Abstract
Blade Element Momentum (BEM) and Free Vortex Wake (FVW) methods play a pivotal role in the design and analysis of wind and marine hydrokinetic turbine technologies, including assessment of load response, power performance, cavitation potential, and near-wake flow. In this study, we aims at validating a multi-physics simulation tool, OpenFAST (capable of utilizing both BEM and FVW through the AeroDyn module), with experimental measurements obtained from a water tunnel test of a 1:8.7 scale model of the US Department of Energy’s marine hydrokinetic family 1 (MHKF1) reference marine turbine rotor. The water tunnel experiment measured a range of parameters including power production, blade loading, near-wake flow, cavitation effects, noise generation, and principal stress and strain at the mid span location. The experimental data obtained from the scaled marine hydrokinetic turbine rotor provides an excellent benchmark for the validation of the BEM and FVW models.
We focus on the validation and comparison of rotor coefficients (power, torque, and thrust) as a function of tip speed ratio (TSR) and mean velocity measurements of the inflow and near-wake measurements less than half a diameter downstream. Furthermore, estimated cavitation potential at various TSRs and principal stress and strain obtained by utilizing ElastoDyn module are compared with the measurements. The validation results provide important insights into the accuracy of BEM and FVW models. The study also highlights the potential limitations, which can inform future research directions, of these methods. Specifically, the estimated coefficients from BEM and FVW models agree well with the measured data at most of inflow speed conditions (2.0 - 5.0 m/s)[NN(E1] , but they show larger discrepancies at the highest inflow speed of 7.0 m/s Additionally, due to the limitations of the model in simulating the effect of blockage and flow around the hub and nacelle, the estimated near-wake flows exhibit disagreement with the measured data.
Sandia National Laboratories 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.