Numerical and Experimental Investigation of the Turbulent Flow and Mixing in a Static T-Mixer

Turbulent mixing plays an important role in chemical engineering, especially when the chemical reaction is fast compared to the mixing time. In this context a detailed knowledge of the flow field, the distribution of turbulent kinetic energy (TKE) and its dissipation rate is important, as these quantities are used for many mixing models. For this reason we conduct two direct numerical simulations (DNS) of a confined impinging jet reactor (CIJR) at Re = 500 and Sc = 1, with and without modelling the feeding pipes. The data is compared with particle image velocimetry (PIV) measurements and it is shown that only the simulation which includes the feeding pipes gives the correct flow field. This flow field is dominated by a stable vortex in the main mixing duct. High intensities of turbulent kinetic energy and dissipation are found in the impingement zone and decrease rapidly towards the exit of the CIJR. In the whole CIJR the turbulence is not in equilibrium. The mixing of the scalar is rapid in the impingement zone, but due to the fast decrease of the turbulent intensities and due to the relaminarisation of the flow the PDFs of the scalar distributions in cross sections of the CIJR take a bimodal form after the impingement zone.