Schlieren Visualization of a Shock Tube Flowfield

Schlieren imaging was used to visualize the shock wave that is produced in a shock tube with a square cross section of 1 sq. inch. The shock tube consists of a driver section and a driven section which is connected to a test section that has a 3-in diameter optical access. High speed video recording of the experiment was performed using a Shimadzu HPV-X2 camera. The shock tube setup has a total of 8 high-frequency response pressure transducers, with one transducer located in the driver section, five in the driven section, and two in the test section. The data from the pressure transducers were sampled at 2.5 MHz using a high-speed data acquisition. The data acquisition program was triggered when the first transducer in the driven section detected the shock wave passage. Simultaneously, a trigger signal was sent to start the high-speed camera recording. The camera recorded the optical field at a frame rate that was sufficiently high for capturing multiple images of the shock wave in the test section for time-of-flight velocity calculations. The experiments were run with a frame rate of 100,000 fps and an exposure time of 2 µs. The images from the high-speed video recording were then used to calculate shock wave velocity, which were corroborated by the shock wave time-of-flight calculations from the pressure transducers. Further information about the experiments will be provided in the full paper. This work is supported by NASA M-STAR under Grant No.80NSSC23M0208 with Prof. Liwei Zhang and Prof. Frank K. Lu as lead investigators. Additional funding was provided by the College of Engineering Research Experience for Undergraduates program. The high-speed camera used in this work was loaned by Prof. Andrew Makeev.