mechanism to Water Turbines

[+] Author and Article Information
Kideok Ro

Department of Mechanical System Engineering,
Institute of Marine Industry,
Gyeongsang National University,
445 Inpyeong-dong, Tongyeong, Gyeongnam 650-160, South Korea
e-mail: rokid@ gnu.ac.kr

Baoshan Zhu

Department of Thermal Engineering,
State Key Laboratory of Hydroscience and Engineering,
Tsinghua University,
Beijing 100084, China

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the Journal of Fluids Engineering. Manuscript received September 19, 2012; final manuscript received July 3, 2013; published online August 6, 2013. Assoc. Editor: Chunill Hah.

J. Fluids Eng 135(10), 101103 (Aug 06, 2013) (6 pages) Paper No: FE-12-1458; doi: 10.1115/1.4024956 History: Received September 19, 2012; Revised July 03, 2013

In this study, a reciprocating-type water turbine model that applies the principle of the Weis-Fogh mechanism was proposed, and the model's unsteady flow field was calculated by an advanced vortex method. The primary conditions were as follows: wing chord C=1, wing shaft stroke length hs=2.5C, and the maximum opening angle of the wing α=36deg. The dynamic characteristics and unsteady flow fields of a Weis-Fogh type water turbine were investigated with velocity ratios U/V = 1.0 ∼ 3.0. Force coefficients Cu and Cv acting on the wing in the U and V directions, respectively, were found to have a strong correlation each other. The size of a separated region on the back face of the wing increased as the velocity ratio increased and as the wing approached the opposite wall. The rapid drop in Cv during a stroke increased as the velocity ratio increased, and the average Cu and Cv increased as the velocity ratio increased. The maximum efficiency of this water turbine was 14.1% at U/V = 2.0 for one wing.

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Fig. 1

Model of Weis-Fogh-type water turbine

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Fig. 3

Definition of Fu and Fv on the wing

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Fig. 4

Time variations of Cu and Cv on the wing at different velocity ratios

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Fig. 5

Pressure distributions around the wing at the center of the water channel (U/V = 1.0)

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Fig. 6

Pressure distributions around the wing at the center of the water channel (U/V = 2.0)

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Fig. 7

Vortex distributions and velocity vectors around wing at different positions (A–C correspond to A–C in Fig. 4(b).)

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Fig. 8

Time variation of Cv on the wing for one stroke at different velocity ratios

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Fig. 9

Vortex distributions and streamlines around the wing at the center of the water channel (1∼3 correspond to U/V = 1.0~3.0 in Fig. 8)



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