Analysis of rotor aerodynamic interaction characteristics based on a three-rotor system model

The dual-layer staggered multirotor aircraft represents a promising solution for operations in confined spaces. To address the aerodynamic interaction phenomena between rotors on different layers, this study conducts performance experiments and numerical simulations based on a Three-Rotor System Model (TRSM). By analyzing hovering rotor performance and wake structures under various configuration parameters, the aerodynamic characteristics of a single rotor simultaneously influenced by two adjacent rotors on the opposite layer are specifically investigated. The results show that radial spacing (L/R) is the dominant parameter governing the intensity of aerodynamic interaction between rotors, while rotational speed, axial spacing(H/R), rotation direction, and arm angle all exhibit weak correlations. Rotor performance exhibits unsteady periodic fluctuations, with thrust loss at the trough attributed to the deterioration of inflow conditions and reduction in blade pressure differential. The thrust loss and fluctuation amplitude of the lower rotor are significantly greater than those of the upper rotor. Furthermore, due to the combined slipstream and induced effects of the two adjacent rotors, the thrust loss of the TRSM is approximately three times that of the staggered counter-rotating rotor system. Partial rotor disk overlap leads to high distortion of the wake structure and the emergence of numerous irregular secondary vortices. Evaluations based on a non-dimensional configuration factor reveal that quadrotor, hexacopter, and octocopter systems achieve a favorable balance between overall vehicle size and aerodynamic efficiency at L/R = 1.6, 1.4, and 1.8R, respectively. This study provides a reference for the aerodynamic layout design and performance prediction of compact multirotor aircraft.