Research Papers

Ducted Wind Turbine Optimization

[+] Author and Article Information
Ravon Venters

Mechanical and Aeronautical
Engineering Department,
Clarkson University,
Potsdam, NY 13699-5725
e-mail: venterrm@clarkson.edu

Brian T. Helenbrook

Mechanical and Aeronautical
Engineering Department,
Clarkson University,
Potsdam, NY 13699-5725
e-mail: helenbrk@clarkson.edu

Kenneth D. Visser

Associate Professor
Mechanical and Aeronautical
Engineering Department,
Clarkson University,
Potsdam, NY 13699-5725
e-mail: visser@clarkson.edu

1Corresponding author.

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received March 10, 2016; final manuscript received August 1, 2017; published online November 29, 2017. Assoc. Editor: Douglas Cairns.

J. Sol. Energy Eng 140(1), 011005 (Nov 29, 2017) (8 pages) Paper No: SOL-16-1123; doi: 10.1115/1.4037741 History: Received March 10, 2016; Revised August 01, 2017

This study presents a numerical optimization of a ducted wind turbine (DWT) to maximize power output. The cross section of the duct was an Eppler 423 airfoil, which is a cambered airfoil with a high lift coefficient (CL). The rotor was modeled as an actuator disk, and the Reynolds-averaged Navier–Stokes (RANS) k–ε model was used to simulate the flow. The optimization determined the optimal placement and angle for the duct relative to the rotor disk, as well as the optimal coefficient of thrust for the rotor. It was determined that the optimal coefficient of thrust is similar to an open rotor in spite of the fact that the local flow velocity is modified by the duct. The optimal angle of attack of the duct was much larger than the separation angle of attack of the airfoil in a freestream. Large angles of attack did not induce separation on the duct because the expansion caused by the rotor disk helped keep the flow attached. For the same rotor area, the power output of the largest DWT was 66% greater than an open rotor. For the same total cross-sectional area of the entire device, the DWT also outperformed an open rotor, exceeding Betz's limit by a small margin.

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Grahic Jump Location
Fig. 1

Conceptual design of a DWT. The geometry of the duct's cross section is that of a highly cambered airfoil.

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Fig. 2

Eppler 423 airfoil geometry

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Fig. 3

Domain and mesh used for the airfoil validation study: (a) domain and mesh and (b) boundary layer mesh

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Fig. 4

Convergence of k–ε model

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Fig. 5

E423 at Re = 3.0 × 105 and 1.0 × 106 compared to experimental data

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Fig. 6

E423 at Re = 1.0 × 106: coefficient of pressure and shear stress versus chord length

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Fig. 7

Detail of parameters for duct optimization

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Fig. 8

Domain and mesh for the optimization studies: (a) domain and mesh and (b) magnified region around actuator disk

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Fig. 9

Convergence plot: Cp versus mesh resolution (number of elements)

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Fig. 10

Response surface: CT versus AOA for DWT for chord length of 45% at the optimal CP

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Fig. 11

Velocity contours overlaid by streamlines for the optimal duct configuration

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Fig. 12

Coefficient of pressure and friction for the optimal duct design with c/D = 22.5%

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Fig. 13

Response surface: Δr/D versus Δz/D or chord length of 45% at the optimal CP

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Fig. 14

Response surface: CT versus AOA for DWT for chord length of 45% at the optimal CP,total

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Fig. 15

Response surface: Δr/D versus Δz/D or chord length of 45% at the optimal CP,total




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