Continuously arranged converging slot-holes are set on a C3X stator
which contains a U-bend channel at the front of the airfoil and a radial channel near the trailing edge inside the airfoil by solidworks. Cylindrical hole model and fan-shaped hole model are also constructed in the same way. Each model has four rows of film cooling holes. In the slot-hole case
there are 23 holes with a pitch of 20 millimeters in one film cooling hole row. In the cylindrical and fan-shaped hole case
there are 19 holes with a pitch of 24 millimeters in one film cooling hole row. Cooling air is supplied to film cooling holes through the U-bend channel and the radial channel. These three models are meshed by structured grids with ANSYS-ICEM. ANSYS-CFX and SST turbulence model is used to calculate the turbulent flow. The adiabatic cooling performance of converging slot-holes is compared with that of cylindrical holes and fan-shaped holes in different blowing ratio
the heat transfer enhancement mechanism of converging slot-holes is analyzed
and the adiabatic cooling effectiveness and the overall cooling effectiveness are compared. The Result shows that converging slot-hole has the highest adiabatic cooling effectiveness and the advantages become more obvious at the larger blow ratio. A kind of vortex which looks like anti-kidney vortex is found downstream of continuous arranged converging slot-holes. The intensity of the vortex is not very high but maintains in a long distance and increases the coverage of the coolant film on the surface of the stator. The internal cooling has a non-ignorable influence on the numerical result. As a consequence
conjugate cooling has less resistance to jet lift-off. The overall effectiveness is lower than the adiabatic effectiveness at the exit of slot-holes. In the practical application of the continuous arranged converging slot-hole rows
large blowing ratio and small injection angle are beneficial to promote the film cooling efficiency.
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references
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