A Numerical Study of Heat and Mass Transfer in a Narrowing Channel with Pin Fin-Dimple Arrays

Gas turbine development is a high priority part of the Russian power industry modernization. The power production efficiency mostly may be improved by increase of the working fluid parameters. The increase of turbine inlet temperature and pressure requires a larger number of cooled stages and the cooling channels Reynolds numbers grow above 80000. This encourages the development of new technology to intensify the channels heat transfer at high Re values. The computer studies described are concerned to heat transfer improvement in the trailing edge of convective cooled blades compared with the traditional chequerwise located cylindrical pins in narrowing channels. In the first studied version, the channel heat transfer is intensified with a cluster of chequerwise located pins of 2 mm in diameter. Longitude and transversal pitches of pins are equal to 5 mm. In the second version, the pins are installed in dimples of 4 mm in diameter and 0.5 mm depths. The results of numerical modeling in Ansys CFX show that application of the developed pin fin-dimple flow turbulizers in the trailing edge area improves the heat transfer for 33-41% at the Reynolds numbers from 20000 to 85000 compared to the chequerwise pins array.