LDV measurements of well converged third order moments in the far field of a free turbulent round jet

Laser Doppler Velocimetry was used to study the far field of a turbulent round jet at high Reynolds numbers in a well controlled environment (ReD=1.5×105,Reλ=548 and x/D=30)x/D=30). Special care has been devoted to statistical convergence in order to obtain very smooth distributions of second and third order moments of velocity fluctuations. The V¯ and uv¯ distributions respectively satisfy the continuity and momentum equations, showing a much better agreement than what has been published previously. Despite the fact that the stationary hot wire (SHW) technique is known to not properly estimate the high order moments, it was shown that in the centerline region of the jet, third order moments can be obtained with a better level of accuracy than what has been reported. The present LDV database has also been used as a comparison reference for a novel conditional analysis of SHW limitations based on instantaneous incidence angle. It was shown that when flow events with angles outside the SHW sensitivity range are suppressed from the LDV measurements, v and w   second order moments tend to show better agreement with the SHW results. In the case of uv¯, this analysis led to a nearly perfect match between SHW and altered LDV data.

► LDV results in a turbulent round jet at high Re in a well-controlled environment are presented.
► High quality measurement with very good statistical convergence up to the third order moments.
► V and uv distributions remarkably satisfy continuity and momentum equation respectively.
► Stationary hot wire data show better agreement with LDV than what is found in the literature.
► SHW limitations are investigated using filtered LDV data based on instantaneous flow angle.