Experimental and numerical investigation of narrow impingement cooling channels

Fechter, Stefan; Terzis, Alexandros; Ott, Peter; Wolfersdorf, Jens von

doi:10.1016/j.ijheatmasstransfer.2013.09.003

Cited by 50 publications

(14 citation statements)

References 25 publications

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“…The wall-jet flow in the channel interferes with the sidewalls causing a post-impingement flow to the impingement plate. The uplift moving of the flow causes therefore higher local heat transfer coefficients closer to the sidewalls of the channels, as shown in Figure 5(c), which is in agreement with Caggese et al 25 and Fechter et al 26 The surface contours show that the h/h max are increased at downstream channel positions, which means that crossflow enhances impingement plate heat transfer. However, the achievable heat transfer in the vicinity of the first jets, N j ¼ 1 and 2, is very low indicating small interaction with the post-impingement flow.…”

Section: Local and Spanwise Averaged Heat Transfer Distributionssupporting

confidence: 89%

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Heat transfer characteristics of high crossflow impingement channels: Effect of number of holes

Llucià

Terzis

Ott

2015

Proceedings of the Institution of Mechanical Engineers, Part A:

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In modern turbine airfoils, narrow impingement cooling channels can be formed in a double-wall configuration. In these wall-integrated cooling cavities, the generated crossflow is one of the most important design factors, and hence, the number of impingement holes included in a channel. This study examines experimentally the influence of the number of impingement holes on the heat transfer characteristics of narrow impingement channels. The channels consist of two rows of jets where the number of holes in the axial direction is varied from 5 to 10, maintaining the same jet plate open area. Local heat transfer coefficient distributions are obtained for all channel interior walls using the transient liquid crystal technique and over a range of Reynolds numbers (20,300–41,500). The results show an important heat transfer degradation at higher open areas and a small influence of the number of holes at upstream channel positions.

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Section: Local and Spanwise Averaged Heat Transfer Distributionssupporting

confidence: 89%

“…25 and Fechter et al. 26 The surface contours show that the h / h max are increased at downstream channel positions, which means that crossflow enhances impingement plate heat transfer. However, the achievable heat transfer in the vicinity of the first jets, N j = 1 and 2, is very low indicating small interaction with the post-impingement flow.…”

Section: Resultsmentioning

confidence: 95%

Heat transfer characteristics of high crossflow impingement channels: Effect of number of holes

Llucià

Terzis

Ott

2015

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Moffat [19,20] gave a description of errors' sources by using uncertainty in the planning of experiments. Besides that, Root-Sum-Square (RSS) method was used to predict the uncertainty by Caggese et al [21] and Fechter et al [22]. Table 2 shows errors and uncertainty levels of measured parameters in the calculation of effectiveness of porous plate, efficiency of the system and the Reynolds number.…”

Section: Data Reductionmentioning

confidence: 99%

A heat transfer analysis from a porous plate with transpiration cooling

Kılıç

2019

THERM SCI

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Present study is focused on improving heat transfer from a porous plate by cooling of air with transpiration cooling. Effects of Reynolds number of the air channel flow and particle diameter on cooling effectiveness of porous plate and efficiency of system were investigated experimentally. It was observed that increasing Reynolds number of 15.2% causes a decrease of 6.9% on cooling efficiency of the system and a decrease of 8.6% on cooling effectiveness of porous plate. Decreasing particle diameter causes a significant decrease on surface temperature and an increase on cooling effectiveness of porous plate. Difference of cooling effectiveness of porous plate from dp = 40-200 ?m is 12%. Verification of this study was also shown by comparing experimental results of this study with literature.

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“…The relationship between flow topology and heat transfer has to be fully understood before optimizing the geometry of a multi-jet narrow impingement cavity. Although there are a few CFDoriented works for these kind of geometries (Fechter et al, 2013;Hossain et al, 2016Hossain et al, , 2018, they are mainly focused on the capabilities of the CFD models to accurately predict the wall imprint of transfer. The only purely experimental work that focused on the flow physics and its relation to convective transport was presented by Terzis (2016), who investigated mutual-jet interactions for a lowand a high-crossflow narrow impingement channel.…”

Section: Influence Of Flow Structures On Heat Transfermentioning

confidence: 99%

Narrow impingement channels: recent advancements and future directions

Gaffuri¹,

Terzis²,

Ott³

2019

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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This paper summarizes the state-of-the-art related to the heat transfer characteristics of narrow impingement cooling channels, which can nowadays be integrated within the external wall of turbine airfoils. Particular emphasis is given to the experimental outcomes of the research activities performed at the Group of Thermal Turbomachinery (GTT) of EPFL over the last 10 years. The influence of various geometrical factors on the heat transfer distributions is demonstrated, aiming to provide a summarized physical knowledge for the thermal design of such configurations. More specifically, effects of channel height and width, streamwise jet-to-jet spacing, impingement hole staggering arrangements, varying jet diameters, convergent and divergent channel geometries, as well as effects of number of holes, are addressed for all channel interior surfaces. Existing correlations are also presented and compared to empirical models derived from traditional multi-array impingement jet systems. Furthermore, future research directions in the form of sequential impingement cascades are also discussed. NOMENCLATURE D jet diameter [m] P r Prandtl number [-] G j jet mass-velocity [kg/(m 2 s)] u velocity [m/s] G cf crossflow mass-velocity [kg/(m 2 s)] x, y, z coordinate system h heat transfer coefficient [W/(m 2 K)] X jet to jet spacing [m] N number of impingement holes [-] Y channel width [m] N u D Nusselt number based on jet diameter [-] ∆y jet staggering [m] Re D Reynolds number based on jet diameter [-] Z channel height [m]

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Experimental and numerical investigation of narrow impingement cooling channels

Cited by 50 publications

References 25 publications

Heat transfer characteristics of high crossflow impingement channels: Effect of number of holes

Heat transfer characteristics of high crossflow impingement channels: Effect of number of holes

A heat transfer analysis from a porous plate with transpiration cooling

Narrow impingement channels: recent advancements and future directions

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