论文信息 - Laser-induced gas breakdown as a light source for schlieren and shadowgraph particle image velocimetry

Laser-induced gas breakdown as a light source for schlieren and shadowgraph particle image velocimetry

The "schlieren PIV" technique combines schlieren or shadowgraph optics with particle image veloci- metry PIV equipment to measure the velocities of turbulent eddies in flows with sufficiently strong changes of the refrac- tive index without actual particle seeding. Prior work on this technique used direct laser illumination that produced inad- equate schlieren image quality due to coherent artifact noise and other problems. By way of a simple equipment modifi- cation, we show the white-light emission of a laser-induced air or argon breakdown to be an improved light source for schlieren and shadowgraph PIV. The Nd:YAG illumination used in standard PIV is converted to a white-light pulse by this means. High-quality schlieren images are obtained and measurements in a helium jet using this new approach com- pare well with previous data. The method is especially appli- cable to high-speed flows requiring time delays of 5 so r less between the images of a PIV pair. © 2006 Society of Photo-

Gary S. Settles | Jason Volpe

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