Development of a Retro-Reflective Screen-Based Large-Field High-Speed Shadowgraph Flow Visualization Technique and Its Application to a Hydrogen-Fueled Valveless Pulsejet Engine

摘要

Large field flow visualization of the unsteady combusting flow inside a hydrogen-fueled valveless pulsejet engine has been successfully demonstrated by using a retro-reflective screen based high-speed shadowgraph technique. A rectangular cross-sectional valveless pulsejet engine with optical access has been designed, fabricated, and successfully used for demonstrating the effective use of a retro-reflective shadowgraph technique for large and spatially wide flow fields of interest. The aspect ratio of the engine considered for the study was 13.5 and the technique helped to understand the acoustically coupled combusting flow structures from the intake to the tailpipe of the pulsejet engine. A Photron FASTCAM SA4 camera was used in this study. High-speed shadowgraph videos were captured with a frame rate of 13500 frames per second with a resolution of 1024 × 272 pixels.