A Review of Hole Geometry and Coolant Density Effect on Film Cooling

Ekkad, Srinath V.; Han, Je-Chin

doi:10.5098/hmt.6.8

Cited by 13 publications

(3 citation statements)

References 43 publications

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“…There are many studies on the shape of film-cooling holes. The effect of the hole shape on the cooling performance was reviewed by Ekkad and Han [ 3 ] and Zhang et al [ 4 ]. Basic hole shapes include slots and cylindrical holes.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Double-Expansion Film-Cooling Hole Using CFD

Zhang

Chen

et al. 2023

Entropy

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Film cooling is a major cooling technique used in modern gas turbines and air engines. The geometry of film-cooling holes is the fundamental aspect affecting the cooling performance. In this paper, a new cooling configuration called the double-expansion film-cooling hole has been put forward, which yields better performance than the widely used shaped holes and is easy to manufacture. The double-expansion holes at inclination angles of α=30∘, 45∘, and 60∘ are optimized using the genetic algorithm and the Kriging surrogate model, which is trained by CFD data randomly sampled using the Latin hypercube method. The numerically optimized double-expansion holes at different inclination angles were experimentally evaluated and compared with the optimized single-expansion laid-back fan-shaped holes, and the optimized double-expansion hole at α=30∘ was manually modified based on experiment results. Compared with the optimal single-expansion holes, the area-averaged cooling effectiveness of the double-expansion holes was increased by 34.5% at α=30∘, by 27.8% at α=45∘, and basically the same at α=60∘, showing the benefit of the double-expansion concept. The loss mechanism of film cooling was also analyzed in the perspective of the entropy generation rate, showing the optimal double-expansion holes have 21% less loss compared to a baseline narrow single-expansion hole. It was also found that CFD sometimes predicts a different trend from the experiment in optimization, and the experimental validation is necessary.

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Section: Introductionmentioning

confidence: 99%

Optimization of the Double-Expansion Film-Cooling Hole Using CFD

Zhang

Chen

et al. 2023

Entropy

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“…Great efforts have been put into the research works of film cooling in the past few decades (Han and Ekkad, 2001). The research works about film cooling have accumulated a large amount of literature, such as the shape optimization and location arrangement of the cooling holes (Ekkad and Han, 2013). For the geometrical effects of film cooling holes, research works are mainly focused on improving the coolant coverage on the solid surface, such as compound angle film cooling holes and cooling holes with a trench (Sundaram and Thole, 2008;Sundaram and Thole, 2009).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigations of endwall film cooling design of a turbine vane using four-holes pattern

Liu

et al. 2021

HFF

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Purpose Endwall film cooling protects vane endwall by coolant coverage, especially at the leading edge (LE) region and vane-pressure side (PS) junction region. Strong flow impingement and complex vortexaa structures on the vane endwall cause difficulties for coolant flows to cover properly. This work aims at a full-scale arrangement of film cooling holes on the endwall which improves coolant efficiency in the LE region and vane-PS junction region. Design/methodology/approach The endwall film holes are grouped in four-holes constructal patterns. Three ways of arranging the groups are studied: based on the pressure field, the streamlines or the heat transfer field. The computational analysis is done with the k-ω SST model after validating the turbulence model properly. Findings By clustering the film cooling holes in four-holes patterns, the ejection of the coolant flow is stronger. The four-holes constructal patterns also improve the local coolant coverage in the “tough” regions, such as the junction region of the PS and the endwall. The arrangement based on streamlines distribution can effectively improve the coolant coverage and the arrangement based on the heat transfer distribution (HTD) has benefits by reducing high-temperature regions on the endwall. Originality/value A full-scale endwall film cooling design is presented considering interactions of different film cooling holes. A comprehensive model validation and mesh independence study are provided. The cooling holes pattern on the endwall is designed as four-holes constructal patterns combined with several arrangement choices, i.e. by pressure, by heat transfer and by streamline distributions.

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“…The results of a spectral analysis indicated a high correlation between the shedding period of the CRVP and the film-cooling effectiveness (Chen et al, 2020). Thus, further investigations of the vortex effect in the jet in cross flow process are in great demand to help to predict the cooling effectiveness distributions (Ekkad & Han, 2013). In previous studies, many vortex visualization methods (Chong et al, 1990;Hunt et al, 1988;Jeong & Hussain, 1995;Zhou et al, 1999) are proposed based on the velocity gradient tensor.…”

Section: Introductionmentioning

confidence: 99%

Vortex identification and evolution of a jet in cross flow based on Rortex

Zhan

Chen

et al. 2020

Engineering Applications of Computational Fluid Mechanics

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Jet in cross flow is an important issue in engineering practice, for example, it is used to improve turbine efficiency in film cooling. In this study, the large eddy simulation and the spectrum analysis are employed to analyze the vortices in a jet in cross flow. The results show that the Rortex method more accurately identifies the vortex structures than other methods. In the analysis of the evolution of the spatial vortex structures, it is affirmed that the spectrum analysis using the Rortex value can effectively identify the characteristic vortex structures in a jet in cross flow.

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A Review of Hole Geometry and Coolant Density Effect on Film Cooling

Cited by 13 publications

References 43 publications

Optimization of the Double-Expansion Film-Cooling Hole Using CFD

Optimization of the Double-Expansion Film-Cooling Hole Using CFD

Numerical investigations of endwall film cooling design of a turbine vane using four-holes pattern

Vortex identification and evolution of a jet in cross flow based on Rortex

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