June 2000
DOI:10.2514/6.2000-2026
Conference: 6th Aeroacoustics Conference and Exhibit
At lift-off, the jet noise of a launch vehicle produces a severe acoustic environment, and the loads induced by the acoustic pressure may damage payload and equipments. The more and more powerful launch vehicles, such as Ariane 5, involve an increase of the external sound pressure level. Consequently, the acoustic studies take a more important place during the development and the qualification of a large launch vehicle.
We present here studies dedicated to the noise reduction of the Ariane 5 launcher at lift-off on its launch pad in KOUROU (French Guyana) and carried out during the qualification phase. Two test campaigns have been realized with a 1/47 scale mock- up of the launch pad. The main objectives were to optimize the existing water injection devices and the launch pad geometry in order to decrease the sound pressure level inside the fairing.
The results lead to suggest modifications of the launch pad and the water injection device which could be efficient to reduce the sound pressure levels by several decibels. The transformations of the pad have been operational during the third and the fourth Ariane 5 flight.
The authors comment the whole experimental results obtained in the MARTEL facility and precise the methods used for the full-scale extrapolation. A comparison with the acoustic in- flight measurements is presented.