LARGE-EDDY-SIMULATION OF TURBULENCE STRUCTURES IN THE INJECTOR FLOW AND COMPARISON WITH SURFACE PERTURBATIONS OF TURBULENT FREE LIQUID JETS

Turbulence inside liquid jets emerging from the injector element into quiescent air is phenomenologically identified as being responsible for the development of initial disturbances at the jet surface. Therefore, the structure of turbulence in the injector flow and decay of turbulent scales in a pseudo free jet is computed using a threedimensional and time dependent Large-Eddy-Simulation scheme. Concentrating on computational results with regard to the near wall behaviour of turbulence inside the liquid, mean eddy lengths in the radial and axial direction as well as mean fluctuation velocities of these coherent structures are compared with experimentally observed mean amplitudes and wavelengths of surface disturbances respectively their rates of growth. Due to the quantitatively good agreement between numerical simulation and experiments, the hypothesis of turbulence being the reason for the primary destabilisation of the jet surface is supported and the mean development of these disturbances can be predicted [1].