Performance of Gas Turbine Film Cooling with Backward Injection

Li, X. C.; Subbuswamy, Ganesh; Zhou, Jiang

doi:10.4236/epe.2013.54b025

Cited by 13 publications

(5 citation statements)

References 14 publications

(14 reference statements)

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“…A similar finding for similar mass flux ratio cases is reported by previous researchers as well, such as Kohli and Bogard [8]. Li et al [9] obtained backward jets to work better than forward jets with mass flux ratio (MR) 2.0. The present MR is 0.49, and forward jets are found to be more effective.…”

Section: Pipe Inclination Anglesupporting

confidence: 88%

“…The cooling jet diffuses significantly at higher injection angles. Despite the known advantage of low inclination angles, the backward injection (i.e., inclination angle more than 90°) is found to improve the film cooling performance on flat surface at both laboratory and gas turbine operating conditions with blowing ratio more than 0.75 [9].…”

Section: Review Of Past Researchmentioning

confidence: 88%

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The Effects of Coolant Pipe Geometry and Flow Conditions on Turbine Blade Film Cooling

Akbar¹

2017

Journal of Thermal Engineering

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The performance of gas turbine engines can be improved by increasing the inlet gas temperature. Turbine blades can be damaged by high gas temperature, unless additional cooling mechanisms are incorporated to maintain the blades below an acceptable temperature limit. Film cooling techniques are often used to cool the blades to avoid damages. The performance of film cooling depends on several parameters, however. In this paper past research on film cooling is reviewed and areas in need of further investigation are identified. Computational fluid dynamics (CFD) simulations are then conducted on the widely-used single-hole film cooling arrangements in which coolant jets are injected into air flows inside a straight channel before issuing onto the blades. Cooling pipe-blade configurations and flow conditions are varied and the resulting flow hydrodynamics are examined. Counter rotating vortex pairs (CRVPs) formed in the flow strongly influence the film cooling performance. Small coolant inclination angles, exit holes enlargement in span wise direction, higher injected fluid density, and higher injectedambient fluid velocity ratios are all found to maintain the CRVPs away from each other and close to wall -both of which promote cooling. Pipe curvature can be used for enhancing cooling by exploiting the centrifugal force effect.

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Section: Pipe Inclination Anglesupporting

confidence: 88%

Section: Review Of Past Researchmentioning

confidence: 88%

The Effects of Coolant Pipe Geometry and Flow Conditions on Turbine Blade Film Cooling

Akbar¹

2017

Journal of Thermal Engineering

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“…Over the past decades, film cooling with forward coolant injection was the main focus. Recently, a research group from Lamar University inspired the researches on film cooling with backward coolant injection [7][8][9][10]. These studies provided a clear understanding on the backward injection film cooling.…”

Section: Introductionmentioning

confidence: 99%

Numerical Evaluation on Effects of Upstream Sand-Dune-Shaped Ramp and Backward Coolant Injection on Heat Transfer

Deng¹,

Yu²,

Huang³

et al. 2023

J. Phys.: Conf. Ser.

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Numerical simulations are performed for the forward and backward injection film cooling with the presence of upstream ramp under three typical blowing ratios of 0.5, 1.0 and 1.5. Totally nine film cooling configurations are taken into considerations in the current study, where two ramps (straight-wedge-shaped ramp (SWR) and sand-dune-shaped ramp (SDR)), two coolant injection modes (forward injection (FW) and backward injection (BW)), and two film-hole shapes (cylindrical hole (CH) and fan-shaped hole (FH)) are involved. From the current study, the effects of coolant injection scheme and upstream ramp on the film cooling performance are evaluated in the viewing of the heat transfer. Based on the numerical results, it is demonstrated that a wide high net heat flux reduction (NHFR) zone is created in the forward injection cases at M(the blowing ratio)=0.5, but it is shrunk or disappeared rapidly at M=1.5, except the FH-FW-SDR case. While for the backward injection case, two high heat flux reduction zones are generated around the hole exit where the separate bubbles locate, and it remains even at M=1.5. Among the current cases, the FH-FW-SDR is demonstrated to be the best one for achieving the highest NHFR under the all three blowing ratios. With regard to the coolant injection scheme, its influence on heat transfer coefficient is more complicated, tightly associated with the blowing ratio, film-hole shape and the upstream ramp.

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“…In actuality, the coolant injection orientation is also a paramount factor that affects the mutual interaction between coolant jets and primary flow, and subsequently the film cooling performance. The backward injection, an opposite scheme to forward injection, was illustrated by Li et al [28] and Subbuswamy et al [29,30] to own a unique interaction feature of jet-in-crossflow, leading to a better jet spreading in the lateral direction but a worse jet spreading along the streamwise direction on the whole. Because backward coolant injection could provide a uniform film cooling in the lateral direction relative to the forward coolant injection, it was suggested to be a possible scheme for weakening the thermal gradients.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on Backward-Injection Film Cooling with Upstream Ramps

et al. 2022

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The present study investigates the effects of upstream ramps on a backward-injection film cooling over a flat surface. Two ramp structures, referred to as a straight-wedge-shaped ramp (SWR) and sand-dune-shaped ramp (SDR), are considered under a series of blowing ratios ranging from M = 0.5 to M = 1.5. Regarding the backward injection, the key mechanism of upstream ramps on film cooling enhancement is suggested to be the enlargement of the horizontal scale of the separate wake vortices and the reduction of their normal dimension. When compared to the SDR, the SWR modifies the backward coolant injection well, such that a larger volume of coolant is suctioned and concentrated in the near-field region at the film-hole trailing edge. As a consequence, the SWR demonstrates a more pronounced enhancement in film cooling than the SDR in the backward-injection process, which is the opposite of the result for the forward-injection scheme. For the SWR, the backward injection provides a better film cooling effectiveness than the forward injection, regardless of blowing ratios. However, for the SDR, the backward injection could show a superior effect to the forward injection on film cooling enhancement, when the blowing ratio is beyond a critical blowing ratio. In the present SDR situation, the critical blowing ratio is identified to be M = 1.0.

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Performance of Gas Turbine Film Cooling with Backward Injection

Cited by 13 publications

References 14 publications

The Effects of Coolant Pipe Geometry and Flow Conditions on Turbine Blade Film Cooling

The Effects of Coolant Pipe Geometry and Flow Conditions on Turbine Blade Film Cooling

Numerical Evaluation on Effects of Upstream Sand-Dune-Shaped Ramp and Backward Coolant Injection on Heat Transfer

Numerical Investigation on Backward-Injection Film Cooling with Upstream Ramps

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