Gust Response Alleviation with Model-Free Adaptive Control Method in Transonic Flow

In transonic flow, nonlinear problems due to shock waves could be induced by gusts, leading to difficulty in acquiring a relatively accurate aerodynamic model in the form of a state equation for gust alleviation, which is usually required for certain traditional control methods. In addition, using direct computational fluid dynamics (CFD) methods for simulation would be unacceptable for time cost when dealing with the control law design. A data-driven model-free adaptive control (MFAC) method is introduced to alleviate the gust response in transonic flow. The MFAC method transforms the control system into a dynamic linearized data model that exclusively uses input/output data, making the system more efficient. We investigated the influence of different gusts on the aerodynamic result for the rigid airfoil and the aeroelastic result for the elastic airfoil in a subcritical state in the transonic region. An unstable state with prominent fluctuating responses could be induced by certain types of gusts. By applying the MFAC method, the gust responses are remarkably reduced in all the study cases, and some unstable states are almost completely suppressed in certain cases.