前飞状态直升机旋翼的自由尾迹计算

Free Wake Calculation for Helicopter Rotor in Forward Flight

应用时间步进方法，建立了一个前飞旋翼的全展自由尾迹模型。该模型采用圆弧涡元作为基本涡元，并依据自由尾迹涡线确定远尾迹形状以使远尾迹更接近实际和自由。为表明方法的有效性，分别以ＵＨ－１和Ｈ－３４两种直升机旋翼为算例，计算了不同前飞状态的自由尾迹形状，展示出小速度时尾迹畸变和叶尖涡卷绕的重要特征。在此基础上，应用自由尾迹分析，对前飞桨叶气动载荷进行了计算，分析了计及尾迹畸变对改进载荷计算的作用。

A full span free wake model using the time stepping approach is established for predicting the distorted wake geometry of a helicopter rotor in forward flight. The model uses the curved vortex elements on the circular arc as the basic discrete elements for trailed filaments and utilizes the free wake extension to form an adaptive far wake downstream. As examples, the calculations on free wake of UH 1 and H 34 rotors are performed for different advance ratios, and the feature of highly distorted free wake shapes and the strong tendency toward a rapid wake roll up for low speed case are exhibited. Then, by applying the free wake analysis, the calculation on blade airloads is made and the discussion on the effect of wake distortion on blade airloads is given.