Turbulent Structure near the Stagnation Point of an Axisymmetric Impinging Jet

Abstract

The turbulent structure near the stagnation point of an axisymmetric impinging jet is investigated quantitively from the data of cross-correlation between pressure fluctuation on the impinged plate and velocity fluctuation at various points in a jet. The movement and collapse of a large eddy are traced from maps of maximum values of cross-correlations which show that a large eddy impinges on the plate and soon collapses. The eddy impingement on the plate produces a pressure fluctuation, and it induces a new velocity fluctuation near the wall. By comparing this result with the pressure pattern on the impinged plate visualized by holograpic interferometry, it is clarified that the spot and arc shaped patterns in the pressure visulization correspond to the impingement of large eddies and the induced velocity fluctuation respectively.