A Theoretical and Experimental Investigation of the Scaling of Micro Fan Performance

2003 ◽  
Author(s):  
Ronan Grimes ◽  
David Quin ◽  
Ed Walsh ◽  
Mark Davies ◽  
Stefan Kunz
Keyword(s):  
Experimental Investigation ◽  
Mobile Phones ◽  
Electronic Systems ◽  
Potential Solution ◽  
Micro Scale ◽  
Fan Performance ◽  
Electro Discharge Machining ◽  
Macro Scale ◽  
Cooling Fans ◽  
Processor Speed

Mobile phones and palm top computers are following trends of increased functionality and processor speed. To allow these trends to continue, compact cooling solutions are required. One potential solution is to introduce cooling fans. However, no fan currently exists which is small enough. This paper investigates the feasibility of producing a fan on the micro scale, which could be used. Theoretical analysis predicts a reduction in efficiency as fan size is reduced. A series of geometrically similar fans was produced so that the scaling could be experimentally investigated. These fans varied in size from the macro to the micro scale. The macro scale fan, which was used as a datum, is typical of those used to cool macro scale electronic systems. The authors developed techniques for the fabrication of the smaller scale fans. These included micro electro discharge machining. Methods for testing the performance of each of these fans were also developed. The pressure flow performance of each of the fans is measured, and confirms that as the micro scale is approached fan efficiency decreases. The observed decrease in efficiency is in agreement with theoretical prediction.

Scaling the Performance of Micro-Fans

2003 ◽  
Author(s):  
R. Grimes ◽  
E. Walsh ◽  
S. Kunz ◽  
M. Davies ◽  
D. Quin
Keyword(s):  
Numerical Simulations ◽  
Radial Flow ◽  
Three Dimensional ◽  
Axial Flow ◽  
Scaling Analysis ◽  
Electronic Systems ◽  
Two Dimensional ◽  
Local Loss ◽  
Micro Scale ◽  
Fan Performance

Pumping of liquids and gases in micro fluidic systems has been the focus of much attention in recent times. Miniaturisation of traditional rotating pumps such as axial and radial flow designs, has been limited by the fabrication techniques employed. As a result of these limitations, the geometry of the majority of rotating micro pumps has been two-dimensional. This paper addresses issues of scaling in micro axial flow fans. The anticipated primary application will be in cooling compact electronic systems, but the results are applicable to a much wider range of pumping applications. Using novel fabrication techniques a series of geometrically similar three dimensional fans were fabricated, ranging in size from the macro to the micro scale. Experimental techniques are described which will be used for the characterisation of these fans. A scaling analysis is used to show how reduced fan scale causes increased local loss as fan dimensions are reduced to the micro scale. Numerical simulations of flow in the channels between the fan blades were performed to investigate the validity of the scaling theory, the results of which give confidence in the scaling analysis. The fundamental finding of this work is that a reduction in scale is accompanied by a reduction in efficiency and thus fan performance.

scholarly journals Experimental Investigation of Relative Permeability Upscaling from the Micro-Scale to the Macro-Scale

2003 ◽  
Author(s):  
Laura J. Pyrak-Nolte ◽  
JiangTao Cheng ◽  
Ping Yu ◽  
Nicholas Giordano ◽  
Mirela Mustata ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Relative Permeability ◽  
Micro Scale ◽  
Macro Scale ◽  
Permeability Upscaling

scholarly journals EXPERIMENTAL INVESTIGATION OF RELATIVE PERMEABILITY UPSCALING FROM THE MICRO-SCALE TO THE MACRO-SCALE

2002 ◽  
Author(s):  
Laura J. Pyrak-Nolte ◽  
Ping Yu ◽  
JiangTao Cheng ◽  
Daiquan Chen ◽  
Nicholas Giordano ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Relative Permeability ◽  
Micro Scale ◽  
Macro Scale ◽  
Permeability Upscaling

scholarly journals Experimental Investigation of Relative Permeability Upscaling from the Micro-Scale to the Macro-Scale

