Abstract
Objective in the present study is to examine effects of a horn attached to a circular nozzle on the coherent structures in the near field of an axisymmetric jet. Experiments have been conducted to compare two flow fields issued through a plate nozzle and horn nozzle in a water channel. Reynolds numbers of these flows were low enough to visualize the flow patterns with the dye-injection method and to capture the coherent structures by using an ultrasonic velocity profile (UVP) monitor. Images were reconstructed from the visualized photographs along the line of x/d=20, and from these images for the horn nozzle, a large scale structure was found out. Instantaneous velocity profiles were obtained in the radial directions with UVP, proper orthogonal decomposition was applied to these dataset.
