The Aerodynamic Analysis of Rotary Wing Blade Flapping and Wake Dynamics Coupled System

• Main Authors: Chang, Li, 張立
• Other Authors: Wang Yi-Ren
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/39615615589932730186

碩士 === 淡江大學 === 機械工程學系 === 84 === An analytic model and numerical scheme have been developed to predict the aerodynamic loads on helicopter rotors due to various blade chord length in hover and forward flight. The Peters'' finite state inflow theory is chosen for a wake modeling. The blade element theory and lifting line theory are used to formulate the aerodynamic forces for a blade. The aerodynamic system that we deal with in this thesis is a closed loop system, since we consider the feedback of wake oscillating which will affect the lift change as well as the blade chord length. Both collective and cyclic flapping with wake effects were alsoconsidered. Results show that the collective flapping case has less chord wise lift distribution than a non-flapping motion. This may be explained as follows, the flapping motion will increase the blade angle of attack, the strength of the bound circulation also increases. This, in term, increases the strength of the trailing wake and shed wake, which induces larger downwash along the span and decreases the effective angle of attack. Due to different phases will cancel each other and reduce the lift, The cyclic flapping motion has less lift distribution than collective motion. The model can also predict rotor disk lift coefficient distributions and rotor performance very well in various flight condition and different blade taper ratios.