103 Effects of Swirl and Buoyancy on Mixing Characteristics of Confined Multi-Jet Flows

Abstract

Three-dimensional numerical simulation was conducted to examine the swirl and buoyancy effects on the mixing performance of baffle-plate-type confined multi-jet flows. From the authors' previous works, it has been proved that the baffle-plate-type confined multi-jet produces a high performance in the fluid mixing. Adding the swirl motion to the multi-jet flows, however, appeared to incur deterioration of the mixing performance. This tendency was more noticeable for larger swirl number cases. Buoyancy effect was negligible when its working direction was parallel to the central jet axis. In the case that the gravity force direction was tilted and possessed a certain angle with the central jet axis, on the other hand, an asymmetric pattern of flow and mixture fraction was obtained, and a very poor mixing performance was achieved. On the contrary, the buoyancy effect was more significant when the swirl was accompanied and a considerable influence was found even when the operating direction was parallel to the central jet axis.