Performance of Axial Fans in Close Proximity to the Electromagnetic Compatibility Screens

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
R. Antón ◽  
A. Bengoechea ◽  
A. Rivas ◽  
J. C. Ramos ◽  
G. S. Larraona
Keyword(s):  
Flow Rate ◽  
Electromagnetic Compatibility ◽  
Perforated Plate ◽  
The Other ◽  
Geometrical Parameters ◽  
Rate Reduction ◽  
Fan Performance ◽  
Close Proximity ◽  
Axial Fans ◽  
Good Guide

The performance of axial fans in close proximity to the electromagnetic compatibility (EMC) screens was analyzed by means of an experimental parametric study. The following geometrical parameters were studied: the hub-to-tip ratio, the ratio between fan thickness and fan diameter, the porosity and thickness of the perforated plate, and finally, the distance between the perforated plate and the inlet and the outlet of the fan. Screen porosity was found to be the most important parameter. Fan performance degradation is expressed by means of two correlations: one for the deterioration in the fan pressure at the no-flow point and the other for the flow rate reduction at the free delivery point. Both correlations were formulated as functions of screen porosity and the distance between the fan and the screen. We believe that the correlations can serve as a good guide for correct fan placement in a telecommunications cabinet.

A Comparison of Two Alternative Methods for Defining Fan Performance

1982 ◽  
Vol 104 (1) ◽  
pp. 177-183 ◽  
Author(s):  
P. M. Gerhart ◽  
R. Jorgensen ◽  
J. Kroll
Keyword(s):  
Flow Rate ◽  
Total Pressure ◽  
Performance Test ◽  
Static Pressure ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
The Other ◽  
Alternative Methods ◽  
Performance Variables ◽  
Fan Performance

PTC 11 Committee, the ASME Performance Test Code Committee charged with producing a new test code for large industrial fans, has decided to present code users with two options for expressing fan performance. While one of these options is representative of current U.S. practice, the other option appears to be quite different. The differences center around the definitions of fan flow rate and fan output. Historically, fan flow rate has been defined as the volume flow rate at the fan inlet, and fan output has been defined as either the rise in total pressure across the fan or as the rise from the total pressure at the inlet to the static pressure at the outlet. The alternative method uses the mass flow rate and the “fan specific energy” as the performance variables. If the fan process is incompressible, the two sets of variables produce easily reconciled values; however, if compressibility must be accounted for, subtle differences may arise. This paper examines the assumptions and developments of the two alternative methods of expressing fan performance.

Effect on Inlet Vent Porosity on Fan Characteristic Performance for Electronics Cooling

2009 ◽  
Author(s):  
Takashi Fukue ◽  
Katsuhiro Koizumi ◽  
Masaru Ishizuka ◽  
Shinji Nakagawa
Keyword(s):  
Flow Rate ◽  
Perforated Plate ◽  
Electronics Cooling ◽  
Maximum Flow ◽  
Flow Area ◽  
Flow Rates ◽  
Fan Performance ◽  
Performance Metric ◽  
Cooling Fans ◽  
The Relationship

Critical fan performance metric such as characteristic output curves and maximum flow rates are affected by various environmental conditions where cooling fans are installed. This paper describes the relationship between the fan performance and configuration factors such as the flow inlet porosity of electronic enclosure, the flow obstacles which imitate high-density packages and narrow flow area configurations. We installed a test enclosure in front of a test fan and measured P-Q curves of the test fan, which were operated in the enclosure. The experiments, it was observed that the pressure difference was increased in the enclosure by the effects of a wall. We installed a perforated plate in front of the fan as an obstacle and investigated how this changed the P-Q curve. In general, addition of the perforated plate in front of the fan decreased the characteristic output of the fan. On the other hand, the flow rate by the fan supply was decreased by the existence of the narrow inlet or obstacles. When an opening area in front of a fan became smaller than double of the fan flow area, the flow rate was significantly decreased. In addition, it was observed that the maximum flow rate depended on the opening area ratio. Finally, a model for predicting flow rates decreases by the enclosure inlet and obstacles was proposed.

Study on P-Q Curves of Cooling Fans for Thermal Design of Electronic Equipment (Effects of Opening Position of Obstructions Near a Fan)

2011 ◽  
Author(s):  
Takashi Fukue ◽  
Masaru Ishizuka ◽  
Tomoyuki Hatakeyama ◽  
Shinji Nakagawa ◽  
Katsuhiro Koizumi
Keyword(s):  
Flow Rate ◽  
Perforated Plate ◽  
Pressure Rise ◽  
High Density ◽  
Thermal Design ◽  
Electronic Equipment ◽  
Flow Passage ◽  
Fan Performance ◽  
Cooling Fan ◽  
Cooling Fans

This study describes an operation pressure and supplies flow rate of an axial cooling fan installed in high-density packaging electronic equipment. Fan performance is generally defined by their P-Q curve, specifically, a relationship between fan pressure rise (ΔP) and flow rate (Q). A compact cooling fan often operates in a high-density mounting device, which may decrease the fan performance. In this study, we focus on an obstruction near a fan, which is electronic components such as PCBs, capacitors and heat sinks, as one of a factor which decreases fan performance. We installed a perforated plate which simulated the above components near a fan and measured the P-Q curve. To investigate a relationship between a fan performance decrease and an opening position near the fan, a part of the perforated plate was closed. Closed position was changed and explored an opening condition which caused the dominant fan performance decrease. From experiments, it was found that the fan performance was decreased when flow passage in front of a fan was blocked by an obstruction. Especially, when flow passage in front of a fan hub was blocked, a dominantly reduction of fan pressure was caused. An obstruction rear a fan has no effect on a fan performance curve itself. In addition, opening conditions in front of a fan tip had a little influence on a fan pressure characteristic when there was no obstruction in front of a hub.

