Feasibility of helium and nitrogen as surrogate gases for hydrogen jet using planar laser-induced fluorescence in a constant volume chamber

This study investigates the feasibility of using helium and nitrogen as surrogate gases for visualizing the non-reactive behavior of hydrogen jets in a constant volume chamber. Hydrogen, helium, and nitrogen were individually mixed with acetone vapor and injected using a hollow-cone injector. The fuel distribution was visualized using Planar Laser-Induced Fluorescence (PLIF), while simultaneous Schlieren imaging was employed to capture overall jet structures. Quantitative comparisons of jet areas extracted from both imaging techniques demonstrated that acetone effectively followed the gas-phase flow of each species, validating its use as a flow tracer. Furthermore, helium and nitrogen exhibited jet dispersion patterns comparable to those of hydrogen across varying ambient pressure conditions, confirming their potential as optical surrogates. The findings suggest that non-reactive surrogate gases can be reliably used for safer experimental investigations of hydrogen injection phenomena, offering a valuable methodology for future optical diagnostics in hydrogen research. • Hydrogen jet creates a toroidal vortex ring due to pressure difference between outside and inside of jet • Ambient pressure affects jet structure, especially jet width. • Acetone-PLIF has feasibility to follow hydrogen jet structure without slippage. • Helium and nitrogen also create toroidal vortex rings due to pressure difference, but in different magnitudes. • Helium is more suitable to mimic jet structure due to its ability to simulate toroidal vortex ring.