B-19 マイクロジェット噴射による超音速ジェット騒音低減に関する実験(空力IV,一般講演)

概要

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Active noise reduction is one of the key technologies for future subsonic and supersonic jet engines with environmentally-friendly as well as highly efficient characteristics. In the present study, an experimental study of active control on supersonic jet noise was conducted by use of microjet injection. The microjets were injected to the shear layer of the main jet through 44 small holes at the lip of a rectangular nozzle, from which the main jet of Mach number up to 1.5 was exhausted. Based on the measurement of far-field sound pressure, it was found that the jet noise was effectively reduced by several dB (in some cases up to 10 dB). The microjet affected not only the broadband noise but also the screech tone noise. The sound pressure level and the frequency of the screech tone could be changed by the microjet, though the mechanism of the change was not clarified so far.
公益社団法人日本ガスタービン学会の論文
2007-09-01