Journal of Computational Fluids Engineering ISSN:1598-6071(Print) 3022-6252(Online) 한국전산유체공학회지

In this study, the aerodynamic characteristics of the 2-blade and 4-blade lift props applied to the OPPAV eVTOL were comparatively analyzed using Computational Fluid Dynamics (CFD) techniques for hover, forward flight, and stationary prop conditions during high-speed forward flight. In terms of hover performance, the Figure of Merit, calculated from power required versus thrust, was generally similar for both props. The unsteady aerodynamic analysis under forward flight conditions clearly confirmed the aerodynamic vibration reduction effect, which was the primary reason for changing the lift prop from 2 blades to 4 blades. The 4-blade lift prop showed a significant reduction in the peak-to-peak amplitude of the vibratory aerodynamic force in the thrust direction compared to the 2-blade prop under all flight conditions. Furthermore, aerodynamic vibrations in the y and z directions of the pod were also identified, caused by the prop's wake and the prop-pod aerodynamic interaction. Frequency analysis also confirmed that the increase in blade count changed the dominant vibratory frequency characteristic from 2/rev to 4/rev. An analysis of the prop drag when the prop was stationary during high-speed forward flight showed that the 2-blade lift prop exhibited minimum drag at a 0-degree blade azimuth angle, whereas the 4-blade lift prop exhibited minimum drag at 45 degrees. These findings suggest that while the 4-blade lift prop is advantageous from a rotational vibration perspective, the 2-blade lift prop may be more favorable for enhancing aircraft performance through stationary drag reduction.