Rocket Noise Sources Localization Through a Tailored Beam-Forming Technique

Abstract

A source localization technique is applied to analyze wall pressure measurements undertaken on the surface of a space launcher mock-up. The technique is based on the combined use of a standard beam-forming technique and elementary acoustic solutions tailored to the space launcher geometry. Two classes of acoustic elementary solutions are considered: plane waves impinging on the surface of an in nite cylinder computed analytically trough a literature formula, and plane waves impinging on the real space launcher computed numerically through a computational acoustic technique. In both cases, the 3D acoustic eld resulting from the impingement of an arbitrarily oriented plane wave is obtained by a truncated series summation of elementary axial-symmetric solutions. These two classes of basis functions are proven to provide consistent source localization results in the addressed frequency regime. However, although the analytical functional basis enables a faster localization of the noise sources that take place during the rocket ring, the numerical functional basis is expected to enable, at an acceptable computational cost, a more reliable reconstruction of the acoustic loads on the space launcher surface in a higher frequency regime. The proposed CAA-based beam-forming and source reconstruction technique is therefore a useful tool for the vibro-acoustic design of future launch vehicles.