科研之友
微信
新浪微博
Facebook
分享链接
摘要
When helicopters work at fixed rotor speeds, optimal rotor efficiency cannot be achieved in all flight states. It can only be realized at different flight states by varying rotor speeds. In order to investigate the aerodynamics of variable speed rotors, an analytical model applying to low speed rotors is first derived. The Leishman-Beddoes unsteady and dynamic stall model and a modified Sheng dynamic stall model for low Mach numbers (Ma<0.3) are introduced. Then, a test in a 2.5 m diameter helicopter rotor model test rig at a low speed wind tunnel is conducted, and the effects of rotor speeds on the figure of merit and the rotor power required are investigated. Finally, the comparisons between the experimental data and calculation demonstrate that the aerodynamic characteristics for low speed rotors can be accurately predicted by the analytical model. By optimizing the rotor speed, the lift to drag ratio of an airfoil can be effectively improved by the increase of the angle of attack. When the rotor is working at the optimal rotor speed, the figure of merit can be improved by 32% and the rotor power can be maximally reduced by 22%.
- 出版日期2013
- 单位南京航空航天大学
