Carefree Hybrid Methodology for Rotor Hover Performance Analysis

A new, hierarchical hybrid computational fluid dynamics–free wake method has been assessed for the S-76 rotor in hover. The computational fluid dynamics–free wake-based dual-solver approach addresses the industry needs for computational fluid dynamics accuracy at reduced costs for design and analysis. This solver is capable of modeling model multiple blades, rotors, and bodies, and it is not limited to a single rotor blade as in many dual-solver hybrid approaches. Hover predictions have been evaluated with three different blade-tip configurations, along with three different tip Mach numbers for a swept and tapered tip. The computational fluid dynamics–free wake simulations produced integrated performance coefficients comparable to or more accurate than those achieved by most full computational fluid dynamics with larger meshes or other hybrid methods. The hybrid approach provides cost savings and is within four counts of the experimental figure of merit and two counts of computational fluid dynamics alone results for the collective sweep performed. The use of this hybrid method significantly decreased computational time and cost with a reduced-size mesh costing 51.3% of a computational fluid dynamics model.