Formation, interaction and destruction of coherent structures play an important role in the propagation of a coherent beam through the environment and the occurrence of optical aberrations. The issues related to modelling of aero-optical effects in a turbulent jet and free shear layer are considered. A semi-empirical model designed to study the distortion of the phase function of the coherent beam, induced by turbulent flow fluctuations, is developed. Large eddy simulation of flows in a turbulent jet and free shear layer is performed. Unsteady turbulent flow of viscous compressible gas is described by the space-filtered Navier ? Stokes equations, closed with equation of state of a perfect gas and the RNG sub-grid scale model. The results of calculations with the vortex model and numerical results obtained are compared with each other, and with the experimental data and the data computed with the Reynolds-averaged Navier ? Stokes equations.
|
