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为了准确反映直升机旋翼 /机体耦合系统的动稳定性 ,建立了旋翼 /机体耦合非线性动力学微分方程 ,在时域内求解微分方程得到各片桨叶的挥舞、摆振及机体的响应用以对系统进行数值模拟 ;为了获得系统稳定性的定量值 ,用快速傅立叶变换 (FFT)确定模态频率 ,用基于傅立叶级数的移动矩形窗方法得到模态阻尼。地面共振分析表明 ,时域分析与特征值分析结果具有良好的相关性 ,并与试验值吻合 ,从而验证了该方法的有效性。大总距时 ,用时域分析得到的模态阻尼与试验值吻合得更好 ,该方法可用于具有非线性减摆器的直升机旋翼 /机体耦合系统的动稳定性分析。
In order to accurately reflect the dynamic stability of the helicopter rotor / body coupling system, a rotor / body coupled nonlinear dynamic differential equation is established, and the differential equation is solved in the time domain to obtain the waving, shimmy and body response of each blade In order to obtain the quantitative value of the system stability, the modal frequency is determined by Fast Fourier Transform (FFT), and the modal damping is obtained by using the moving rectangular window method based on the Fourier series. The ground resonance analysis shows that the correlation between time domain analysis and eigenvalue analysis has a good correlation with the experimental data, which verifies the effectiveness of the proposed method. When the total distance is large, the modal damping obtained by the time-domain analysis agrees well with the experimental data. This method can be used to analyze the dynamic stability of helicopter rotor / body coupling system with nonlinear dampener.