In this paper, the effect of a novel honeycomb tip on suppressing tip leakage flow has been experimentally and numerically studied. The research focuses on the mechanisms of honeycomb tip on suppressing tip leakage flow and affecting the secondary flow, as well as the influences of different clearance heights on leakage flow characteristics. In addition, two kinds of local honeycomb tip structures are proposed to explore the positive effect on suppressing leakage flow.
Honeycomb tip rolls up a number of small vortices and forms radial jets in honeycomb cavities, increasing the flow resistance in the clearance and reducing the velocity of leakage flow. As a result, honeycomb tip not only reduces the leakage flow effectively, but also has positive effect on reducing the losses by reducing the strength of leakage vortex. Compare to the flat tip cascade, the relative leakage flow reduces from 3.05% to 2.73%, and the loss at exit section is decreased by 10.63%. With the increase of the gap height, the tip leakage flow and loss have variations of direct proportion with it, but the growth rates in the honeycomb tip cascade is smaller. Consider the abradable property of the honeycomb seal, a smaller gap height is allowed with honeycomb tip, which means honeycomb tip can perform better. Two various local honeycomb tip structures has also been discussed. It shows that local raised honeycomb tip has better suppressing leakage flow effect than honeycomb tip, while local concave honeycomb tip has no more effect.