2001 ◽  
Author(s):  
Ping Yu ◽  
Nicholas Giodao ◽  
JiangTao Cheng ◽  
Mirela Mustata ◽  
William Headley ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Relative Permeability ◽  
Micro Scale ◽  
Macro Scale ◽  
Permeability Upscaling

scholarly journals EXPERIMENTAL INVESTIGATION OF RELATIVE PERMEABILITY UPSCALING FROM THE MICRO-SCALE TO THE MACRO-SCALE

2001 ◽  
Author(s):  
JiangTao Cheng ◽  
Ping Yu ◽  
William Headley ◽  
Nicholas Giordao ◽  
Mirela Mustata ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Relative Permeability ◽  
Micro Scale ◽  
Macro Scale ◽  
Permeability Upscaling

scholarly journals 2D-wavelet based micro and macro texture analysis for asphalt pavement under snow or ice condition

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Feng Li ◽  
Gulnigar Ablat ◽  
Siqi Zhou ◽  
Yixin Liu ◽  
Yufeng Bi ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Micro Scale ◽  
Braking System ◽  
Macro Scale ◽  
Texture Characteristics ◽  
The Mean ◽  
Resistance Performance

AbstractIn ice and snow weather, the surface texture characteristics of asphalt pavement change, which will significantly affect the skid resistance performance of asphalt pavement. In this study, five asphalt mixture types of AC-5, AC-13, AC-16, SMA-13, SMA-16 were prepared under three conditions of the original state, ice and snow. In this paper, a 2D-wavelet transform approach is proposed to characterize the micro and macro texture of pavement. The Normalized Energy (NE) is proposed to describe the pavement texture quantitatively. Compared with the mean texture depth (MTD), NE has the advantages of full coverage, full automation and wide analytical scale. The results show that snow increases the micro-scale texture because of its fluffiness, while the formation of the ice sheets on the surface reduces the micro-scale texture. The filling effect of snow and ice reduces the macro-scale texture of the pavement surface. In a follow-up study, the 2D-wavelet transform approach can be applied to improve the intelligent driving braking system, which can provide pavement texture information for the safe braking strategy of driverless vehicles.

Spatial-Pattern-Induced Evolution of a Self-Replicating Loop Network

2006 ◽  
Vol 12 (4) ◽  
pp. 461-485 ◽  
Author(s):  
Keisuke Suzuki ◽  
Takashi Ikegami
Keyword(s):  
Pattern Formation ◽  
Spatial Pattern ◽  
Spatial Patterns ◽  
Spiral Structure ◽  
Scale Interactions ◽  
Micro Scale ◽  
Macro Scale ◽  
Loop Network ◽  
Spatial Pattern Formation

We study a system of self-replicating loops in which interaction rules between individuals allow competition that leads to the formation of a hypercycle-like network. The main feature of the model is the multiple layers of interaction between loops, which lead to both global spatial patterns and local replication. The network of loops manifests itself as a spiral structure from which new kinds of self-replicating loops emerge at the boundaries between different species. In these regions, larger and more complex self-replicating loops live for longer periods of time, managing to self-replicate in spite of their slower replication. Of particular interest is how micro-scale interactions between replicators lead to macro-scale spatial pattern formation, and how these macro-scale patterns in turn perturb the micro-scale replication dynamics.

scholarly journals Experimental study of the effects of wire EDM on the characteristics of ferritic steel, at a micro-scale on the contour cut surface

2018 ◽  
Vol 115 (4) ◽  
pp. 413
Author(s):  
Nida Naveed
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Surface Characteristics ◽  
Surface Damage ◽  
Cutting Process ◽  
Contour Method ◽  
X Ray Diffraction ◽  
Micro Scale ◽  
Macro Scale ◽  
Cut Surface

This study, on a micro-scale, of the WEDM cut surfaces of specimens to which the contour method of residual stress measurement is being applied provides detailed information about the effects of the cutting process on the surface quality. This is defined by a combination of several parameters: variation in surface contour profile, sub-surface damage and surface texture. Measurements were taken at the start, the middle and at the end of the cut. This study shows that during WEDM cutting, a thin layer, extending to a depth of a few micrometres below the surface of the cut, is transformed. This layer is known as the recast layer. Using controlled-depth etching and X-ray diffraction, it is shown that this induces an additional tensile residual stress, parallel to the plane of the cut surface. The WEDM cut surface and sub-surface characteristics are also shown to vary along the length of the cut. Moreover, these micro-scale changes were compared with macro-scale residual stress results and provides an indication of the point at which the changes occurred by cutting process can be significantly relative to the macro-scale residual stress in a specimen.

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