Wind Tunnel Strain Balance Automatic Calibration Device Developed

Force tests are among the most commonly required test items in wind tunnel testing. The uncertainty and reliability of force test results are decisive for aircraft development. In force tests, strain gauge balance plays a key role, whose reliability and uncertainty can determine the outcome. Also, the uncertainty of force balance constitutes an important factor for force test uncertainty. When a balance is used to measure aerodynamic loads on a certain aircraft model, the uncertainty is dependent on not only the basic performance of the balance itself, but more importantly the accuracy of static calibration that is constrained by the performance of the calibration equipment and the related method for data loading and processing. That is the reason why aerodynamics researchers at home and abroad are highly concerned about the development of balance calibration equipment. To improve the accuracy of balance calibration and thereby the accuracy of force tests, the latest research achievements often are utilized in the course of development to establish high-precision, fully-automatic calibration systems. With respect to the development of such systems, High-Speed Aerodynamics Institute of China Aerodynamics Research and Development Center was endeavored to develop a six-component automatic balance calibration system without poise on the order of 30000N, so as to meet the requirement of ground calibration for balances used in its 1.2m Transonic and Supersonic Wind Tunnel, 2.4m Transonic Wind Tunnel and 2m Supersonic Wind Tunnel.Based on analyses and study of the working principle of strain gauge balances, the method was introduced in this paper for structural and electric design of the calibration system. Then the system structure, main performance and technical parameters were presented in detail, with an elaborate account of the major technical difficulties involved and the key solutions thereof. Also, the load uncertainties of the components of the calibration system were evaluated, the system performance was tested, and the static calibration results and aerodynamic parameter test results with different calibration rigs were compared. It was indicated by comparison that all the performance indicators of the new system have attained an advanced level in the world. Therefore, its application may assume great significance for upgrading force test accuracy in China as well as developing various civilian and military aircraft models, and high-tech strategic weapons.