Unsteady aerodynamics identification of transonic buffet by incorporating shock position

Transonic shock buffet is characterized by self-excited and large-amplitude oscillations of shock wave and the aerodynamics, resulting in reducing the handling quality and even causing flight accidents. Efficient and accurate prediction of the unsteady aerodynamic loads caused by the shock buffet, thereby, is an urgent and challenging work in the aeronautical engineering. With the sparse identification technique, an unsteady aerodynamic modeling framework is proposed to predict the shock buffeting loads over an airfoil. First of all, dynamic analysis reveals that the oscillating lift coefficient is strongly dominated by shock wave motion. With the sparse regression framework, an algebraic equation is, then, derived from the time series samples to parametrically describe the dynamic behavior of the shock buffet by incorporating the dynamical features of shock wave. By specific analysis of coherent structures with different frequencies, modeling can be achieved in both light and deep buffeting phenomena. The temporal response of the lift coefficient can be effectively predicted at varying Mach numbers and angles of attack with a relative error of less than 4%. This approach establishes a physics-informed function mapping between measurable shock wave dynamics and challenging-to-quantify lift forces, offering a potential solution for predicting aerodynamic force.