Relationship between natural convection cooling performance and tilt angle of thin enclosure

2018 ◽  
Author(s):  
Shun Yonezuka ◽  
Takashi Fukue ◽  
Mamoru Kikuchi ◽  
Koichi Hirose ◽  
Qiang-Sheng Wang ◽  
...  
Keyword(s):  
Natural Convection ◽  
Tilt Angle ◽  
Cooling Performance ◽  
Convection Cooling

135 Relationship between Natural Convection Cooling Performance and Tilt Angle of Thin Enclosure

2018 ◽  
Vol 2018.53 (0) ◽  
pp. 67-68
Author(s):  
Shun Yonezuka ◽  
Takashi Fukue ◽  
Mamoru Kikuchi ◽  
Koichi Hirose ◽  
Yuji Okada ◽  
...  
Keyword(s):  
Natural Convection ◽  
Tilt Angle ◽  
Cooling Performance ◽  
Convection Cooling

Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling

1998 ◽  
Vol 120 (4) ◽  
pp. 840-857 ◽  
Author(s):  
M. P. Dyko ◽  
K. Vafai
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Three Dimensional ◽  
Convective Cooling ◽  
Cooling Flow ◽  
Physical Mechanisms ◽  
Braking System ◽  
Flow And Heat Transfer ◽  
Convection Cooling

A heightened awareness of the importance of natural convective cooling as a driving factor in design and thermal management of aircraft braking systems has emerged in recent years. As a result, increased attention is being devoted to understanding the buoyancy-driven flow and heat transfer occurring within the complex air passageways formed by the wheel and brake components, including the interaction of the internal and external flow fields. Through application of contemporary computational methods in conjunction with thorough experimentation, robust numerical simulations of these three-dimensional processes have been developed and validated. This has provided insight into the fundamental physical mechanisms underlying the flow and yielded the tools necessary for efficient optimization of the cooling process to improve overall thermal performance. In the present work, a brief overview of aircraft brake thermal considerations and formulation of the convection cooling problem are provided. This is followed by a review of studies of natural convection within closed and open-ended annuli and the closely related investigation of inboard and outboard subdomains of the braking system. Relevant studies of natural convection in open rectangular cavities are also discussed. Both experimental and numerical results obtained to date are addressed, with emphasis given to the characteristics of the flow field and the effects of changes in geometric parameters on flow and heat transfer. Findings of a concurrent numerical and experimental investigation of natural convection within the wheel and brake assembly are presented. These results provide, for the first time, a description of the three-dimensional aircraft braking system cooling flow field.

Flow Channelization Method to Enhance Transformer Radiator Cooling Capacity

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Subhashish Dasgupta ◽  
Anurag Nandwana ◽  
K. Ravikumar
Keyword(s):  
Natural Convection ◽  
Heat Exchangers ◽  
Fluid Dynamic ◽  
Cost Effective ◽  
Cooling Capacity ◽  
Structural Features ◽  
Cfd Analysis ◽  
Cooling Process ◽  
Effective Technology ◽  
Convection Cooling

Abstract Most oil-cooled equipment like transformers are provided with radiators or heat exchangers, for the heated oil to exchange heat with the surrounding air by natural convection cooling, assisting the overall cooling process. While such radiators are effective accessories in controlling equipment temperature rise, it is ever desirable to further enhance the cooling capacity by design modifications or incorporating simplistic and cost-effective cooling technologies. In this study, computational fluid dynamic (CFD) analysis has been performed to evaluate the possibility of improving radiator performance by flow channelizing structures. Significant benefits (up to 17% increase in heat transfer coefficient) of imposing such structures, like a top chimney and an enclosure surrounding the radiator, were obtained. Although several past studies have confirmed that natural convection cooling effect can be intensified by flow channelization, the phenomenon is unique to a particular application. Given the wide variety in applications, in terms of shape, size, and structural features, it is necessary to study the effect in a given application of interest. This study points to a new direction in enhancing the cooling capacity of transformer radiators, inducing flow channelization, an easy-to-implement and cost-effective technology. Further, the study offers interesting learnings regarding flow channelization effects, which are invaluable guidelines for designers of future radiators.

Natural Convection Heat Transfer Characteristics of Flat Plate Enclosures

1979 ◽  
Vol 101 (1) ◽  
pp. 120-125 ◽  
Author(s):  
K. R. Randall ◽  
J. W. Mitchell ◽  
M. M. El-Wakil
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Tilt Angle ◽  
Convection Heat Transfer ◽  
Transfer Coefficients ◽  
Number Range ◽  
Grashof Number ◽  
Average Heat ◽  
Plate Spacing

Heat transfer by natural convection in rectangular enclosures has been experimentally studied using interferometric techniques. The effects of Grashof number, tilt angle, and aspect ratio on both the local and average heat transfer coefficients have been determined. The Grashof number range tested was 4 × 103 to 3.1 × 105, and the aspect ratio (ratio of enclosure length to plate spacing) varied between 9 and 36. The angles of tilt of the enclosure with respect to the horizontal were 45, 60, 75 and 90 deg. Correlations are developed for both local and average Nusselt number over the range of test variables. The effect of tilt angle is found to reduce the average heat transfer by about 18 percent from the value of 45 deg to that at 90 deg. No significant effect of aspect ratio over the range tested was found. A method for characterizing the flow regimes that is based on heat transfer mechanisms is proposed.

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