A Theoretical Investigation of Acoustic-Tubulent Interactions with Application to Free-Jet Spreading

摘要

Recent experimental investigations have demonstrated that applied acoustic waves of appropriate frequencies can change the spreading rate of a free turbulent jet or the reattachment location of a separated-reattaching jet. Several posible interactions are considered briefly. It is concluded that the observed effects in small turbulent jets can result from the direct interaction of the acoustic waves and the turbulent structure. The interaction of a monochromatic acoustic wave and a single harmonic vorticity fluctuation is considered first. The acoustic field is considered to be applied externally. The result shows significant changes of the steady or d-c vorticity when the eddy wave-number component of the vorticity fluctuation in the direction of sound travel equals the wave-number of the applied sound. Using Fourier transforms the result is extended to consider an entire spectrum of turbulent vorticity fluctuations. The spectrum is integrated to find the change due to the acoustic input of various turbulent parameters including the three-dimensional energy spectrum and Reynolds stresses. (Author)