Flow Field and Turbulence Characterization of a Counter Impinging Jet Reactor Using Particle Image Velocimetry

We characterize the three dimensional structure and quantify turbulence quantities in a counter-impinging jet reactor with trapezoidal cross-section to test the feasibility of achieving stratified mixing. Dye flow-visualization and particle image velocimetry (PIV) velocity field measurements are made in the inlet section of the reactor. Two-component velocity measurements are made on three sets of orthogonal planes for Re_j = 1000, 1800, 2600, and 3700; the overall structure of the flow field is found to be qualitatively similar for the Reynolds numbers studied, but the precise trajectory of the mean flow is found to be sensitive to inflow boundary conditions. Reynolds stresses and anisotropic invariants are calculated; the turbulent kinetic energy decreases linearly with increasing distance downstream in the reactor and it decreases at the same relative rate for all Reynolds numbers studied; anisotropic invariants and Reynolds stress maps indicate a turbulent stress state that tends toward isotropy downstream of the inlets. Turbulent stress maps indicate that the Reynolds stress components are stratified in the reactor channel, becoming uniform as a function of z by y/D_h = 4.