Advances in Lattice-Boltzmann Modeling of Proprotor–Wing Aerodynamics: Boundary Conditions and Proprotor Model Comparisons

Abstract:
This study evaluates the predictive accuracy and computational efficiency of a mid-fidelity Lattice-Boltzmann Method (LBM) framework in simulating the complex aerodynamic interactions of a tilting proprotor–wing configuration. The analysis focuses on the tiltrotor conversion maneuver, investigating a range of proprotor tilt angles from forward towards edgewise and vertical flight. To resolve the interactional flow physics, the LBM framework was integrated with two distinct proprotor modeling approaches, an Actuator Line Method (ALM) and an unsteady Actuator Disk Method (ADM), and two wall model boundary conditions, the explicit power-law and Reichardt’s log-law. The computational models were compared with experimental wind tunnel measurements and high-fidelity computational fluid dynamics (CFD) simulations. The ALM significantly outperformed the ADM in capturing discrete tip vortices and wake turbulence, which were critical for resolving the complex flow fields and wing surface pressure distributions. Reichardt’s log-law wall model demonstrated greater physical accuracy over the power-law model by correctly preserving proprotor wake alignment and improving surface pressure predictions. Modifications to the wall models and co-locating both the proprotor and the wing within the finest mesh refinement level enabled the LBM to accurately capture lift coefficient trends and magnitudes across the conversion maneuver. While limitations were identified in resolving leading edge flow attachment at high tilt angles and resolution-sensitive wing drag, this study demonstrated that the LBM-ALM approach with log-law wall model is a highly effective tool for rapid and accurate aerodynamic analysis of tilting proprotor-wing systems.

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