Análisis de patrones turbulentos de un tanque agitado, utilizando dinámica de fluidos computacional y velocimetría por imágenes de partículas

Abstract

In the present investigation, the hydrodynamic behavior in the stirring tank was analyzed. Taking a special interest in the turbulent patterns derived from the generation of turbulent kinetic energy and its dissipation rate. As well as its variation when modifying the surfaces of a 45° pitched 4 blade turbine, when using U and V grooves. Measurements of the velocity fields were carried out with the technique of particle image velocimetry in different planes, with the aim of applying the methodology of angle resolved. The system consists of a double pulse laser with a wavelength of 532nm and 75mJ, a camera with a resolution of 2360 X 1776 pixels and a frequency of 16 frames per second. The agitation tank used is made of acrylic with a diameter of 25cm (T), with four baffles 3mm thick and 2.5cm wide, mounted equidistant on the internal walls. The impeller was placed concentrically at a height from the bottom of the tank equal to C= 1/3T. The working fluid is water and about 12 liters are used to fill the tank to a height of 25cm (H). In addition, the commercial software ANSYS® Fluent® was used to implement the Large Eddy Simulation, in order to investigate the affinity of these results with those obtained experimentally. The implementation of the grooves on the surfaces of the blades led to a reduction in the power number and the pumping number. Furthermore, the distributions of the dissipation rate and of turbulent kinetic energy were modified.