直升机悬停纵向运动模态的耦合

针对直升机运动模态内状态量间的耦合，提出了一种定量分析方法.该方法基于解耦得到的运动模态，结合气动导数矩阵，定量描述运动模态内状态量间的耦合，通过耦合的瞬时特性和积分特性定量区分各耦合.以Lynx，Bo105和Puma直升机为例，分析了三者悬停纵向运动模态的耦合特性.分析表明，纵向线速度通过空速稳定性对俯仰角速度的耦合作用在不稳定的悬停纵向振荡模态中起重要作用.基于算例的定量分析，筛选主要耦合得到简化模型，因此得到的运动模态固有频率和阻尼比的偏差小于2%，优于文献中的简化模型，说明了通过定量分析得到简化模型的可行性. 

Couplings in helicopter hovering longitudinal motional modes

A quantitative analysis method was put forward, concentrating on couplings among state variables in helicopter motional modes. In the method, based on motional modes resulting from a decoupling procedure, couplings among state variables in motional modes were quantitatively described in combination with the matrix of aerodynamic derivatives. And all couplings were distinguished quantitatively by instantaneous characteristics and integrated characteristics. With the application into helicopters, Lynx, Bo105, and Puma, coupling characteristics of hovering longitudinal motional modes were analyzed. It showed that the coupling on pitching rate from longitudinal velocity by speed stability played a vital role in the unsteady hovering longitudinal oscillatory mode. Based on the quantitative analysis of examples, simplified models were obtained with the selection of main couplings, and the resulted deviation of natural frequency and damping ratio of motional modes was less than 2%, superior to simplified models in references. So it is feasible to obtain simplified models on the basis of the quantitative analysis.