In this paper, we conduct an experimental and computational study about trailing edge cooling of a gas turbine blade with perforated blockages with inclined holes. The internal cooling passage is modeled as a wide square channel with 2 parallel blockages. There are 7 inclined holes in each blockages. The holes have an inclined angle of 30°, and the adjacent impingement holes have opposite orientations with each other, so that both up and down wall could be cooled. There are 2 patterns of configurations. The basic one has round shape holes with a diameter of 20 mm (D). The second one has oval shape hole which is made up of two parallel lines with the length of 20mm and two opposite semicircle with a diameter of 20 mm. This design is aimed at enlarging the opening area of the blockages. The height of the cooling channel is 2D and the width of the cooling channels is 20D. The space between each hole is 3D. The distance between two blockages is 5D. The main purpose of this paper is to study the effect of holes shape on heat transfer performance, both heat transfer coefficient and friction factor are evaluated. Heat transfer coefficient is measured using transient liquid crystal method. And pressure dissipation is measured by three holes probe. The Reynolds Number ranges from 10000 to 20000. The result shows that round shape structure has the highest average heat transfer coefficient as well as the highest friction factor. And oval shape structure has the lowest average heat transfer as well as the lowest friction factor. The main reason of this phenomenon is opening area ratio. Oval shape structure has bigger opening area and lower flow resistance. Round shape structure has a lower opening area ratio which result in stronger impingement flow. To investigate the flow characteristic of these structures in detail, numerical simulations was conducted. The mesh for each structure contains approximately 4 million cells. The result shows a clear picture of flow inside the inclined holes.
展开▼
