A Prescribed-Wake Vortex Lattice Method for Preliminary Design of Co-Axial, Dual-Rotor Wind Turbines

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Rosenberg, Aaron
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Sharma, Anupam
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Aerospace Engineering

The Department of Aerospace Engineering seeks to instruct the design, analysis, testing, and operation of vehicles which operate in air, water, or space, including studies of aerodynamics, structure mechanics, propulsion, and the like.

The Department of Aerospace Engineering was organized as the Department of Aeronautical Engineering in 1942. Its name was changed to the Department of Aerospace Engineering in 1961. In 1990, the department absorbed the Department of Engineering Science and Mechanics and became the Department of Aerospace Engineering and Engineering Mechanics. In 2003 the name was changed back to the Department of Aerospace Engineering.

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  • Department of Aerospace Engineering and Engineering Mechanics (1990-2003)

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This paper extends the prescribed-wake vortex lattice method (VLM) to perform aerodynamic analysis of dual-rotor wind turbines (DRWTs). A DRWT turbine consists of a large, primary rotor placed co-axially behind a smaller, secondary rotor. The additional vortex system introduced by the secondary rotor of a DRWT is modeled while taking into account the singularities that can occur when the trailing vortices from the secondary (upstream) rotor interact with the bound vortices of the main (downstream) rotor. Pseudo-steady assumption is invoked, and averaging over multiple relative rotor positions is performed to account for the primary and secondary rotors operating at different rotational velocities. The VLM solver is first validated against experiments and blade element momentum theory results for a conventional, single-rotor turbine. The solver is then verified for two DRWT designs against results from two computational fluid dynamics (CFD) methods: (1) Reynolds-averaged Navier–Stokes CFD with an actuator disk representation of the turbine rotors and (2) large-eddy simulations with an actuator line model. Radial distributions of sectional torque force and angle of attack show reasonable agreement between the three methods. Results of parametric sweeps performed using VLM agree qualitatively with the Reynolds-averaged Navier–Stokes (RANS) CFD results demonstrating that the proposed VLM can be used to guide preliminary design of DRWTs.


This is a manuscript of an article published as Rosenberg, Aaron, and Anupam Sharma. "A prescribed-wake vortex lattice method for preliminary design of co-axial, dual-rotor wind turbines." Journal of Solar Energy Engineering 138, no. 6 (2016): 061002. DOI: 10.1115/1.4034350. Posted with permission.

Fri Jan 01 00:00:00 UTC 2016