Effect of variations in Streamwise Spacing and Length on convection from Surface-Mounted Rectangular Components
TL;DR: In this paper, the effect of variations in streamwise spacing and component length on convection from rectangular, surface-mounted components in a channel flow is reported and local heat transfer measurements are made using an interferometer.
Abstract: The effect of variations in streamwise spacing and component length on convection from rectangular, surface-mounted components in a channel flow are reported. Component dimensions are the same order of magnitude as the channel wall-to-wall spacing. The channel Reynolds number, with air as the coolant, ranged from 670 to 3000. Flow visualization showed that under the above conditions the channel flow is transitional. The effect of variations in component streamwise spacing on the level of turbulence in the channel and on the interaction between the core of the channel flow and the recirculating flow in cavities between components is discussed. Pressure drop measurements show that the dominant loss mechanism is due to form drag caused by the components. Local heat transfer measurements are made using an interferometer. Analysis of the results shows that the overall heat transfer is properly correlated in terms of a flow Reynolds number based on the component length. At small-component Reynolds number, the o...
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TL;DR: The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones on the thermal control of semiconductor devices, modules, and total systems.
Abstract: Publisher Summary Thermal control of electronic components has one principal objective, to maintain relatively constant component temperature equal to or below the manufacturer's maximum specified service temperature, typically between 85 and 100°C. It is noted that even a single component operating 10°C beyond this temperature can reduce the reliability of certain systems by as much as 50%. Therefore, it is important for the new thermal control schemes to be capable of eliminating hot spots within the electronic devices, removing heat from these devices and dissipating this heat to the surrounding environment. Several strategies have developed over the years for controlling and removing the heat generated in multichip modules, which include advanced air-cooling schemes, direct cooling, and miniature thermosyphons or free-falling liquid films. The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones. The chapter focuses on investigations performed over the past decade and includes information on the thermal control of semiconductor devices, modules, and total systems.
285 citations
TL;DR: In this article, a three-dimensional numerical simulation has been performed for flows over a backward-facing step at low Reynolds number in order to investigate the effects of the duct aspect ratio.
116 citations
TL;DR: In this article, the authors measured the local forced convective heat transfer characteristics of an array of two-dimensional discrete heat sources and found that protruding heat sources yield higher heat transfer than flush-mounted heat sources at the same channel Reynolds number.
69 citations
IBM1
TL;DR: In this paper, the authors compare the results of a detailed CFD model of a heat sink with experimental data and present a technique for representing the heat sink in a coarse manner.
Abstract: CFD modelling of electronic components becomes increasingly more important as CFD spreads into the design process. This paper compares the results of a detailed CFD model of a heat sink with experimental data. Then a technique for representing the heat sink in a coarse manner in a CFD model is presented and compared with the detailed CFD model. Agreement is quite good, indicating that this technique can be used when representing heat sinks in larger card or system models. >
48 citations
TL;DR: Two general turbulence models, the standard k-ϵ model and the Reynolds stress model (RSM), were used to predict the forced convection of a fully developed turbulent flow through an assembly of two horizontally oriented parallel plates in the Reynolds number range.
Abstract: Two general turbulence models, the standard k–ϵ model and the Reynolds stress model (RSM), were used to predict the forced convection of a fully developed turbulent flow through an assembly of two horizontally oriented parallel plates in the Reynolds number range 22,000 < Re D < 94,000. The upper smooth plate was thermally insulated, whereas the bottom plate, attached with rectangular-cross-sectional ribs perpendicular to the mean air flow, was provided with a uniform heat flux. The ribs were uniformly spaced with the pitch-to-height ratio of p/e = 4, a height-to-hydraulic-diameter ratio of e/D = 0.25, and a width-to-height ratio of w/e = 2. The numerical approaches were based on the finite-volume technique. A second-order upwind scheme was applied in the calculation and a very fine mesh density was arranged in the regions near the wall boundaries. The SIMPLE algorithm was adopted to handle the pressure–velocity coupling in the calculation. Local Nusselt number distribution along the heated bott...
39 citations
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TL;DR: In this article, a detailed experimental study of turbulent boundary-layer development over rough walls in both zero and adverse pressure gradients is described, where the skin friction was determined by pressure tapping the roughness elements and measuring their form drag.
Abstract: This paper describes a detailed experimental study of turbulent boundary-layer development over rough walls in both zero and adverse pressure gradients. In contrast to previous work on this problem the skin friction was determined by pressure tapping the roughness elements and measuring their form drag.Two wall roughness geometries were chosen each giving a different law of behaviour; they were selected on the basis of their reported behaviour in pipe flow experiments. One type gives a Clauser type roughness function which depends on a Reynolds number based on the shear velocity and on a length associated with the size of the roughness. The other type of roughness (typified by a smooth wall containing a pattern of narrow cavities) has been tested in pipes and it is shown here that these pipe results indicate that the corresponding roughness function does not depend on roughness scale but depends instead on the pipe diameter. In boundary-layer flow the first type of roughness gives a roughness function identical to pipe flow as given by Clauser and verified by Hama and Perry & Joubert. The emphasis of this work is on the second type of roughness in boundary-layer flow. No external length scale associated with the boundary layer that is analogous to pipe diameter has been found, except perhaps for the zero pressure gradient case. However, it has been found that results for both types of roughness correlate with a Reynolds number based on the wall shear velocity and on the distance below the crests of the elements from where the logarithmic distribution of velocity is measured. One important implication of this is that a zero pressure gradient boundary layer with a cavity type rough wall conforms to Rotta's condition of precise self preserving flow. Some other implications of this are also discussed.
548 citations
TL;DR: In this article, the effects of rib shape, angle of attack and pitch-to-height ratio on friction factor and heat transfer were investigated on a rib-roughened surface.
512 citations
TL;DR: In this article, a multi-faceted experimental investigation has been carried out to study heat transfer and pressure drop for airflow in arrays of heat generating rectangular modules deployed along one wall of a flat rectangular duct.
213 citations
TL;DR: In this article, the authors investigate the heat transfer and fluid flow characteristics of arrays of heat-generating, block-like modules affixed to one wall of a parallel-plate channel and cooled by forced convection airflow.
116 citations
TL;DR: Etude experimentale du refroidissement par convection de dispositifs electroniques constitues de differents modules is described in this paper, where influence de modules de hauteurs differentes ou d'espacements entre les modules are discussed.
61 citations