Development of Focused Schlieren Based Seedless Velocimetry for Boundary Layer, Transition, and Wake Studies

摘要

The objectives of the proposed research are (1) to develop a focused schlieren optical system for laboratory-scale demonstration for spray and combustion studies, (2) to develop new data processing techniques for obtaining velocity field, and (3) evaluate field-of-view, depth-offocus, and image resolution issues. Experiments were performed to visualize and measure velocities in a gas flow with liquid droplets. The experiments used a focusing schlieren optical system to visualize the refractive disturbances of the gas flow in a narrow depth of field. The images were recorded with a high-speed digital video camera for allowing PIV processing to identify velocities in the field of view. The high-speed images were processed to identify motion between frames to obtain velocity vectors. The processing currently picks up both the turbulent structure motions along with the water droplet motion. Future work involves developing methods to separately measure the particle and gas stream motions.