具有后掠桨尖的旋翼气动特性计算方法

基于直同定常飞行状态旋翼尾迹的周期特性，给出了计算旋翼自由尾迹的方法和公式。将该方法和桨叶二阶升力线模型结合，建立了一个新的适用于后掠、尖削及其组合形状的旋翼气动特性计算的分析模型。该模型，对后掠桨尖的ＵＨ－６０Ａ旋翼在悬停时的桨叶载荷分布进行了计算，恙相应的试验结果作了对比。对于尖削奖尖，以ＵＨ－１旋翼为算例同定常将其矩形桨尖改变为尖削形状，通过矩形和尖削计算结果的对比，分析了尖削对旋翼气动特性

An Analytical Method for Predicting Aerodynamic Characteristics of the Rotor with a Swept Tip

A free wake model by enforcing a periodic boundary condition on the rotor wake is presented in the paper. Based on the wake model and the second-order lifting line theory, a new analytical method is emphatically developed to predict the aerodynamic behavior of the advanced rotor with a swept, tapered or swept-tapered tip shape. As examples, a comparison in hover with the experimental data on the UH-60A rotor with a swept tip is given, and the calculation on the blade section loading of a tapered-tip blade is made and compared with the result of a rectangular reference blade. In addition, the sample calculation on the tip vortex path in low-speed forward flight is also performed to validate further the method. Key words blade tip shape; aerodynamic characteristics; helicopters; rotors;free wakehe double arm link clamping system has been made based on a middle sized plastic injection machine, it is pointed out that for middle sized machines, the feasible regions bounded by constraints are nonconvex sets and the objective function with the highest efficiency coefficient is nonconvex function as well, which has more solutions, the satisfied solution in the paper is far better than the realistic design. This study provides the reasons for the choice of configurations and reasonable decision of tolerance in the design of plastic injection machines.