Aerodynamic Interactions Between the Propeller and Other Components in a Coaxial Compound Helicopter

The coaxial compound helicopter represents a promising configuration for enhancing maximum flight speed. This configuration features a pair of coaxial rigid rotors and a rear-located propeller. Although this arrangement improves achievable forward velocity, it also introduces significant aerodynamic interference among the individual components. In the present study, aerodynamic interferences between the propeller and the remaining parts of a coaxial helicopter are investigated using a numerical approach. The rotating rotors and the propeller are modeled by employing a sliding mesh technique, while the flow field is resolved by solving the Reynolds-averaged Navier‒Stokes equations. The findings indicate that the aerodynamic impacts of the main rotor and the airframe on the propeller are strongly coupled. The wake of the main rotor leads to a reduction in the propeller thrust and thrust fluctuations at specific advance ratios, while the presence of the airframe increases the propeller thrust. Additionally, the variation in horizontal tail lift induced by the propeller exhibits opposite trends at low and high flight speeds