用于旋翼气动特性计算的一种时间推进自由涡新方法

建立了一个新的用于旋翼尾迹和诱导速度分析的时间推进自由涡计算方法.在该方法中,推导了一个新的二步二阶预测-校正差分算法--"D2PC"算法,并对采用该算法离散表示的涡线主控方程进行修正,以提高尾迹的求解精度;基于Vatistas公式给出涡核模型,并考虑了实际的耗散影响;采用更适合于旋翼气动特性计算的简化升力面桨叶气动模型;同时在自由涡方法中结合了挥舞动力学模型和旋翼配平模型.通过计算的旋翼尾迹几何形状和下洗速度与实验值的对比,验证了本文建立的自由涡方法的有效性.然后利用该方法,计算和分析了在悬停和前飞状态旋翼的尾迹几何形状和下洗诱导速度.

A new time-marching free vortex method applied for calculation on rotor aerodynamic characteristics

A new time-marching free vortex method for calculation on rotor wake and induced velocities is developed. In this method, a new 2-step 2-order accurate predictor-corrector with backward difference algorithm-named "D2PC" is deduced. In order to increase the accuracy of the solution for rotor wake, the discrete approximation of vortex governing equation using "D2PC" algorithm is modified and improved. Based on the Vatistas formula, the vortex core model is given which is under the consideration of vortex diffusion. The blade is simulated by the simplified lift-surfacing model, in which the determining method on blade bound vorticity strength is re-derived. In the free vortex method, the blade flap model and trimming model are also combined. By the comparisons of calculated results with experimental results for some numerical examples on wake geometries and induced velocities, the present free vortex method is validated. Then using the method, characteristics on rotor wake geometries and induced velocities for hover and forward flight are calculated and analyzed.