悬停状态旋翼固定尾迹分析中三角级数的应用

为了在固定尾迹分析中更好地描述桨叶附着涡环量分布,结合叶素理论,采用一个三角级数表达附着涡环量的连续分布,并应用于悬停状态下单旋翼和共轴双旋翼的气动特性分析,通过小量计算即获得连续光滑的附着涡环量分布,将其应用到推导的公式中计算出连续分布的诱导速度,进而分析了共轴双旋翼上下旋翼气动干扰及扭矩平衡条件.计算结果与实验结果进行了比较分析,验证了该方法的有效性,并得出结论:下旋翼总距变化对上旋翼诱导作用影响微小,但对自身诱导作用明显;当上下旋翼扭矩平衡时,下旋翼总距比上旋翼总距约大1°.

Application of trigonometric series for rigid wakes analysis of rotor aerodynamics in hover

To describe the attachment vortex circulation distribution of blades, contacting blade element theory, trigonometric series was adopted and applied for the model of classical rotor vortex theory. Some studies have been done for the air-operated characteristic of single rotor and co-axial rotors in hover. The attachment vortex circulation distribution of blades which is continuous and smooth was obtained by rough computation. While it is applied to the formulas found in the page, the induced velocity of continuous distribution can be resolved. Then analysis was done for the complex interaction between the upper and lower rotor, and the condition of balance between the torque of upper and lower rotor was got. The comparison between calculation results and experiment records shows that the previous theory and method is applicable. There are two conclusions: One is that while collective pitch of lower-rotor is changed, sharp influence is brought to lower-rotor, but it is nearly no influence for upper-rotor, the other is that when torque of upper-rotor equals to lower-rotor', the collective pitch of lower rotor is greater 1° than upper-rotor'.