Abstract:

Severe acoustics loading, which occurs during the flight mission of launch vehicles, is often responsible for damage to the payload inside the fairing compartment. The prediction of the acoustic loads on the payload fairing generated by large propulsion devices requires the use of analytical and numerical methods to identify the acoustic sources and the spectrum of the acoustic loads. The work presented in this paper investigates the nature of the external acoustic pressure excitations on the fairing in the low-frequency range of 50 to 400 Hz during the liftoff of a launch vehicle. The acoustic pressure excitation acting on a representative small launch vehicle fairing was estimated from the complex acoustic field generated by the rocket engine exhaust gases. The estimation procedure involved the use of a nonunique source allocation technique, which considered acoustic sources along the rocket engine exhaust flow. Numerical and analytical results for the acoustic loads on the fairing agree well.