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进气道动态特性的小偏差封闭传递矩阵模型仅能得到频率特性数据,为了获得多项式形式的传递函数,提出了一种基于MATLAB的计算方法。基于频域辨识获得了结尾激波对放气量扰动的有理多项式传递函数近似模型,此模型的频率特性与原始频率特性吻合较好,比Pade近似方法更简单准确。利用模型降阶方法对高阶多项式函数进行简化,获得了低阶传递函数,低阶模型与高阶模型的时域响应较为一致,为激波位置控制系统设计奠定了基础。分析了激波处相对面积变化率对频域特性的影响,结果表明相对面积变化率越小,激波运动的稳态距离越大。
The small deviation closed transfer matrix model of inlet dynamic characteristics can only get the frequency characteristic data. In order to obtain the polynomial transfer function, a calculation method based on MATLAB is proposed. The approximation model of the rational polynomial transfer function of the final shock to the deflation volume is obtained based on the identification of the frequency domain. The frequency characteristics of this model are in good agreement with the original frequency characteristics, which is more simple and accurate than the Pade approximation method. The model order reduction method is used to simplify the high order polynomial function, and the low order transfer function is obtained. The time domain response of the low order model and the high order model is consistent, which lays the foundation for the design of the shock position control system. The influence of the relative area change rate on the frequency domain was analyzed. The results show that the smaller the relative area change rate, the larger the steady-state distance of the shock movement.