DOI: https://doi.org/10.36347/sjet.2025.v13i07.008

Pages: 552-568

An axisymmetric inviscid numerical study is carried out to obtain free supersonic jet structures of underexpanded, perfectly expanded and overexpanded supersonic jets emanating from a convergent-divergent nozzle having a semi-divergence angle of 15o for exit Mach number Me = 2.20, 2.61 and 3.12, and nozzle exit to ambient pressure ratio of pe/pa = 1.54, 1.36, 1.09 and 0.45. Computer fluid dynamics results include flowfield visualizations of density and Mach contour, pressure distributions along centre line of free jets. Comparison have been made with schlieren photographs to locate Mach disc and shock cell lengths. They are found in good agreement with available experimental results. It is observed that the first shock cell length is a function of exit Mach number, but the second cell is a function of shock strength. Colour schlieren optical technique in conjunction with digital image processing algorithm is initiated to analyse free supersonic jet structure.