Non-steady roll moment modeling for hypersonic lifting configuration

Thorough study of lateral stability of hypersonic lifting aircrafts needs exact expression of aerodynamic roll moment. Spectrum analysis is carried out using roll free-oscillation wind-tunnel test data, and a mathematical model of roll moment is proposed as an expression by the sum of the cosine of the main frequencies from spectrum analysis. The roll test curves of hypersonic lifting model present non-linearity, non-steady and periodical characteristics, and the results of spectrum analysis of roll vibration data under several different flow conditions show that they share three main vibration frequencies apart from the mechanical vibration frequency, which indicates that there are three scales of lateral separation or transition in the flow field. Comparison of the mathematical model of roll moment constructed with the corresponding aerodynamic test data indicates, this model can capture the primary tendency of test curves, and cover the main magnitude domain of roll aerodynamic moment. The mathematical model gives prominence to the multi-scale and periodical characteristics of lateral flow field of hypersonic lifting model.