Influence of Radiation and Viscous Dissipation on Three-Dimensional Fluctuating Couette Flow and Heat Transfer with Suction/Injection

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.

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Three-dimensional modelling of fluid flow and heat transfer in micro-channels with synthetic jet

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2011.09.003 ◽

2012 ◽

Vol 55 (1-3) ◽

pp. 198-213 ◽

Cited By ~ 23

Author(s):

A. Lee ◽

V. Timchenko ◽

G.H. Yeoh ◽

J.A. Reizes

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Three Dimensional ◽

Synthetic Jet ◽

Flow And Heat Transfer ◽

Micro Channels

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Numerical Simulation of Gas Flow and Heat Transfer in Cross-Wavy Primary Surface Channel for Microtubine Recuperators

Volume 3: Turbo Expo 2005, Parts A and B ◽

10.1115/gt2005-68292 ◽

2005 ◽

Cited By ~ 6

Author(s):

H. X. Liang ◽

Q. W. Wang ◽

L. Q. Luo ◽

Z. P. Feng

Keyword(s):

Heat Transfer ◽

Numerical Simulation ◽

Gas Turbine ◽

Numerical Study ◽

High Reliability ◽

Three Dimensional ◽

Operating Conditions ◽

Flow And Heat Transfer ◽

High Heat Transfer ◽

The Cross

Three-dimensional numerical simulation was conducted to investigate the flow field and heat transfer performance of the Cross-Wavy Primary Surface (CWPS) recuperators for microturbines. Using high-effective compact recuperators to achieve high thermal efficiency is one of the key techniques in the development of microturbine in recent years. Recuperators need to have minimum volume and weight, high reliability and durability. Most important of all, they need to have high thermal-effectiveness and low pressure-losses so that the gas turbine system can achieve high thermal performances. These requirements have attracted some research efforts in designing and implementing low-cost and compact recuperators for gas turbine engines recently. One of the promising techniques to achieve this goal is the so-called primary surface channels with small hydraulic dimensions. In this paper, we conducted a three-dimensional numerical study of flow and heat transfer for the Cross-Wavy Primary Surface (CWPS) channels with two different geometries. In the CWPS configurations the secondary flow is created by means of curved and interrupted surfaces, which may disturb the thermal boundary layers and thus improve the thermal performances of the channels. To facilitate comparison, we chose the identical hydraulic diameters for the above four CWPS channels. Since our experiments on real recuperators showed that the Reynolds number ranges from 150 to 500 under the operating conditions, we implemented all the simulations under laminar flow situations. By analyzing the correlations of Nusselt numbers and friction factors vs. Reynolds numbers of the four CWPS channels, we found that the CWPS channels have superior and comprehensive thermal performance with high compactness, i.e., high heat transfer area to volume ratio, indicating excellent commercialized application in the compact recuperators.

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