Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine

Experiments were performed with a large laboratory-scale high solidity cross-flow turbine to investigate Reynolds number effects on performance and wake characteristics and to establish scale thresholds for physical and numerical modeling of individual devices and arrays. It was demonstrated that the performance of the cross-flow turbine becomes essentially R e -independent at a Reynolds number based on the rotor diameter R e D ≈ 10 6 or an approximate average Reynolds number based on the blade chord length R e c ≈ 2 × 10 5 . A simple model that calculates the peak torque coefficient from static foil data and cross-flow turbine kinematics was shown to be a reasonable predictor for Reynolds number dependence of an actual cross-flow turbine operating under dynamic conditions. Mean velocity and turbulence measurements in the near-wake showed subtle differences over the range of R e investigated. However, when transport terms for the streamwise momentum and mean kinetic energy were calculated, a similar R e threshold was revealed. These results imply that physical model studies of cross-flow turbines should achieve R e D ∼ 10 6 to properly approximate both the performance and wake dynamics of full-scale devices and arrays

UNH-RVAT 3-D Spalart--Allmaras RANS simulation results

Results from simulating the UNH-RVAT cross-flow turbine in three dimensions with the Spalart--Allmaras RANS model in OpenFOAM 2.3.x (590d57f32fed). See link below for case files (note: use the `SpalartAllmaras` branch), which include a script for downloading and extracting, as well as scripts for post-processing

OpenFOAM cylindrical actuator surface case files

<p>Case files for simulating an actuator surface (approximately cylindrical actuationDiskSource) with OpenFOAM's simpleFoam solver. See the GitHub link below for the most recent version.</p

UNH-RVAT Reynolds number dependence experiment: Reduced dataset and processing code

<p>This repository contains the reduced dataset and processing code from the UNH-RVAT Reynolds number dependence tow tank experiment. For the most recent version, clone the Git repository linked below. </p

UNH-RVAT CAD models

<p>STEP CAD models for the UNH Reference Vertical Axis Turbine (UNH-RVAT). Includes simplified models for use in CFD simulations. </p

UNH-RVAT Vortexje simulation code

<p>Simulating the UNH-RVAT with the Vortexje vortex panel method API. See the GitHub link below for the most recent version.</p

UNH-RVAT 3-D SST RANS simulation results

Results from simulating the UNH-RVAT cross-flow turbine in three dimensions using the k-omega SST RANS model in OpenFOAM 2.3.x (590d57f32fed). See the link below for case files and download instructions