Flight effects on turbulent-jet wavepackets

Resumo

© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.A formulation to evaluate the mean flow field of an assumed jet embedded by an outer coaxial stream is used to extrapolate measured mean-flow velocity profiles from static to flight conditions. This velocity field was then input in a parabolized stability equations (PSE) model, based on the same code of Sasaki et al.18 (2015), in order to retrieve the wavepacket signatures of axial velocity fluctuations. Overall results are in good agreement with experimental measurements. There is an observed increase in wavepacket wavelengths and phase velocities. Also, axial amplification rates are determined and show stabilization in the near-nozzle region, which is confirmed by experimental power spectral densities on the jet centreline. This tendency holds as the free-stream velocity increases.