Cavitation Dynamics in Wakes Behind Bluff Bodies

The shedding frequency of cavitating wakes behind bluff bodies depends strongly on the extent of the cavitation in the near wake. As the extent of cavitation increases from inception to an attached super-cavity, the wake shedding frequency attains a peak. The physical mechanism responsible for these observed changes in shedding dynamics with the extent of the wake cavitation is yet to be fully understood. In the current study, we employ time resolved X-ray densitometry and high-speed videography to study the cavitation dynamics in the wake of a triangular, nominally two-dimensional wedge in a re-circulating water tunnel to understand the underlying mechanisms responsible for cavity formation and shedding. It is proposed that alteration of the near wake dynamics by cavitation and the effect of compressibility in bubbly wakes that can explain the observed change in shedding dynamics. This hypothesis is tested via injection of non-condensable gas into the near wake of the bluff body.