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共轴式直升机涡环形成的机理与单旋翼直升机相同,但涡环强度、涡环边界、有关现象特别是改出动作等方面却存在差异。根据国内外有关共轴式直升机上、下旋翼气动干扰的风洞试验和理论研究结果,分析了共轴式直升机涡环强度的特点;根据某型共轴式直升机涡环边界的试飞数据,确定并分析了其涡环上边界基本参数Vcr(90°);并根据共轴式旋翼经典理论中的模型A,计算了该机悬停状态等值旋翼的平均诱导速度υhpj及Vcr(90°);分析了共轴式直升机进入涡环后旋翼转速增加的原因;最后分析了共轴式直升机改出涡环动作中的“减小总距”问题。
The formation mechanism of a coaxial helicopter vortex ring is the same as that of a single-rotor helicopter, but there are differences in the aspects of the vortex ring strength, the boundary of the vortex ring, and related phenomena, especially the re-movement. According to the results of wind tunnel test and theoretical research at home and abroad on the aerodynamic interference of the upper and lower helicopters of coaxial helicopter, the characteristics of the vortex ring strength of the coaxial helicopter are analyzed. According to the test flight data of the vortex ring boundary of a type of coaxial helicopter, And the basic parameters Vcr (90 °) of the upper boundary of the vortex ring are analyzed. According to the model A in the classical theory of the coaxial rotor, the average induced velocities νhpj and Vcr (90 °) of the rotor in the hovering state are calculated. The reason why the rotor speed increases when the coaxial helicopter enters the vortex ring is analyzed. Finally, the problem of “reducing the total distance ” in the replacement of the vortex ring of the coaxial helicopter is analyzed.