Characteristics of Multitube Multishroud Supersonic Jet Noise Suppressor

A supersonic jet noise suppressor with 191 tubes and 191 hexagonal shrouds was investigated at jet Mach numbers of 1.4 and 0.71. Flow and acoustic data were obtained for the plain jet and various suppressor configurations. With 191 tubes the sonic location was decreased from 19 in. for an equivalent iT^-in.-diam. jet to approximately 1 in. The jets coalesced at approximately 1^ in. and the Mach number was 0.73, with an over-all sound power level reduction of 15.2 db from the plain jet and a thrust loss of 10.2%. By adding 6.0-in. multishrouds to the tubes, the over-all sound power level reduction was 20.4 db. The impact pressure fluctuations decreased as x~2 downstream of the peak location for all configurations. The calculated thrust loss for the tubes and 6 in. multishrouds was 20.8% and the measured loss was 26.7%. Multitubes with the 6.0 in. multishrouds decreased the sound power level by 9.4 db for a Mach 0.71 jet.