Abstract:
To meet the stringent demand for the precision and accuracy in wind tunnel force testing of large aircraft models, Aerodynamics Research Institute of AVIC (Aviation Industry Corporation of China) has innovated several cutting-edge force measurement techniques tailored for the 2.4 m continuous transonic wind tunnel. These techniques include a high-strength and low-thermal-expansion-coefficient balance with the temperature compensation and correction, an attitude angle measurement method using angle sensors and video and a modified method for measuring the attitude angle superposition, a fast calculation method of the initial balance loads under various test conditions based on the linear regression, an active anti-vibration technique based on front and rear damping systems that broadens the range of attack angle, video measurement and CFD (Computational Fluid Dynamics) simulation integrated elastic deformation correction method that effectively isolates the effects of elastic deformation on the aerodynamic forces in high-Reynolds-number tests. This paper delves into the principles underlying these innovative testing techniques and demonstrates their efficacy through case studies. Compared to the European Transonic Windtunnel, our techniques have achieved remarkable improvements in accuracy, with deviations of lift and drag coefficients for a large aspect ratio civil aircraft model being only 0.002 and 0.0002, respectively. These advancements represent a significant step forward in ensuring the reliability and accuracy of wind tunnel testing for large aircraft models.