脉冲燃烧风洞测力系统动态标定方法

摘要

针对脉冲燃烧风洞中的测力系统,提出了一种动态标定方法.利用力锤在模型表面上不同位置,沿不同方向施加一系列集中载荷,由输入载荷和天平输出辨识出该表面对应的单位脉冲响应函数(UIRF),再将各表面对应的UIRF加权得到系统的UIRF,加权系数由试验状态下各表面的压力分布确定.辨识某表面对应的UIRF时,通过将其参数化使反卷积问题转化为参数优化问题以回避问题的病态特性.求解参数优化问题时,先用遗传算法搜索到参数全局最优解的近似值,再以此作为单纯形方法的初值继续优化得到参数最优值.在ANSYS中模拟了动态标定过程,考虑了实际试验中输出应变含有较大噪声的情况,验证了这种动态标定方法的准确性.%A new dynamic calibration method for a dynamometric system in impulse combustion facilities is proposed.The calibration involved uses an instrumented impact hammer to apply individual calibration forces in different directions at different positions on a face of the model and calculates the unit impulse response function (UIRF) of the face from input loads and output strains.UIRFs of different faces are weighted to obtain the UIRF of the dynamometric system and the weighting coefficients are determined by the pressure on each face under the experimental condition.By parameterization, the problem is converted into a parameter optimization problem to solve the UIRF.Using a genetic algorithm to obtain the approximation of the global optimal solution of the parameters and setting it as the initial value of a simplex algorithm, the exact solution is obtained by the simplex algorithm then.ANSYS simulation of the dynamic calibration is presented.Input loads and output strains are recorded and noises are added to the output strains to simulate the actual experimental situation.The simulation validates the accuracy and feasibility of the dynamic calibration method.