Ground Effect in Thrust-Lift Conversion using the Deflected Slipstream Concept in Martian Conditions

Abstract

Abstract. As interest in Mars exploration grows, there is an increasing demand for versatile unmanned aerial systems (UAS) capable of vertical takeoff and landing (VTOL), driving the development of lightweight, high-lift configurations. Among these, the propeller–wing configuration with a deflected slipstream (DS) system, known as a DS-blown wing, enables efficient thrust–lift conversion. However, during VTOL, the ground effect can substantially alter the flow field and affect this conversion efficiency. Three-dimensional unsteady Reynolds-Averaged Navier–Stokes (URANS) simulations with fully resolved propeller-blade geometry were conducted to evaluate the thrust-lift conversion efficiency at various ground clearances and to examine the aerodynamic interactions among the propeller-induced flow, the deflected flap, and the ground surface. The results show that the DS-blown wing exhibits reduced efficiency in ground effect compared with out-of-ground-effect conditions, primarily due to a recirculation region beneath the wing that modifies the pressure distribution. When the wing operates in very close proximity to the ground, a rebound in thrust-lift conversion efficiency is observed. Moreover, at certain intermediate heights, a resonance phenomenon occurs, leading to large-amplitude lift fluctuations at the blade-passing frequency. This work enhances the understanding of DS-blown wing aerodynamics in ground effect under Martian conditions and provides valuable guidance for the design of future Mars UAS.