Numerical Study on Mixing Characteristics of Circular and Non-Circular Jets

The study of non-circular jet flows has become important due to their various applications, such as aircraft exhaust, combustion chambers and injectors.The present paper examines the impact of elliptical, square, and triangular-shaped orifices on the mixing characteristics of a free jet with Mach number 0.8.Numerical simulations using an SST K-ω two-equation turbulence model were conducted with a Reynolds number of 3.46×10⁵ for all cases.The mean velocity, decay rate, half-velocity width, spread rate, and turbulence intensity of the jet were analysed.The results showed that the triangular orifice provided the best mixing efficiency, with a shorter jet core length.The decay rate was found to be lowest for the square jet and highest for the triangular jet, which matches the previous research.The asymmetric jets experienced two axis-switching points, while the square jet experienced a 45⁰ rotation of its axes but no axis-switching.The core region had lower turbulence levels, while the highest turbulence levels were in the shear layer.