Structured, Overset Simulations for the 1st Rotor Hub Flow Workshop

Structured, overset computational fluid dynamics methods are used to simulate a water-tunnel experiment of flow over a rotating, 4-bladed rotor hub at Reynolds numbers near that of full scale. A hybrid RANS/LES method is employed with fifth-order discretization of convective flux terms and second-order time integration to resolve largescale turbulent flow features in the wake. Preliminary simulations on a baseline grid system revealed inadequate grid resolution in the wake region along with contamination from inflow and outflow boundaries being too close to the region of interest. An improved grid system was made based on the lessons learned, and results obtained for this grid are described in detail. Comparison of time-averaged velocities in the wake show an underprediction of the velocity deficit in the mid and far wakes. Frequency spectra of the hub drag loads and downstream wake velocities are presented and compared with experiment.