Geometry design model of a tip-jet, reaction-drive rotor based on coupling analysis

Abstract

Tip-jet, reaction-drive rotor is characterized by light weight and simple structure, as it eliminates the transmission and anti-torque system which are necessary in a conventional shaft-drive helicopter. A tip-jet rotor parameters design methodology is presented by modeling the duct interior flow and rotor external aerodynamics. The inner flow model includes the influence of area, temperature, friction and rotor rotation, the rotor tension and torque is analyzed by a modified blade element method. The represented method is a rapid approach to decide jet rotor parameters in concept design stage, results of which show that section thickness and rotary speed are the main factors to tension and power balance.