Balance calibration method based on modern design of experiments

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.