舰载飞机弹射起飞若干复杂动力学问题研究

During the catapult launch of the carrier-based aircraft, complex dynamics problems exist because of the large load and short time, as well as the movement of the carrier and the airflow disturbance. This project, which based on multi-body system dynamics, dynamic finite element, viscous fluid flow theory, and aerodynamic theory, establish many dynamic analysis models of the aircraft in the whole process of catapult take-off, including launch bar tensing, the sudden discharge of holdback load, catapult taxiing, fast-extension, and leaving from the carrier, in order to solve many dynamics problems such as the nose gear's vibration caused by the sudden discharge of holdback load, nonlinear stiffness and damping characteristics during the fast-extension process, the influence of airflow distribution and carrier's movement on aircraft's take-off, and aircraft-sea parameter adaptation during the catapult take-off. By doing so, a set of high precision aircraft catapult take-off dynamic analysis methods is established, by establishing aircraft-ship-air dynamics integrated model and analysis environment and analyzing the key parameters' influence on aircraft-carrier parameter adaptation characteristics based on the dynamic analysis results. The studies of the project base the dynamic foundation for designing aircraft's landing gear and catapult mechanism. It is of important guiding significance for making the safety criterion on aircraft's catapult take-off and China's development of a new generation carrier-based aircraft.

舰载飞机拖曳弹射起飞过程载荷大、时间短，且受航母运动、气流扰动等条件影响，存在复杂的动力学问题。本项目基于多体系统动力学、动态有限元、粘性流体力学和空气动力学理论，建立舰载飞机弹射杆张紧、牵制载荷突卸、弹射滑跑、起落架缓冲器突伸、飞机离舰等弹射起飞全过程动力学分析模型，系统解决牵制载荷突卸瞬间前起落架支柱振动、前起落架缓冲器突伸非线性动态刚度和阻尼特性、舰面气流和航母运动对舰载飞机起飞动力学影响规律、舰载飞机弹射起飞机舰适配性等动力学分析难题，形成一套高精度舰载飞机弹射起飞动力学分析方法，构建模拟真实环境的机-舰-气流动力学综合分析平台，研究获得满足弹射起飞安全准则的主要机舰参数的适配规律。本项目的研究将为舰载飞机起落架和弹射机构设计奠定坚实的动力学理论基础，对制定舰载飞机弹射起飞安全准则、发展我国新一代弹射起飞舰载飞机具有重要的指导意义。

舰载飞机弹射起飞和拦阻着舰是决定飞行安全的重要环节，起落架作为舰载飞机起降过程中直接与航母接触的部件，是舰载飞机安全起降的重要保障。由于舰载飞机起降环境复杂，在试验中真实还原起降工况的代价相当大，且试验效果难以保证，因此开展舰载飞机起落架全面的理论研究具有重要意义，有助于缩短设计周期和降低试飞成本。.采用第一类拉格朗日方法建立了舰载飞机六自由度偏中心定位弹射起飞多体动力学模型。分析了舰载飞机偏中心定位弹射过程中飞机机身和起落架部件的动态响应，讨论了初始偏心距离、起飞质量以及弹射杆长度对弹射过程中飞机姿态运动以及起落架载荷的影响。.将舰载机弹射释放过程分为弹射张紧和牵制释放两个阶段，分别建立了描述舰载机机身及起落架在弹射力和牵制力综合作用下的动力学模型，给出了计算起落架与机身铰接点以及斜撑杆轴向载荷的方法。研究表明：牵制杆的长度直接影响牵制载荷突卸后前起落架的振动特性，提出了减弱前起落架振动现象的理论方法。.建立了高压气塞式变油孔双腔缓冲器系统动态特性模型，模型中分别考虑了高压气腔和低压气腔的空气弹簧力非线性指数，以及孔针式主油腔节流阀和密集孔式侧油腔节流阀的阻尼特性。综合弹射突伸与拦阻着舰两个方面的要求，制定了前起落架的优化目标，采用ISIGHT软件对其油针形状与回孔面积进行了优化。设计了三种舰载飞机前起落架突伸装置，并重点研究了前起落架高压充气突伸模式对起落架载荷和飞机弹射起飞动态响应的影响.在舰载飞机弹射起飞动力学模型基础上引入航母运动模型，推导了考虑航母运动的舰载飞机弹射起飞动力学模型，讨论了航母纵摇、横摇和垂荡运动下，不同初始相位对弹射过程中飞机的姿态运动及前、主起落架载荷的影响并分析了其动力学成因。