AUTOROTATION AND THE THEORY OF BULLROARER SOUND

The present paper deals with a complete physical simulation of the sounding instrument called bullroarer and used by aboriginal tribesmen. The running of the bullroarer clearly involves aeromechanical aspects, closely related to the process of autorotation, as well as aeroacoustical aspects. The mechanical equations are solved in a first step, using computational fluid dynamics as a way- to deduce the unsteady aerodynamic moment and forces. Then the kinematics and the unsteady forces are used to calculate the radiated sound field, according to the acoustic analogy. Theoretical results agree well with experiments performed in an anechoi’c open wind tunnel. e