DefinePK

Abstract

In order to provide thermal protection for the external surface of the gas turbine blades, film cooling technique has been applied. With the aim to reduce the lift-off effect cause by the counter rotating vortex pair (CRVP) formed in the cylindrical cooling hole configuration, coupling film cooling designs have been introduced. Double Cylindrical Hole (DCH) which is one of the coupling holes is the main subject for the present study with the implementation of two geometrical parameters; length between the holes in x-direction, LoD and upstream ramp. Five double cylindrical hole arrangements have been developed with these two parameters and DCH 2D35 is considered as the baseline which will be discuss more later on. Meanwhile for the flow parameter, the main parameter considered is blowing ratio, M. ANSYS CFX ver. 15 has been used in the present work and all the analyses have been carried out using Reynolds Average Navier Stokes analysis with the implementation of k-? turbulence model. In general, the results show that the increase in LoD hindering the film cooling effectiveness at the distinct hole region, but decays slower in the downstream compared to the baseline design. Meanwhile, the results of upstream ramp variations demonstrate that the upstream ramp shows significant improvement of film cooling effectiveness at near exit hole region, but as the film cooling moves further downstream, it decays rapidly in comparison with the baseline. As for the blowing ratio effect, the film cooling have been observe to decay as the blowing ratio increases similar to the general ideas of conventional cooling hole.