Characterizing shockwave propagation in waveguides by Schlieren imaging

Shockwaves can localize mechanical energy into a confined space. To increase the localized energy density, waveguides could be used to focus and direct shockwaves. We study the interaction between a shockwave and a waveguide. Schlieren imaging can visualize shockwaves, but few attempts to acquire quantitative pressure values for shockwaves from Schlieren imagery exist in the literature. We used a high-speed camera in a Schlieren setup to study shockwaves in V- and C-shaped waveguides. The shockwaves were generated with a pulsed Nd:YAG Q-switched laser, focused into air, to generate a breakdown spark. The Schlieren images were calibrated against a lens. We show quantitative time lapse Schlieren images from within the waveguides.