Investigation of Modeling Approaches to High-Fidelity Computational Predictions of Tiltrotor / Obstacle Aerodynamic Interactions

A new framework for performing high-fidelity computational aeromechanics simulations of the V-22 tiltrotor aircraft in vertical take-off and landing mode has been developed. It is built on the HPCMP CREATE-AV Helios tool and utilizes scripted input generation and automatic replacement of modular model components. This new framework has been used to investigate the impact of various approaches to modeling the rotor and obstacle aerodynamics on predictions of aircraft performance in hover near a large ground obstacle. This work builds upon the results of a previous study of modeling fidelity requirements for predicting hover performance in ground effect. The findings indicate that a medium-fidelity simulation utilizing actuator line blades and an immersed boundary obstacle can provide rotor performance predictions and flow field features with comparable accuracy to a fully-meshed approach. Analysis of the physical phenomena in these recirculating flows and a brief analysis into the mechanisms for rotor performance loss are also provided. The computational framework accurately captures trends in rotor loads and airframe download from flight test data within approximately 5%. The medium-fidelity approach required 83% fewer computational resources, representing a 6X speedup.