旋翼桨尖涡模型及其在自由尾迹分析中的影响

 建立了一个旋翼桨尖涡初始涡核半径计算模型，用于消除旋翼自由尾迹分析中桨尖涡涡核半径依靠经验设定的现状。该方法利用涡量和涡矩守恒关系，考虑旋转效应的影响，并修正Vatistas涡量分布函数，得到了一个关于桨尖涡初始涡核半径与桨叶附着环量分布之间的非线性关系。将新建立的初始涡核模型同先前建立的涡核扩散与拉伸模型以微分方程初值问题的形式组成一个完整的桨尖涡模型，并将其应用于自由尾迹分析方法中，分别对两副模型旋翼的悬停尾迹进行分析。计算得到的桨尖涡初始涡核半径和展向位置与实验测量值的对比表明本文模型具有较高的准确性。此外，讨论了涡核湍流动量扩散效应在自由尾迹分析中的影响，分析表明该效应对自由尾迹分析的收敛性有重要影响。

Rotor Tip Vortex Model and Its Effect on Free-vortex Wake Analysis

A model is developed for the calculation of the initial rotor tip vortex core radius aiming at eliminating the empirical parameters of the tip vortex in rotor free-vortex wake analysis. This method makes use of the conservation of wake vorticity, the moments of vorticity with the rotation effect and modified Vatistas's vorticity distribution function, and establishes a nonlinear relationship between the initial core radius and the spanwise bound circulation distribution. The new initial tip vortex model and the vortex core diffusion and stretching model together form a complete tip vortex model. The complete model is used in the free-vortex wake analysis for two model rotors in hover. The computed initial core radius and span station of the tip vortex are shown to compare favorably with experimental measurements. What is more, the effect of turbulent momentum diffusion on free-vortex wake analysis is discussed, and it is found that this effect has important influence on the convergence of rotor free wake analysis.