COMPUTATIONAL INVESTIGATION OF FILM COOLING AIRS EJECTED FROM ROW TRENCH AND CYLINDRICAL HOLES

Abstract

Gas turbine industries are trying to expand the performance of the gas turbine engine. Using the well-known Brayton cycle, the combustion outlet temperature must be increased to achieve higher efficiency. However, increased turbine inlet temperature creates a harsh environment for downstream combustion components. This requires the design of an efficient cooling technique in this field. In a traditional cooling system, the coolant does not attach well to the surface at higher blow ratios. This requires changing the structure of the cooling holes. A useful way would be to trench the cooling holes in the surface of the end wall of the combustion chamber and align the trenched holes in a row. The major effects of cylindrical and row cooling holes with different alignment angles of 0, ±60 and 90 degrees at BR=1.25 and BR=3.18 on the film cooling effectiveness near the combustion end wall surface are an important issue that needs to be studied in detail. In the present study, the researchers used the FLUENT 6.2.26 package to simulate a 3D model of a Pratt and Whitney gas turbine engine. In this research, RANS model was used to analyze the flow behavior in internal cooling passages. In the combustion simulator, the dilution jets and the cooling stream moved in the flow direction and were also aligned in the transverse direction. Compared to the base case of cooling holes, the use of row holes near the end wall surface increased the film cooling effectiveness from 75% to 100% for different trench cases.