Evaluation Of The Velocity Potential-Based Finite-State Model For Ground Effect Using A State-Space Free Vortex Wake Model

Abstract

A velocity potential-based finite state model (VPBFSM) has been developed to analyze an isolated rotor in ground effect. The model uses mass source distributions to represent the ground and imposes the non-penetration of flow boundary condition. In this study, evaluations are performed by comparing the VPBFSM inflow distribution to that predicted by a high-fidelity free wake model for both full and inclined ground effect cases. The analysis is conducted for the UH-60 rotor using geometric and aerodynamic data from the literature. The VPBFSM exhibits good agreement with the free wake model in both ground effect cases, capturing the expected trend of decreasing inflow as the rotor approaches the ground, particularly on the side closest to the surface. Some discrepancies in magnitude are observed between the models however, these remain acceptable, as they stem from the VPBFSM's reduced-order assumptions compared to the free wake model's higher geometric and wake fidelity.