Abstract
The results are given of the film cooling numerical simulation of three different schemes including single-array of the traditional round inclined holes, as well as inclined holes arranged in the cylindrical or triangular dimples (craters). The results of simulation showed that at the medium and high values of the blowing ratio ( m > 1.0) the scheme with coolant supply into triangular craters improves the adiabatic film cooling efficiency by 1.5…2.7 times compared to the traditional array of inclined holes, or by 1.3…1.8 times compared to the scheme with coolant supply into cylindrical craters. The greater film cooling efficiency with the coolant supply into triangular craters is explained by decrease in the intensity of secondary vortex structures (“kidney” vortex). This is due to the partial destruction and transformation of the coolant jets structure interacting with front wall of the crater. Simultaneously, the film cooling uniformity is increased in the span-wise direction.
Highlights
The film cooling is the most efficient technique for protection of turbine blades in advanced high-performance gas turbines
The traditional film cooling technique (Fig.1 а) has a number of disadvantages; the primary of them is the low film cooling efficiency at the high value of blowing ratio (m > 1.0). It is caused by the appearance of specific vortex structures in the flow contributing to the detachment of coolant jets from the cooled surface and the hot gas flowing under the coolant jets
The results of the numerical studies (Fig.2) have shown that at the medium and high value of the blowing ratio (m > 1.0) the scheme with coolant supply into triangular craters increases the average adiabatic film cooling efficiency by 1.5...2.7 times compared to the traditional scheme of a single array of inclined round holes, and by 1.3...1.8 times compared to the scheme with coolant supply into cylindrical craters
Summary
The film cooling is the most efficient technique for protection of turbine blades in advanced high-performance gas turbines. In the Institute of Engineering Thermophysics of the National Academy of Sciences of Ukraine the new film cooling configuration was proposed with a coolant supply through the single array of inclined round holes [6] arranged in the triangular-shaped craters (Fig. c). This leads to the transformation of separate coolant jets into the semi-bounded twodimensional jet, reducing the coolant discreteness when supplying onto protected surface
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