基于现代试验设计的风洞天平校准方法

Balance calibration method based on modern design of experiments

风洞天平的校准精度直接决定了风洞试验的气动载荷测量精度,为了提升天平校准的质量和效率,以BCS-100天平校准系统为研究对象,基于现代试验设计方法(modern design of experiments,MDOE)开展了风洞天平校准研究。针对单因子变量法(one factor at a time,OFAT)天平校准中存在系统误差与响应量耦合的问题,采用MDOE的随机、重复和分块策略控制校准的系统误差,并选定响应面理论的中心复合设计方法生成校准矩阵。校准矩阵共计86个样本点,包括64个分级因子点、12个轴向因子点和10个中心因子点,其中所有样本点的加载顺序做随机化处理,并作为一个样本块在短时间内集中完成加载,中心因子点则用于满足重复原则。最后开展了OFAT和MDOE的对比校准,拟合载荷的残差正态概率分布显示MDOE校准中横侧向分量的样本点独立性更强,样本点残差最高可降低84%;检验载荷显示MDOE和OFAT两种方法中天平所有分量的综合加载重复性持平,MDOE校准中横侧向分量的综合加载误差最高可降低54%。研究表明MDOE能够有效降低校准的系统误差,提升横侧向小量的预测能力。

The accuracy of aerodynamic force measurement in the wind tunnel test is dominated by the wind tunnel balance calibration.To improve the quality and efficiency of balance calibration,this work takes the BCS-100 calibration system as the research object,and proposes a calibration method for the wind tunnel balance calibration using modern design of experiments(MDOE).Aiming at the problem that the systemic error is coupled with the response in traditional calibration using one factor at a time(OFAT),the randomization,repetition and blocking strategies based on MDOE are used to control the calibration systemic error.The central composited design(CCD)based on response surface methodology is chosen to generate the calibration matrix,which is composed of 86 sample points in total,including 64 fractional factor points,12 axial factor points and 10 central factor points.The actual loading sequence of all the points is randomized,and the loading is completed in a short time as a single sample block,with the central factor points satisfying the repetition strategy.Finally,a contrastive calibration of OFAT and MDOE is applied in the calibration system.The normal probability distribution of the fitting load residuals for horizontal and lateral components shows that the sample points in MDOE have better independence,and the residuals can be reduced by 84%at most.The testing loads shows that both MDOE and OFAT have a similar comprehensive repetition error for all components,but the comprehensive loading error using MDOE can achieve an improvement up to 54%for the horizontal and lateral components.The present study indicates that MDOE can reduce the calibration systematic error effectively and has a better prediction capacity for small horizontal and lateral components.