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Japan Aerospace Exploration Agency

Acoustic analysis technology for improving the noise environment inside aerospace vehicles

The roar of a rocket launch creates vibrations that travel all the way to the spacecraft inside the fairing at the tip of the rocket. In order to safeguard these meticulously assembled spacecraft, engineers need to find ways to prevent unnecessary vibrations from affecting launch procedures. The same principle applies to aircraft, as well: keeping the cabin quiet requires a reduction in the sound generated by vibrations. We are therefore studying numerical prediction approaches to analyze sound-induced vibrations in structures, and the transmission of sound into structures.

Sounds include components of many different frequencies. In fact, there are respective numerical prediction tools for low and high frequency sounds. However, there is no established method for performing precise analyses of frequencies between these two extremes. Hence, we are concentrating on the wave-based method, which makes it possible to precisely analyze a wide range of acoustic vibrations with relatively simple geometry - from low frequencies to mid-frequencies. To make the method more widely applicable, we are thus researching a hybrid finite element-wave based method for the more complex geometry.

We are also studying the numerical prediction approaches of sound sources and propagations (nonlinear acoustics) for practical aerospace applications (e.g. launch site design and sonic boom reduction for supersonic aircraft, etc.). Our aim is to upgrade the respective technologies in order to attain the world’s most advanced high speed and sophistication levels, and to develop an integrative numerical prediction tool that accommodates the seamless application of technologies.

Simulation example of sound transmission through payload fairing w/ and w/o spacecraft

Simulation example of aircraft cabin noise (sound pressure level)