Research on the Calibration Performance With Variable Loading Points of the Eight-Point Distributed Wind Tunnel Piezoelectric Balance for Measuring Aerodynamic Forces on Hypersonic Vehicles

The wind tunnel test balance of hypersonic vehicles is a crucial force measurement component for facilitating the aerodynamic optimization design of the aircraft. In response to the operational requirements of large-area loading, significant load application, and high-frequency excitation, an eight-point distributed wind tunnel piezoelectric balance (ED-WTPB) structure and its static calibration system have been proposed. Eight three-component piezoelectric force-measuring units (PFUs) are horizontally distributed within a long and narrow rectangular surface area. According to the point hypothesis theory and the force/moment balance theory, the mechanical model of the ED-WTPB is simplified, obtaining the relationship between the component forces received by each piezoelectric force measurement unit and the input force value, and determining the fundamental force measurement principle of the ED-WTPB. A 3-D model of the ED-WTPB is established, and finite element simulation analysis is performed using simulation software to verify the basic structural strength and calculate the inherent frequency of the ED-WTPB, ensuring that the proposed ED-WTPB structure satisfies the requirements of the wind tunnel tests for hypersonic vehicle models. Simultaneously, a static/dynamic calibration system for the ED-WTPB is designed. Through static/dynamic calibration tests, the static/dynamic performance of the ED-WTPB is obtained. The maximum linear error is 0.117%, the maximum repeatability error is 0.513%, and the first-order inherent frequency is 456.54 Hz. Both the static and dynamic performances meet the design requirements. In addition, variable loading point tests in different directions are carried out to obtain the static performance of the ED-WTPB under different working conditions, evaluating its measurement reliability and stability. The feasibility of the ED-WTPB is demonstrated, providing novel ideas for the design and manufacturing of large-sized wind tunnel balances.