Study On The Characteristics Of Magnesia Particles Fouling Of Punching Rectangular Wing Vortex Generator

The existence of fouling has universality and harmfulness. The vortex generator can induce vortex to generate secondary flow, promoting the mixing of the main area and the wall boundary layer. In the heat transfer equipment, the vortex generator is used as a passive heat transfer enhancement device to enhance heat transfer. Further more, it also can inhibit the formation of fouling. In the study, rectangular wing vortex generator has been widely concerned because of its easy manufacture processing. Under the condition of the same height, width and attack angle, the rectangular wing vortex generator has the better ability of anti fouling, but the loss of flow resistance is the biggest. In order to improve the comprehensive performance of rectangular wing vortex generator, punching rectangular wing vortex generator is used as the research object with the Magnesium Oxide nano-particles being as the working fluid. The characteristics of fouling and flow in rectangle channel are researched by the on-line fouling resistance monitoring method.First of all, the experiments of plate, non punching rectangular winglet vortex generators and punching rectangular wing vortex generator with aperture r=1mm are carried out. The experiment has two ascepts: the fouling characteristics and the flow resistance characteristics. The results show that: the jet flow can be formed when the working fluid flows through the rectangular wing vortex generator, which would increases the scour of the area behind the wing surface. So in the same working condition, compared with non punching vortex generator, punching rectangular wing vortex generator has better inhibition scale and smaller loss of the flow resistance. On the basis of this, the fouling resistance characteristics of the punching rectangular wing vortex generator are further analyzed in the case of different aperture size, number of holes and the position of the holes. The results show that with the increase of the diameter of punching vortex generator, asymptotic value of fouling resistance decrease, but the amplitude of decrease is reduced. The more number of punching holes, the smaller asymptotic value of fouling resistance, but they are not in proportion to the change. When the punching holes locate outside position of vortex generator, they can gain a better ability in restrain fouling.Secondly, the effects of different conditions on the fouling resistance characteristics of punching rectangular wing vortex generator are tested. These experiments are carried out on three aspects, including the temperature of water bath, the concentration of working medium and the flow velocity of working fluid. The experimental results show that the fouling resistance asymptotic value of Magnesium Oxide nano-particles would increases with the rise of water bath temperature, and the rate of fouling is also increases. With the increases of the concentration of working medium increases, the asymptotic value of fouling resistance increases. At the same time, the fouling rate increases too. The asymptotic value of fouling resistance and fouling rate would decrease with the increase of working fluid velocity.