The effects of the installation location of propulsive rotor on the aerodynamic characteristics for ABC helicopters

Abstract

Based on the free-wake method, a comprehensive model for the analysis of the aerodynamic characteristics of ABC rotor propeller-augmented compound helicopters is established and anew trim method for the multi-control solutions of ABC helicopters is presented. The developed model is utilized to investigate the aerodynamic interference characteristics of the main rotors on the propulsive rotor and the effects of the installation location of propulsive rotor on its aerodynamic characteristics. Numerical examples show that in certain range of forward flying speed, the aerodynamic interference characteristics of the blades of main rotors on the front propulsive rotor will improve the aerodynamic performance, decrease the power consumption and decrease the vibration level of thrust of the front propulsive rotor. This advantage will be weakened, if the vertical spacing between the propeller hub of the propulsive rotor and the lower main rotor disc is increased too much. On the other hand, however, the direct aerodynamic impacts of the wake of main rotors on the regular rear propulsive rotor will degrade the aerodynamic performance, increase the power