Recent work investigating excitation effects on an acoustically excited jet flow is reported. Emphasis is placed on integrated visualization and high-resolution and digital image processing, sequential planar gas concentrations and some characteristics of the large-scale vortical structures of acoustically excited jet flow, such as multiple-eddy merging, vortex-braids formation, eddy evolution and entrainment processes, jet-boundary expansion, etc. The digital image processing technique employed here extends our previous work (Chao et al. 1990) to optimal threshold filtering of the background noise and in situ calibration of camera and illumination distortions. A compact, low-cost, automatic frame acquisition and analysis system is developed for mean and r.m.s. planar gas concentrations and automatic jet-boundary identification. Also, stroboscopic images are created for detailed sequential study of a quick-changing process using a low framing-rate camera by suitably controlling the acoustic excitation frequency and the jet flow.
All Science Journal Classification (ASJC) codes
- 物理與天文學 (全部)