Burst-mode velocimetry of hypersonic flow by nitric oxide ionization induced flow tagging and imaging

This Letter describes, to the best of our knowledge, a new approach to flow tagging, nitric oxide (NO) Ionization Induced Flow Tagging and Imaging (NiiFTI), and presents the first experimental demonstration for singleshot velocimetry in a near Mach 6 hypersonic flow at 250 kHz. The mean velocity of 860 m/s was measured with a single -shot standard deviation of as low as 3.4 m/s and mean velocity uncertainty of 5.5 m/s. NiiFTI is characterized by a long fluorescence lifetime of nitrogen with 1e decay of approximately 50 mu s measured in air. The method relies on a single nanosecond laser combined with a high-speed camera, creating an opportunity for the utilization of a typical nitric oxide (NO) laser -induced fluorescence (LIF) experimental setup with minor modifications as well as pulse -burst lasers (PBLs) for ultrahigh repetition rates. (c) 2024 Optica Publishing Group