Numerical investigation of coaxial turbulent jet

Abstract

The paper presents a numerical study of a compressible and turbulent coaxial jet, using a Large Eddy Simulation type approach. This study focuses on the implementation of a high-performance and modern numerical method to meet the requirements in terms of results accuracy and calculation cost. The code was parallelized using the Message Passing Interface 'MPI' library. Inviscid fluxes are evaluated using a new linearization solver for the equations characteristic of approximate Riemann problem and the solution has been advanced over time using an explicit two-step McCormack method. The purpose of this study is to understand the initial stage of the transition process from laminar to turbulent flow in coaxial jets. Therefore, it has been determined that the first step in the transition process from laminar to turbulent flow in coaxial jets is initiated by the development of Helmholtz (primary vortices) in sheer layers, while three-dimensionalization turbulence is initiated in the second step with the emergence of secondary vortices. The transverse evolution of Reynolds tensors showed that the axial Reynolds tensor contribution is associated with primary instability while the transversal Reynolds tensor contribution is associated with secondary instability. Flow self-similarity state is obtained in fully developed turbulence region. Axi-symmetric mode predominates on each shear layer in the initial flow region. The results obtained are in good agreement with experimental results similar to this study's simulated jet.