典型飞行状态下的旋翼振动载荷计算与分析

Prediction and Analysis of Rotor Vibration Loads in Typical Flight Conditions

建立了基于柔性多体动力学思想的综合气弹分析方法,以SA 349/2"小羚羊"直升机为算例,对其典型飞行状态,包括一个小前进比状态,一个大前进比状态以及一个高速稳态转弯状态进行载荷计算。对于两个稳态前飞状态,采用自由尾迹模型计算诱导入流,通过配平迭代获得旋翼载荷;对于稳态转弯状态,将实测配平量作为输入量,采用G lauert线性入流模型计算诱导速度。在与试飞数据以及CAM RAD II计算结果的对比中,稳态前飞状态的计算结果与实测数据吻合较好,与CAM RAD II精度相当;对于接近飞行极限的高速转弯状态,本文计算值捕捉到了动态失速条件下旋翼载荷变化的主要特征。

This paper presents predictions of both the rotor airloads and structural loads using a comprehensive analysis based on flexible multibody dynamics method.Three typical flight conditions of SA349/2 helicopter are investigated： transition speed,high speed and steady turn.For two steady forward flight conditions,free wake model and trim procedure are used.Glauert linear inflow and trim data from flight tests are used at steady turn.Calculation results are compared with measured data from flight tests and calculations obtained using CAMRAD II.Generally,there are good agreements in forward flight conditions.For steady turn,the calculation result captures the main characteristics of rotor loads caused by dynamic stall.