机动飞行环境下转子系统的复杂非线性动力学行为及机理研究

Based on the prophase research of the nonlinear rotor dynamics during flight maneuvers in the doctoral dissertation of the applicant, this proposal is focused on the theoretical and experimental study at mechanism level. Taking the single rotor system as the research object, the motion equations of the system are formulated with the consideration of the maneuver loads with respect to the representative flight maneuvers, as well as the nonlinearities from the key components such as nonlinear elastic supports or roll bearings. By combining the general harmonic balance method with the alternating frequency/time domain technic, the theoretical method for solving dynamic equations with complex nonlinearities is proposed in this proposal, which can overcome the weakness of numerical methods in mechanism studies because of failing to obtain the unstable solutions. Then an intensively study on the nonlinear dynamic characteristics of different rotor systems during flight maneuvers is carried out by employing both theoretical and simulation methods, and the results are also verified with a series of experimental investigations. Furthermore, the proposed research intents to profoundly reveal the dynamic mechanism for how the complicated nonlinear behaviors of the rotor system occur during flight maneuvers, and how they are significantly affected by the system parameters. The motivation of this proposal is to initiate the progress on the fundamental theories for dynamic stability control of rotor systems in flight maneuvers. Moreover, a primary study is carried out in the field of dual-rotor system dynamics under maneuver load, which is aimed to generalize the research results from single-frequency-excited low-dimensional system to double-frequency-excited high-dimensional system.

本项目是对申请者博士学位论文的深化和扩展，在前期研究基础上进一步开展动力学机理层面的理论研究及实验研究工作。以单转子系统为研究对象，考虑支承、轴承等关键部件的非线性因素及典型机动飞行工况，建立机动飞行转子系统的动力学模型；引进现代数学方法中的时域频域转换技术对传统谐波平衡法进行改进，建立针对含复杂非线性因素转子系统振动方程的理论求解方法，从而突破数值方法由于不能求得系统不稳定解而无法深入开展动力学机理研究的限制；通过理论分析和数值仿真深入研究机动飞行环境下转子系统的非线性动力学特性，并采用实验手段对理论研究结果进行实验验证，深刻揭示机动飞行环境下转子系统复杂非线性动力学行为的发生机理以及重要工程参数的影响机制，以期为机动飞行转子系统的动力学稳定性控制提供理论指导；初步探索研究机动飞行环境下航空发动机双转子系统的非线性动力学特性，旨在将研究成果由单频激励的低维系统向双频激励的高维系统推广。

本项目围绕机动飞行环境下航空发动机转子系统的非线性动力学行为及机理展开研究，以期掌握飞机机动飞行带来的机动载荷对航空发动机转子系统动力学特性的影响规律，为机动飞行转子系统的动力学稳定性控制提供理论指导。提出了常数激励与简谐激励联合作用下转子系统非线性动力学特性的科学问题，并以Duffing系统及Duffing型转子系统为例研究了常数激励对系统骨架曲线、幅频响应特性及分岔模式的影响规律，研究方法及研究结果对深入认识常数激励在非线性动力系统中的本质属性具有借鉴意义。针对含间隙等复杂非线性因素的转子系统非线性振动方程的理论求解问题，引进现代数学方法中的时域频域转换技术对谐波平衡法进行改进，构建了半解析半数值的求解分析方法，突破数值方法由于不能求得系统不稳定解而无法深入进行动力学机理研究的限制，为深入开展机动飞行环境下转子系统复杂非线性机理研究奠定基础。通过研究深刻阐释了机动飞行转子系统碰摩故障下的亚谐共振分岔机理、机动载荷下含裂纹故障转子系统的超谐共振机理，并给出关键系统参数的影响规律，为机动飞行转子系统的动力学稳定性控制提供理论依据。提出了利用常数激励进行转子系统裂纹故障诊断的方法，并利用机动飞行转子系统实验台进行了初步实验验证，该技术已申请发明专利，为研究成果的转化应用奠定基础。针对实际航空发动机双转子系统开展了动力学建模和模型简化降维工作，为已有理论研究成果向实际航空发动机双转子系统的推广奠定基础。基于双转子-中介轴承系统简化动力学模型初步开展了主共振研究，重点探讨中介轴承间隙对系统非线性振动特性的影响，并初步开展了中介轴承故障机理研究，研究成果对中介轴承的设计、选用以及故障诊断有一定的指导意义。