Trim Range and Characteristics of Autorotation(II): Advance Ratio Variation and Flapping Characteristics

Abstract

The flapping characteristics and advance ratios at torque equilibrium state of autorotation were investigated when the airspeed, shaft angle, and pitch angle were varied. To simulate the airspeed increase, the aerodynamic data analyzed by using the compressible Navier-Stokes solver and Pitt/Peters inflow theory were used. Transient Simulation Method(TSM) was used to catch the torque equilibrium states. The maximum flapping angles at torque equilibrium state were correlated to the airspeed, shaft angle, and pitch angle. By comparing flapping behavior to the variation of advance ratio, the phenomenon that the extension of reverse flow area of retreating blade affects the characteristics of autorotation was qualitatively considered.

The adverse cyclic and collective pitch effect in a rotor

“…The simulation results showed that the collective pitch range shrinks with a reducing rotor shaft angle. Then, in consecutive research (17) , the TSM was used to analyse a full-scale rotor. In that study, to explore the pitch setting range when a rotor experiences an increasing forward airspeed, a compressible Navier-Stokes solver was used to support the airfoil look-up table.…”