Análise aeroacústica de jatos coaxiais em regime subsônico

Abstract

The present work refers to a study of geometrical and velocity parameters of the ow, an their in uence on the noise generated by coaxial nozzles, similar to the ones used in modern aircraft engine. For this purpose, a methodolgy is chosen from a set of methods disposed within CFD++/CAA++ commercial code Metacomp Inc. Averaged equations coupled with a

uctuation synthesization model and the integral formulation of the Lighthill acoustic analogy are employed to calculate the noise spectrum and compare it to experimental data from JEAN EU Project. In the simulations, are made variations of the secondary to primary stream velocity ratio and the secondary to primary exhaust area ratio; the in uence of those parameters in the turbulence and noise are analysed. It was noticed: if the parameter increases the turbulence level, it does the same to the noise level. The noise spectrum was well computated into de range previously established (102 a 104 Hz), with dierence between the numerical and experimental levels is from 2 through 8dB s. In general, the trends pointed by the experimental data are also observed in numerical results, the lower the secondary to primary velocity ratio, and higher the area ratio are, the lower the related noise shall be.