Study on assembly characteristics of an assembled wind tunnel balance with four triaxial-force piezoelectric sensors

Abstract

Wind tunnel balances are essential force measuring equipment for aerospace and other high-end equipment in wind tunnel test, which not only needs excellent static performance, but also needs good high-frequency response ability. An assembled wind tunnel balance and its calibration test system based on four triaxial-force piezoelectric sensors were designed according to the aerodynamic test requirements of an aircraft. The overall test system mainly consists of an assembled wind tunnel balance, calibration platform, vertical loading mechanism, lateral loading mechanism, standard force transducer and charge amplifier, data acquisition card, computer and acquisition software. The assembled wind tunnel balance consists of four high-stiffness triaxial-force piezoelectric sensors, upper/down plates and erection bolts. In response to the assembly issues of wind tunnel balances, the proposition was put forward that the preload torque of erection bolts would impact the measurement performance of the assembled wind tunnel balance. It is hoped to seek an effective approach to enhance the measurement performance of the wind tunnel balance starting from the structure itself. Based on this expectation, the measurement theoretical model and simulation three-dimensional model of wind tunnel balance were constructed, and the modal and static simulation analysis were also carried out. The performance calibration of four triaxial-force piezoelectric sensors was carried out, the overall scheme design of the measurement system was completed, and the test system of the assembled wind tunnel balance was built for the balance performance research. The influence of preload torque of different erection bolts on the measurement performance of the preload wind tunnel balance was studied, and the best preload torque suitable for the balance was explored to make the force measurement performance of the preload wind tunnel balance optimal. The static and dynamic performance of the test system meet the test requirements, with excellent linearity and repeatability, and the best combination of preload torque of the erection bolt was determined. The linear error of axial force was less than 0.258 %, and the linear error of torque was less than 0.562 %. The test proves that adjusting the preload torque of the erection bolts can effectively improve the static performance of the wind tunnel balance from the structure itself, which provides an effective new idea for scholars to study how to improve the performance of the wind tunnel balance. And, the first natural frequency of the wind tunnel balance was 1062 Hz, which was only 8.4 % different from the simulation result. It can realize the accurate measurement of the aerodynamics of the aircraft.