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1、南京航空航天大学硕士学位论文旋翼振动载荷计算与分析姓名：孙韬申请学位级别：硕士专业：飞行器设计指导教师：王浩文2010-12南京航空航天大学硕士学位论文 I 摘 要 复杂的非定常气流环境与各种耦合效应使旋翼载荷预估成为直升机设计领域的难题。载荷计算是旋翼设计的核心课题，一方面，无论是在概念设计阶段还是在详细设计阶段，快速准确的载荷预估能力，可以有效的缩短型号研制周期，节约试验成本，规避项目风险；另一方面，通过准确可靠的数值分析工具，对载荷变化规律与物理本质的研究有助于设计者找到提升直升机性能的有效途径。 小速度前飞、大速度前飞以及重载飞行是直升机出现高振动载荷的典型飞行状态。本文针对这些工程关
2、注的飞行包线中的重点与难点部分，对旋翼振动载荷预估与分析问题展开研究，完成了以下几个方面的工作： 1. 综合气弹分析方法的动力学建模 采用 Leishman-Beddeos 二维非定常/动态失速模型计算桨叶气动力， 由自由尾迹模型计算桨盘诱导入流，建立了基于柔性多体动力学思想的旋翼系统动力学模型，发展了一种工程实用的配平迭代计算方法，并由此获得旋翼载荷。 2. 典型飞行状态下旋翼振动载荷计算与分析 以 SA349“小羚羊”直升机为算例，首先计算了一个小前进比和一个大前进比两种典型状态的载荷。结果表明，本文对这两种稳态前飞状态的计算与试飞测试数据吻合很好，与国际著名的 CAMRADII 软件的计
3、算精度相当，验证了建模及计算方法的有效性。随后，将计算范围延伸到接近飞行极限的高速转弯、高桨盘载荷状态，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。最后，通过计算结果与试飞测试数据的对比，总结了桨叶气动载荷、振动载荷的变化规律，并得到一些有益的结论。 3. 旋翼铰链力矩研究 以典型条件下 SA349/2“小羚羊”直升机铰链力矩计算结果为基础，将计算扩展到其他飞行状态，并结合飞行测试数据与其他机型测试及计算的相关结果，研究铰链力矩的变化规律与影响因素。 关键词：关键词：直升机，旋翼，气动弹性，振动载荷，铰链力矩 旋翼振动载荷计算与分析 II ABSTRACT Complex flow
4、 environment and various coupling effects have made the rotor load prediction a tough problem to tackle. Prediction of rotor laods is the key issue for rotorcraft design. On one hand, in both the conceptual design and the detail design, accurate prediction of rotor loads can effectively cut down des
5、ign cycle, save the experimental cost and avoid project rist. On the other hand, by using precise and reliable numerical analysis tools, the study into the laws and physical essence of rotor loads can help the designer find effective ways of improving helicopter performance . Low speed flight,high s
6、peed flight and high thrust flight are the typical flight regimes that rotor encounter high vibration loads.These conditions are the key and also difficult part that the engineer concern in the flight envelope.This paper investigates rotor vibration loads in the typical conditions Several works are
7、present as follows: 1. Dynamics model of rotor system A comprehensive analysis based on flexible multibody dynamics method is used to model rotor system. Leishman/Beddoes 2D unsteady/dynamic stall model is incorporated and used to calculate rotor blade section airloads. The inflow is evaluated with
8、the free wake analysis.Rotor loads are obtained by trim procedure. 2. Prediction and analysis of rotor loads in typical flight regime SA349/2 “gazelle“ helicopter is used as the sample in this paper. Rotor loads calculation has been carried out in typical forward flight regime, including transition
9、speed、high speed and steady turn. For steady forward flight, the results correlate well with the test data, and have comparable precision with CAMRADII. For steady turn, analysis captures main characteristics of rotor loads caused by dynamic stall. Several laws of rotor airload and balde vibration l
10、oad are obtained from both calculations and flight test data. 3. Investigation of rotor pitch link load Based on the accurate prediction of sample helicopters pitch link load in the typical regimes, calculations are extended to other flight conditions. laws and the influence factors of pitch link lo
11、ad are studied by using flight test data and calculation results of sample helicopter and other conventional rotorcraft or rotor models. Keywords: Helicopter,rotor,aeroelasticity,vibration load,pitch link load 南京航空航天大学硕士学位论文 V 图、表清单 图 2.1 桨叶弹性变形 . 11 图 2.2 桨叶参考截面转动 . 11 图 2.3 旋翼坐标系统 . 12 图 2.4 递推算法流程图 . 16 图 2.5 非线性梁单元 . 17 图 2.6 铰接式旋翼模型 . 17 图 2.7 旋翼/传动系统耦合建模示意图 . 17 图 2.8 剖面气动力计算流程图 . 22 图 2.9 剖面迎角与气动力 . 25 图 2.10 桨叶运动方程求解流程 . 29 图 2.11 旋翼载荷计算流程 . 30 图 3.1 SA349/2 直升机测试飞行包线 . 33 图 3.2 SA349/2 桨叶负扭转分布 . 34 图 3.3 SA349/2 桨叶形状、翼型配置、压力传感器分布 .
