Sensitivity Study of High-Fidelity Hover Predictions on the Sikorsky S-76 Rotor

Abstract

Hover performance calculations are performed for a 9.34 ft, four-blade, Mach-scaled, S-76 rotor with an anhedral tip using different computational-fluid-dynamics approaches to assess the variability in predictions. Time-accurate Navier–Stokes calculations are performed using the High Performance Computing Modernization Program Computational Research and Engineering Acquisition Tools and Environments Air Vehicles Helios software suite with OVERFLOW and FUN3D as near-body solvers, and the standalone OVERFLOW solver. Different modeling options exercised include structured and unstructured meshes for the blades, adaptive mesh refinement in the blade mesh, adaptive mesh refinement in the wake mesh, and inviscid and detached-eddy simulation modeling in the wake. Rotor performance, blade airloads, and wake geometry from the different calculations show consistent predictions. The agreement between computed figure of merit and test data is good at high-thrust conditions but only fair at lower thrust.