Numéro : 2061 - Year : 1988
Helicopter noise summary
R.LEGENDRE, Ingénieur Général de l’Armement ( G.M.), Membre de l’Académie des Sciences, Vice- Président de l’ATMA.
It is first underlined that the turbulence si9nificant for noise must be located relatively to moving axes, following the local flow.
The neighbouring eddies interact, stretching each other with a significant density change, which is the noise origin. The rotor noise is almost independent and is first analysed ; then the rotor blow strikes all the other parts of the helicopter, with a new and strong eddy stretching, creating and important noise source.
The main difficulty is the study of the interaction between the main and tail rotors