(552d) Validation of Cfd Models for a Microscale Confined Impinging-Jet Reactor Using Micro-Piv and Reactive Lif

Microscale confined impinging-jet reactors (CIJR) are well suited for many important chemical processes which require rapid mixing [1]. In this study, microscale particle-image velocimetry (micro-PIV) and reactive laser-induced fluorescence (LIF) are used to measure the flow statistics in a microscale CIJR, and the data are used to validate a CFD model for microscale turbulent reacting flows.

The geometry of the planar CIJR investigated is shown in Fig. 1. The width of the impinging jets, w, is 0.5 mm. Letting W, H, Z and δ represent the chamber width, height, length and the outlet width, respectively, their scaled values are W/w = 4.76, H/W = 0.8, Z/W = 1.2, and δ= 2w. The depth of the CIJR is 1 mm. The lengths of the inlet and outlet sections allow for fully developed flow at the exits. The jet inlet flow rates (same for both inlets) are carefully controlled with Reynolds numbers (Re) ranging from 800 to 2500 based on the inlet hydraulic diameter and bulk velocity. The images of the instantaneous velocity field are taken using a CCD camera with a spatial resolution of 51.4 by 51.4 μm². Our study shows that CFD model predicts the essential behaviour of the mean flow field with two recirculation zones above the impinging jets. The computed turbulent kinetic energy (TKE) is largest at the interface of the impinging jets. The zone of intense energy dissipation is limited to a T-shaped region. In order to validate the mixing model, scalars involved in a fast acid-base reaction will be measured using reactive LIF and compared with those predicted by micromixing models such as the two-environment direct-quadrature-mothod-of-moments (DQMOM) ? interchange-with-the-mean (IEM) model [2].

References:

[1] Johnson B. K., Prud'homme R. K. Aust. J. Chem. 2003, 56: 1021-1024.

[2] Liu, Y., Fox R. O. AIChE J. 2006, 52: 731-744.

[3] Johnson B. K., Prud'homme R. K. AIChE J. 2003; 49: 2264-2282.