Numerical analysis of the gas-assisted laser cutting flow from various supersonic nozzles

In the present paper, the exit jet patterns from four different supersonic nozzles have been numerically simulated using OpenFOAM (R) Computational Fluid Dynamics (CFD) toolbox. The desired-design operating condition, for each of these nozzles, has been calculated using quasi 1-D gas dynamics theory. Mach number and pressure distributions are presented for each nozzle to illustrate the effect of both the nozzle geometry and the operating conditions on the behaviour of the exit jet. Then, the predicted numerical results have been validated by comparison with the experimental measurements reported in previous literature. As main outcomes, the simulations results are quantitatively in high agreement with the reported experimental observations. The correlations between jet flow stability and divergence angle are discussed and the effect of Mach number and exit diameter on the jet divergence are presented.