倾转旋翼机变型、变速运动机理及变化规律研究

The tiltrotor aircraft combines the capabilities of helicopter vertical takeoff and landing and fixed wing aircraft high forward speed and range. These capabilities need the transition from helicopter flight mode to fixed wing aircraft flight mode by rotor dynamic tilting motion. The transition is a kind of motion with the variations of configuration and speed which operates within the conversion corridor, and still the challenge in the flight dynamics of tiltrotor aircraft. The project develops a methodology of the analyses for high resolution and precision rotor wake distortion as well as the rotor/wing aerodynamic interaction during the rotor dynamic tilting motion. Then a new ground test method to simulate the matching of lift and propelling force during the transition is presented, and an advanced flight dynamic model which can accurately predicted the flight characteristics within the conversion corridor is established. Furthermore, the behaviors of tiltrotor aircraft motions within the conversion corridor are revealed. Finally,the mechanism and characteristics of the effects of rotor wake distortion, viscous dissipation as well as rotor/wing aerodynamic interaction on the behaviors of tiltrotor aircraft motions during the transition are explored. The contribution of the project is to provide theoretical references for the design of advanced flight control law during the transition.

倾转旋翼机兼具直升机垂直起降和固定翼飞机快速巡航能力，要求通过旋翼动态倾转进行直升机模式与固定翼飞机模式之间的变换，这种变换是一种变型、变速运动，仍是当前倾转旋翼机飞行力学研究面临的难题。本项目发展旋翼动态倾转中的高分辨率、高精度尾迹畸变及旋翼/机翼气动干扰分析方法，提出旋翼动态倾转中的升力、推力匹配地面模拟试验方法，建立倾转旋翼机精细化飞行动力学模型，探索倾转旋翼机变型、变速运动中的飞行力学行为，揭示旋翼尾迹畸变、旋翼/机翼气动干扰等因素及其耦合效应对变型、变速运动中升力、推力匹配的作用机理与变化规律，为倾转旋翼机旋翼动态倾转过程的先进飞行控制律设计提供理论和依据。

项目研究了倾转旋翼机变型、变速运动机理及变化规律。.在旋翼动态倾转时的尾迹畸变及旋翼/机翼气动干扰研究方面，发展了一种旋翼动态倾转的非定常自由尾迹模型，构建了尾迹动态畸变与旋翼载荷瞬态特性之间的内在关系。发展出VTM/CFD混合方法模拟旋翼/机翼气动干扰，解决了数值模拟中多体相对运动信息交换和多维时间耦合问题，避免了数值模拟耗散对计算精度的不利影响。.在变型、变速运动的飞行动力学精细化理论建模研究方面，基于多体动力学理论，建立变型、变速运动中飞行器重心、惯性积等变化与惯性载荷的非线性变化效应分析模型；通过模型集成，形成了能准确反映变型、变速过程中旋翼和机翼非定常气动力与结构和惯性复杂耦合的飞行动力学模型和数值求解方法。.在试验研究方面，进行旋翼动态倾转指令条件下的变型、变速运动机理试验研究，采用六分量天平测量旋翼的升力、推力与俯仰力矩，采用激光片光流动显示技术对旋翼尾迹几何结构的动态畸变及旋翼/机翼非定常气动干扰进行流动显示，得到了旋翼动态倾转指令条件下旋翼尾迹畸变与耗散、旋翼/机翼非定常气动干扰等因素对升力、推力与俯仰力矩的影响。.在变型、变速运动的作用机理及影响规律研究方面，根据旋翼、机翼气动力匹配关系，发展出一种操纵混合模型，解决了直升机和固定翼飞机两种操纵方式共存而引起的操纵冗余问题，确保动态倾转过程中的升力与重力，推力与阻力及操纵功效平滑过渡，形成了倾转旋翼机倾的转过渡走廊以及变型、变速运动参数对倾转过渡走廊的影响规律。.结果表明本项目发展的旋翼动态倾转非定常分析模型能有效捕捉旋翼倾转过程中的尾迹畸变与旋翼/机翼气动干扰的动态特性；精细化飞行动力学模型能有效预测倾转旋翼机的倾转过渡走廊及变型、变速运动参数的影响规律。项目的研究成果从理论上解决了倾转旋翼机旋翼动态倾转过程的非定常气动分析、倾转过渡走廊的问题，可用于未来倾转旋翼飞行器的飞行动力学建模、飞行控制系统设计。