Aero-servo-elastic analysis of a hypersonic aircraft

Abstract

Aero-servo-elastic analysis of a complex hypersonic aircraft is presented in this paper. A structure geometry was designed and built based on the X-43A vehicle. First, a three-dimensional structural finite element model was proposed with effective two-dimensional elements, which can obtain effective modal analysis results without useless local modes. Second, computational fluid dynamic (CFD) simulation was adopted to find aero-heating distribution of thermal mode via this structure. Aero-heating effect was included to study thermal-modal characteristics of the present structure. Influence due to material characteristic change and thermal stress was studied. After structural finite element analysis was completed, flutter of the present vehicle was investigated. Aero-servo-elastic analysis was then started from the definition of an aero-servo-elastic closed-loop system. In this system, the present aircraft is treated as flexible structure, in which the control sensor on the aircraft received not only rigid motion signal but also elastic vibration signal, and this signal can translate into the deflection signal to form aerodynamic control force through this aero-servo control system, and this force can continually influence aerodynamic force. One of the most important steps for this analysis was computation of unsteady aerodynamic force of the present structure, and the related process was developed based on an effective fitting method. Finally, bode diagrams of pitching, rolling and yawing were investigated, form which the law of aero-servo stability of the X-43A vehicle can be observed and analyzed. It can be found from the results of this paper that effective investigation of aero-servo-elastic characteristics of a complex hypersonic aircraft should be based on accurate structural finite element modeling, modal analysis and flutter analysis. The proposed method in this paper can provide effective analysis process for the design of controller for hypersonic aircraft.