No abstract

A hierarchy of computational methods for Horizontal Axis Wind Turbine (HAWT) flow field is proposed, focusing on rotor models for Reynolds-Averaged Navier-Stokes simulations. Three models are systematically compared to determine their adequacy to capture performance and wake dynamics, and the trade-offs between accuracy and computational cost. The Rotating Reference Frame model is prescribed for detailed flow field studies, specifically at the root and blade tip. The Blade Element Model does not reproduce the near wake region but successfully predicts the velocity deficit in the axisymmetric far wake, and the power and torque coefficients. The Actuator Disk Model underestimates the velocity deficit in the far wake, but can be corrected to perform simulations of large wind farms. This methodology is applied to a canonical rotor and compared against experimental data. These models span three orders of magnitude in computational time and cost for the study of HAWT aerodynamic performance and wake interaction.

This paper presents an experimental and numerical study of a scale-model Horizontal Axis Hydrokinetic Turbine (HAHT). The model turbine is based on the U.S. Department of Energy Reference Model 1 (RM1), with the blade geometry modified to reproduce the design Cp–TSR performance curve of the RM1 at the flume scale Reynolds numbers (5 × 104–10 × 105). The performance and wake structure of a 45:1 scale turbine were measured using a load cell (torque applied on shaft) and a magnetic angular encoder (rotor rpm), and by planar particle image velocimetry, respectively. The details of the rotor flow field and three-dimensional wake evolution are analyzed from the numerical solution of the RANS equations solved around a computational model of the turbine. The comparison of experimental and numerical results highlights the strengths and limitations of the experimental and numerical analyses in the characterization of HAHT. Useful guidelines for developing experimental flume scale data and using them for validating numerical tools, as well as for performing a similar type of analysis and design validation of full scale devices as pilot projects start to go in the water in the United States, are provided.

The interaction of sediment with Marine Hydrokinetic (MHK) Turbines is studied via turbulent flow simulation coupled with a model for particle dynamics. The Discrete Random Walk (DRW) model is commonly used for simulations of particle dispersion in environmental flows. A method to improve the accuracy of the DRW model in conjunction with RANS simulations of the flow around MHK turbines is presented. A key issues for the use of the DRW model in marine applications is identified, finding the right characteristic eddy lifetime scale, and a simple methodology based on G.I. Taylor's classical dispersion theory is develop to calibrate this physical model parameter. The model is validated against experiments in the literature and the physics of suspended sediment transport in the wake of an MHK turbine is studied with this improved method. The qualitative changes observed in the particle trajectories agree well with theoretical and empirical observations and the quantitive trends allow for comparison of multiple particle cases under di↵erent flow conditions, confirming that this implementation of CFD

No abstract