Vortex control in a jet-mixing tank of automotive manufacturing

Chaotic recirculating flows in jet-mixing tanks can be controlled via vortex-jet interactions through topology modifications. For the case study of an automotive cleaning tank, the flow enters through an injection plenum and exits through a suction plenum. In Part 1, the diameter of the collector ports and the overall topology of the plenums were analyzed with computational fluid dynamics. Four configurations were compared: velocity, recirculation flow rate, and shear stress, which should be maximized to improve cleaning, and the vortice size, which should be minimized to uniformize impurities removal. For a parallelepiped tank, the best results are achieved with symmetric plenums and a collector close to the edge wall, behind the injectors. The collector should be positioned in the injector plane to enable a full circulation before the suction. The ports should have an angle of 90° to the injectors, easing the suction. The same flow rate must be removed by each port. It was possible to increase the velocity in 9%, the recirculation flow rate in 22%, and the shear stress in 36%. In Part 2, the cleaning was simulated with a car shell inside the best configuration. Compared to the original case, the velocities increased 30%, and the average shear stress increased 50%. Overall, it was shown that the jet-suction interaction is mainly responsible for the promotion of the recirculation flow rate, and collector modifications have a major influence on the suction system. The use of symmetry influences the size of vortices and flow uniformization.