TABLE OF CONTENTS Numerical simulations of transonic flutter and active control have been performed, by coupling independent aerodynamic and structural dynamic codes in the time domain. A simple control system has also been integrated with the coupled code, and since this requires perfect synchronisation of fluid, structure and control signal, the strong approach to coupling has been adopted. Two and three degree of freedom two-dimensional structural models have been considered. The consistency of the coupling has been demonstrated by considering the total energy of the structure and work done by the fluid. The difference between the two remains constant with time regardless of the structural motion.
The coupled scheme has been used to simulate time responses to structural disturbances for various Mach numbers and speed indices, to attempt to compute flutter boundaries for the two and three degree of freedom cases, and the results compare well with other published data. Furthermore, the structural model has been extended to include an actively controlled trailing edge flap, and this has succesfully been used to increase the stability margin by means of control surface motion. The aerofoil velocity feedback signal was found to give the best suppression results, and for the NACA64A010 aerofoil an increase of up to 19 per cent in the allowable speed index can be achieved within the transonic region. Furthermore, it has been shown that active control is still effective when there is free-play in the control hinge the aerofoil response is supressed to within the free-play region.
The...
