The mechanical power and wake flow field of a 1:40 scale model of the US Department of Energy’s Reference Model 1 (RM1) dual rotor tidal energy converter are characterized in an open-channel flume to evaluate power performance and wake flow recovery. The NACA-63(4)-24 hydrofoil profile in the original RM1 design is replaced with a NACA-4415 profile to minimize the Reynolds dependency of lift and drag characteristics at the test chord Reynolds number. Precise blade angular position and torque measurements were synchronized with three acoustic Doppler velocimeters (ADV) aligned with each rotor centerline and the midpoint between the rotor axes. Flow conditions for each case were controlled to maintain a hub height velocity, uhub = 1.04 ms−1, a flow Reynolds number, ReD = 4.4 × 105, and a blade chord length Reynolds number, Rec = 3.1 × 105. Performance was measured for a range of tip-speed ratios by varying rotor angular velocity. Peak power coefficients, CP = 0.48 (right rotor) and CP = 0.43 (left rotor), were observed at a tip speed ratio, λ = 5.1. Vertical velocity profiles collected in the wake of each rotor between 1 and 10 rotor diameters are used to estimate the turbulent flow recovery in the wake, as well as the interaction of the counter-rotating rotor wakes. The observed performance characteristics of the dual rotor configuration in the present study are found to be similar to those for single rotor investigations in other studies. Similarities between dual and single rotor far-wake characteristics are also observed.
Bibliographical noteFunding Information:
The Reference Model Project (RMP), sponsored by the U.S. Department of Energy (DOE), created six marine energy prototypes as reference models (RMs) to benchmark performance and costs for technology developers, and to serve as non-proprietary test articles for open R&D of marine energy generation systems . Open-source RMP products and supporting documentation are available at the Tethys Engineering Signature Project website (https://tethys-engineering.pnnl.gov/signature-pr ojects/reference-model-project) to facilitate their use in future R&D studies by industry, academia, and national laboratories . These products include: technical specifications and computer-aided design (CAD) files for each RM device to allow exact replication for physical and numerical modeling studies; resource site information used to design each RM device; and references to physical modeling data sets that can be used to validate numerical modeling design and analysis tools.
Funding: This work was funded by the Department of Energy Wind and Water Power Program through Sandia National Laboratories (SNL). SNL is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.
- Marine energy
- Rotor performance
- Wake flow