Y.-F. Fu’s scientific contributions

Control of the tip leakage is investigated in a turbine cascade with honeycomb tip using injection numerically. Tip leakage flow rate and energy loss coefficient are selected to evaluate the aerodynamic performance. Results show that the tip leakage flow rate and the energy loss downstream both can be further reduced after using the injection. Compared with the flat tip, tip leakage flow rate drops by up to 17.5 percent, and energy loss downstream is reduced by about 4.8 percent. From three-dimensional flow analysis, the leakage fluid enters the honeycomb cavities layer by layer along the span-wise direction and is involved into the internal vortices. The injection increases the span-wise scales of the internal vortices indirectly, raises the upper leakage fluid and reduces the leakage flow area.

In this paper, the influence of a new spherical-bottom honeycomb tip structure on the leakage flow of turbine cascade is numerically studied. The influence of the depth of the bottom on the leakage flow is also investigated. The results show that vortices change the structure of the flow field in the honeycomb cavity, and the composite structure with the spherical-bottom honeycomb reinforces this type of vortex, which has a better suppression effect on the leakage flow. Compared with the conventional at tip, the leakage flow of the cascades with honeycomb tip and spherical-bottomed honeycomb tip decreased by 11.18% and 15.13%, and the exit losses decreased by 8.17% and 10.42% respectively. For the spherical-bottom honeycomb tip cascade, both the amount of leakage flow and the loss change parabolically with the geometric depth of the spherical bottom. At the ball depth of 1/6 of the ball diameter, minimum leakage flow and exit loss can be got.