Study on high-pressure hydrogen leakage characteristics under different shapes of nozzles.

In this paper, numerical simulations and experimental methods are utilized to investigate the near-field jet structures and far-field concentration distributions after the release of circular, equilateral triangular, square, and rectangular (AR2, AR4, AR8) nozzles. For all nozzle shapes, the hydrogen concentration along the jet centerline is inversely proportional to the distance from the nozzle. Circular nozzles exhibit the slowest decay of hydrogen concentration along the jet centerline, while rectangular nozzles show the fastest decay. Under the studied pressures, the concentration distributions along the jet centerline after the release of all nozzles are summarized into an equation. For the near-field jet structure, all nozzle except the circular nozzle experience varying degrees of deflection. When the aspect ratio is greater than or equal to 4, the Mach disk cannot be formed. An empirical formula for the position of the shock waves of the rectangular nozzle jet is proposed. [Display omitted] • AR8 nozzles exhibit the fastest decay of concentration along the centerline. • The concentrations along the centerline are summarized into an equation. • All nozzles except the circular nozzle experience a deflection phenomenon. • When the aspect ratio is greater than or equal to 4, the Mach disk cannot form. [ABSTRACT FROM AUTHOR]