基于最大似然法的风洞自由飞试验气动力参数辨识技术研究

采用最大似然辨识算法对风洞自由飞试验数据进行气动力参数辨识,可以避免直接对测量数据进行二阶数值微分造成的气动参数的严重误差。详细介绍了风洞自由飞试验气动力参数辨识的原理及方法,分别通过仿真和实测数据算例对方法进行了具体说明和实现。算例辨识结果表明将气动参数辨识技术应用于风洞自由飞试验,是获取飞行器气动特性的有效途径之一。力导数可辨识性较低,受测量精度影响较大;力矩导数辨识结果与工程软件计算值接近,相对误差在30%以内,基本满足工程精度要求。同时,增加试验数据测量点数、提高数据测量精准度、安装过载测量设备、提升模型加工工艺水平,均有利于提高辨识结果的可信度。

Research on aerodynamic parameter identification technology in wind tunnel free-flight test based on Maximum Likelihood Estimation

Using the Maximum Likelihood Estimation method can avoid severe errors of aero-dynamic coefficients as a result of direct differentiating the measured data in wind tunnel free-flight test.This paper introduces the rationale and methodology of the aerodynamic parameter i-dentification technology in the wind tunnel free-flight test in detail.Simulation and test examples are presented.The identification results indicate that the aerodynamic parameter identification from wind tunnel free-flight test data is an effective method in study of aerodynamic characteris-tics of aircrafts.Although force derivatives are hard to identify,moment derivatives are easy to i-dentify and the identification results are close to the engineering results.Meanwhile,the increase of the number of sample points,the improvement of precision of measurements,the installation of overload measuring equipment and the improvement of machining level of test models are all favorable for enhancing the reliabilities of results.