Aerodynamic interactions of staggered counter-rotating rotor system

With the widespread application of Staggered Counter-rotating Rotor (SCR) systems in eVTOL and UAV configurations, a comprehensive understanding of SCR performance under Out-of-Ground Effect (OGE) and In-Ground Effect (IGE) conditions is crucial for aircraft design and landing safety. This study experimentally measured the changes in thrust and torque of the upper and lower rotors in an SCR system under varying axial and radial distances. It focuses on the interaction mechanisms between the upper and lower rotors and conducts specific IGE state experiments for certain SCR configurations. The findings reveal that changes in the lower rotor predominantly influence the overall performance of the SCR system, regardless of OGE or IGE conditions. Under OGE conditions, radial distance has a more significant impact than axial distance. Conversely, under IGE conditions, the axial distance plays a critical role in improving SCR system performance. These results provide a broad parameter range to assess SCR system performance variations, offering guidance for the design of new concept rotorcraft configurations and the development of aerodynamic prediction models under IGE conditions.