Next Generation Modeling Technology for High Speed Rotorcraft

Development of a new generation of high speed rotorcraft has been hampered by both an absence of strong predictive methods for rotors operating at very high advance ratio and a dearth of relevant test data. Phase I initiated work on these challenges with rotor tests and development of enhanced analyses for high speed flight. Phase I testing produced useful data on model scale autorotating rotors at advance ratios up to 1.7, thereby supporting analysis development and laying the groundwork for further Phase II testing. Enhanced yawed flow models for comprehensive rotorcraft analyses were also investigated and an enhanced lifting surface blade/wake model was developed and validated for improved modeling in this regime. Additionally, Phase I studied CFD grid generation and flow analysis methods for improved modeling of reversed and strong spanwise flows. Phase II will see further high advance ratio rotor tests, up to 2.5, and CFD analysis supporting the development of new validated models suitable for extreme yawed flow. These new models will be incorporated into CDI's commercial rotorcraft aerodynamics software for immediate use in rotorcraft design and flight simulation codes. A hierarchy of models will be developed supporting applications ranging from high resolution CFD to real-time simulation.