Trailing-Edge Cooling for Gas Turbines

Cunha, F. J.; Chyu, Minking K.

doi:10.2514/1.20898

Cited by 61 publications

(18 citation statements)

References 18 publications

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“…It was recognised that the increase of the t/H ratio from 0.5 to 1.0 would decrease the overall film-cooling effectiveness by about 10%. Similar findings were noted and confirmed by Cuhna et al [15] and further discussed by Goldstein [16]. Sivasegaram et al [17] and Burns et al [18] reported that the decrease of the t/H ratio is a key factor to increase the film-cooling effectiveness.…”

Section: Introductionsupporting

confidence: 80%

“…In this study, it was found that the difference between the highest and the lowest heat transfer levels of all pin-fin rows is approximately 45.45%. In comparison, Cunha et al [15] noted up to 38.46% in their experiment [44], all of whom investigated the heat transfer in the parallel duct with seven-rows of pin-fin arrays. These researches confirmed that the heat transfer increases through the first three rows and then reduces for the remaining rows.…”

Section: Heat Transfer Coefficient At the Pin-fin Surfacesmentioning

confidence: 99%

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DES study of blade trailing edge cutback cooling performance with various lip thicknesses

Effendy

Yao

et al. 2016

Applied Thermal Engineering

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Highlights Detached-eddy simulation of the mixing process between mainstream flow and coolant;  Effects of various t/H ratios on blade trailing-edge cutback cooling performance;  Vortex shedding behind the lip plays an important role in near wall cooling efficiency;  Discharge coefficient and adiabatic film-cooling effectiveness agree with experiment;  Thermal mixing has been greatly intensified with the increase of the t/H ratio. ABSTRACTThree-dimensional detached-eddy simulation (DES) study has been carried out to evaluate the cooling performance of a trailing-edge cutback turbine blade with various lip thickness to slot height ratios (t/H). By adopting the shear-stress transport (SST) k-ω turbulence model, the numerical investigations were performed at two successive steps: first, to validate simulation results from an existing cutback turbine blade model with staggered circular pin-fins arrays inside the cooling passage against experimental measurements and other available numerical predictions; second, to understand the effects of the lip thickness to the slot height ratio on the blade trailing-edge cooling performance. It was found from the model validations that at two moderate blowing ratios of 0.5 and 1.1, DES predicted film cooling effectiveness are in very good agreement with experimental data. Further comparisons of four various t/H ratios (t/H = 0.25, 0.5, 1.0, 1.5) have revealed that the thermal mixing process between the 'cold' coolant gas and the 'hot' mainstream flow in the near wake region of the exit slot has been greatly intensified with the increase of the t/H ratio. As a result, it causes a rapid decay of the adiabatic film cooling effectiveness downstream of the blade trailing-edge. The observed vortex shedding and its characteristics in the near wake region are found to play an important role in determining the dynamic process of the 'cold' and the 'warm' airflow mixing, which in turn have significant influences on the prediction accuracy of the near-wall heat transfer performance. As the four t/H ratio increases from 0.25 to 1.5, DES predicts the decrease of main shedding frequencies as f s = 3.69, 3.2, 2.21, and 1.49 kHz, corresponding to Strouhal numbers S t = 0.15, 0.20, 0.23, and 0.22, respectively. These results are in good agreement with available experimental measurements.

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Section: Introductionsupporting

confidence: 80%

Section: Heat Transfer Coefficient At the Pin-fin Surfacesmentioning

confidence: 99%

DES study of blade trailing edge cutback cooling performance with various lip thicknesses

Effendy

Yao

et al. 2016

Applied Thermal Engineering

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“…The coolant feeding channel was stiffened by a pin fin array followed by ribs extending up to the trailing edge. Cunha and Chyu (2006) measured g and the heat transfer coefficient distributions downstream of a cutback model with internal shaped pedestals and external lands. From the results of the analysis of Martini et al (2005a), Krueckels et al (2009) identified the most important design parameters for a pressure side bleed trailing edge cooling, taking into account for the internal feeding channel geometry.…”

Section: Cutback Trailing Edge Studiesmentioning

confidence: 99%

Experimental investigation of the effects of blowing conditions and Mach number on the unsteady behavior of coolant ejection through a trailing edge cutback

Barigozzi¹,

Armellini²,

Mucignat³

et al. 2012

International Journal of Heat and Fluid Flow

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“…In most practical applications, coolant flow is ejected from the blade trailing edge directly to the base region where the pressure level is an indicator of profile losses, while the shock system generates losses mainly through the shock/boundary layer interaction on the neighbouring airfoils [11].The effect of cooling applications on the loss mechanisms and the improvements obtained by employing various configurations are well documented by many experimental and numerical investigations [12][13][14][15]. Moreover, different configurations of coolant ejection geometries were tested in terms of thermal and aerodynamic efficiencies [16].…”

Section: Introductionmentioning

confidence: 99%

Mitigation of Turbine Vane Shock Waves Through Trailing Edge Cooling

Cakir

Saracoglu

2018

MATEC Web Conf.

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Abstract. The immense market demand on the high efficiency and lightweight aero-engines results in designs with compact high-pressure turbine stages experiencing supersonic flow field. In supersonic turbines, shocks appear at the vane trailing edges. The interaction of these shock with the neighbouring airfoils and blades on the adjacent rotor row and consequently create considerable amount of losses on the aerodynamic performance of the turbine. Moreover, periodic excitation created by the interaction of the shock waves and the motion of the turbine rotor causes fatigue problems and reduces the lifetime of the engine. Current study aims to alter the vane shock waves through blowing at the trailing edge. In order to characterize the effect of active blowing on the trailing edge flow field, a series of URANS simulations were conducted on OpenFOAM solver platform. Various blowing schemes were simulated over a simplified trailing edge geometry exposed in supersonic flow. The computations were compared in terms of shock intensity, oscillation frequency and exerted pressure forcing over the downstream components. The results showed that unsteady trailing edge blowing were able to modify the fluctuations observed on the shocks by altering the shock intensity, angle and frequency of oscillations. The classification of the wake unsteadiness, i.e. vortex shedding, in terms of trailing edge characteristics were also accomplished through frequency domain analysis of simulations.

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Trailing-Edge Cooling for Gas Turbines

Cited by 61 publications

References 18 publications

DES study of blade trailing edge cutback cooling performance with various lip thicknesses

DES study of blade trailing edge cutback cooling performance with various lip thicknesses

Experimental investigation of the effects of blowing conditions and Mach number on the unsteady behavior of coolant ejection through a trailing edge cutback

Mitigation of Turbine Vane Shock Waves Through Trailing Edge Cooling

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