Aerodynamic study of annular jet by Proper Orthogonal Decomposition

摘要

The annular jet is an example of complex shear flow situations. Two axisymmetric shear layers, originating at the jet exit, one at the nozzle lip and the other at the centre body, eventually meet downstream or interact with each other. The main aim of this study is to observe and analyze the effects of active control using acoustic waves on an annular jet with a great diameter ratio (r= 0.91), in order to find a new way to reduce jet instabilities. This contribution discusses the application of Proper Orthogonal Decomposition to the P.I.V. (Particle Images Velocimetry) velocity fields of the initial zone of an annular jet. Acoustic waves are then applied on the annular jet with different frequencies (fundamental, first harmonic...). Measurements are conducted with a Reynolds number Re_(Do)=107800. Active control has already been used with round jets and has given promising results, but only a few studies have been conducted on annular jets in this field. This work will permit us essentially to have a better knowledge of annular jets and used the potential of Proper Orthogonal Decomposition for aerodynamic study.