Effects of Turbulence Promoters of Gas Turbine Blades on Film Cooling Performance

Abstract

The effects of orientation of turbulence promoting ribs in the internal cooling air passage on the film cooling performance of outer surface of gas turbine blades have been studied experimentally. Both the adiabatic film cooling effectiveness and the heat transfer coefficient downstream of the film-cooling hole of a flat plate were measured for two different orientations of the turbulence promoting ribs. It is found that the adiabatic film cooling effectiveness and heat transfer coefficient on the external surface are considerably affected by the inversion of the rib orientation in the internal passage. The film cooling performance is evaluated in terms of the net heat flux reduction and the net surface temperature reduction, both of which are calculated from the measurement of adiabatic film cooling effectiveness and heat transfer coefficient. The evaluation of these quantities has clarified the effects of the internal cooling structure on the film cooling performance.

Numerical Simulation of Heat Transfer Coefficient and Film-Cooling Performance Influenced by the Orientation of Internal Turbulence Promoting Ribs

“…More recently, the effect of turbulence promoting ribs for internal convective cooling has been considered by Kissel et al (5) . The authors of the present paper have experimentally shown that the rib orientation has a marked effect on the film-cooling performance evaluated in terms of the net heat flux reduction (hereafter, γ) and the net surface temperature reduction (hereafter, χ) (6) . In their subsequent study (7) , the mechanisms underlying the modifications of the adiabatic film cooling effectiveness (hereafter, η) due to rib orientation have been shown from the results obtained from computational fluid dynamics (CFD) analysis.…”

“…1. This configuration is the same as the film-cooling configuration examined in our previous experimental (6) and numerical (7) studies. The domain considered here includes heat transfer surfaces, an internal passage and a film-cooling hole, representing an enlarged simplified model of the real turbine blade.…”

“…8, No. 3, 2013 considered rib orientations and rib dimensions are also the same as the previous studies (6) (7) as shown in Fig. 2.…”

“…Note that experimental h 0 values (6) are utilized for this evaluation. In order to study BR dependency of HTC characteristics, the present simulations are conducted for low and high BRs, as shown in Table 1.…”

“…The first objective is to obtain detailed information of HTC from CFD analyses based on the detached eddy simulation (DES) and to indicate through the comparison with experiments (6) that the influence of the rib orientation on the HTC can be reasonably simulated. The present simulations are conducted for the same flow conditions as in the previous ones (7) under different thermal boundary conditions that are relevant for the evaluation of HTC.…”