INNOVATIVE DEVELOPMENTS AT THE NTS ACOUSTIC REVERBERANT CHAMBER

摘要

For large aircraft and aerospace structures that will be exposed to typical jet noise of 135 dB Over-All SoundrnPressure Level OASPL for tens of thousands of hours it is necessary to consider the conventional accelerated acoustic testingrnat 164 dB OASPL for a shorter times of up to 1 hour in a large reverberant acoustic chamber. This paper describes thernlargest such available chambers, wherein NTS is one of the few large chamber facilities that can attain 165 dB OASPL.rnWith the advent of aerospace planes that experience >165 dB OASPL for their flight time, it is necessary to considerrnhow to upgrade the available sound pressure level to the higher OASPL and also how to extend the SPL available at thernmuch higher frequencies above 8,000 Hz. NTS has patented and used the Oscillating Supersonic Shock Generator to providernthe higher SPL at each of the frequency bands…and also in a specific narrow band of interest to a specific structuralrnresonant frequency.rnWith the advent of the brand new family of Pulse Detonation Engines, there is going to be a need to study the effectrnof the very low frequency bands below 60 Hz, where a much higher SPL will be required. NTS has designed a pulsed acousticrnsource to meet these needs, and it is described herein.