Severe Drooling and Treatment With Botulinum Toxin

2012 ◽  
Vol 21 (1) ◽  
pp. 15-21
Author(s):  
Merete Bakke ◽  
Allan Bardow ◽  
Eigild Møller
Keyword(s):  
Botulinum Toxin ◽  
Side Effects ◽  
Health Risk ◽  
Flow Rate ◽  
Clinical Evidence ◽  
Acetylcholine Release ◽  
Psychosocial Problems ◽  
Rate Reduction ◽  
Local Inhibition ◽  
Surgical Treatments

Severe drooling is associated with discomfort and psychosocial problems and may constitute a health risk. A variety of different surgical and non-surgical treatments have been used to diminish drooling, some of them with little or uncertain effect and others more effective but irreversible or with side effects. Based on clinical evidence, injection with botulinum toxin (BTX) into the parotid and submandibular glands is a useful treatment option, because it is local, reversible, and with few side effects, although it has to be repeated. The mechanism of BTX is a local inhibition of acetylcholine release, which diminishes receptor-coupled secretion and results in a flow rate reduction of 25–50% for 2–7 months.

scholarly journals The Properties of Cu Ions in Zeolites CuY Studied by IR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4686
Author(s):  
Jerzy Podobiński ◽  
Mariusz Gackowski ◽  
Grzegorz Mordarski ◽  
Katarzyna Samson ◽  
Michał Śliwa ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Positive Charge ◽  
Co Adsorption ◽  
The Other ◽  
Probe Molecules ◽  
Adsorption And Desorption ◽  
Other Hand ◽  
Close Proximity ◽  
No And Co Adsorption ◽  
Cu Ions

The properties of both Cu2+ and Cu+ ions in zeolite CuY were followed with NO and CO as probe molecules. Cu2+ was found to be located in SII, SII*, and SIII sites, whereas Cu+ was found in SII and SII* sites. The fine analysis of the spectra of Cu2+-NO and Cu+-CO adducts suggests that both in SII and in SII* sites two kinds of Cu cations exist. They differ in the positive charge, which may be related to the varying numbers of AlO4− in close proximity. The experiments of NO and CO adsorption and desorption evidenced that both Cu2+ and Cu+ sites of highest positive charge bind probe molecules most strongly but activate them to a lesser extent than the Cu sites of lowest positive charge. The experiments of reduction with hydrogen evidenced that the Cu ions of higher positive charge are first reduced by hydrogen. On the other hand, Cu sites of the lowest positive charge are first oxidized by oxygen. The experiments with CuNaY zeolites of various Cu contents suggest that the first introduced Cu (at low Cu contents) created Cu+, which was the most neutralized by framework oxygens. Such Cu cations are the most stabilized by framework oxygens.

scholarly journals The Effect of Route Choice in Children’s Exposure to Ultrafine Particles Whilst Walking to School

2021 ◽  
Vol 18 (15) ◽  
pp. 7808
Author(s):  
Mehrdad Rafiepourgatabi ◽  
Alistair Woodward ◽  
Jennifer A. Salmond ◽  
Kim Natasha Dirks
Keyword(s):  
Ultrafine Particles ◽  
Route Choice ◽  
The Other ◽  
Close Proximity ◽  
Public Health Officials ◽  
Risk Of Exposure ◽  
The Mean ◽  
Walking To School ◽  
Elevated Exposure ◽  
Children’S Exposure

Children walking to school are at a high risk of exposure to air pollution compared with other modes because of the time they spend in close proximity to traffic during their commute. The aim of this study is to investigate the effect of a walker’s route choice on their exposure to ultrafine particles (UFP) on the walk to school. During morning commutes over a period of three weeks, exposure to UFP was measured along three routes: two routes were alongside both sides of a busy arterial road with significantly higher levels of traffic on one side compared to the other, and the third route passed through quiet streets (the background route). The results indicate that the mean exposure for the pedestrian walking along the background route was half the exposure experienced on the other two routes. Walkers on the trafficked side were exposed to elevated concentrations (>100,000 pt/cc) 2.5 times longer than the low-trafficked side. However, the duration of the elevated exposure for the background route was close to zero. Public health officials and urban planners may use the results of this study to promote healthier walking routes to schools, especially those planned as part of organized commutes.

scholarly journals Energy Loss in Steep Open Channels with Step-Pools

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 72
Author(s):  
Suresh Kumar Thappeta ◽  
S. Murty Bhallamudi ◽  
Venu Chandra ◽  
Peter Fiener ◽  
Abul Basar M. Baki
Keyword(s):  
Energy Loss ◽  
Flow Rate ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Nonlinear Function ◽  
Open Channels ◽  
Geometrical Parameters ◽  
Transition Flow ◽  
Cumulative Energy ◽  
Zone Velocity

Three-dimensional numerical simulations were performed for different flow rates and various geometrical parameters of step-pools in steep open channels to gain insight into the occurrence of energy loss and its dependence on the flow structure. For a given channel with step-pools, energy loss varied only marginally with increasing flow rate in the nappe and transition flow regimes, while it increased in the skimming regime. Energy loss is positively correlated with the size of the recirculation zone, velocity in the recirculation zone and the vorticity. For the same flow rate, energy loss increased by 31.6% when the horizontal face inclination increased from 2° to 10°, while it decreased by 58.6% when the vertical face inclination increased from 40° to 70°. In a channel with several step-pools, cumulative energy loss is linearly related to the number of step-pools, for nappe and transition flows. However, it is a nonlinear function for skimming flows.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

Optimization of Inlet Ring Groove Arrangement for Suppression of Unstable Flow in a Centrifugal Impeller

2005 ◽  
Author(s):  
Masahiro Ishida ◽  
Daisaku Sakaguchi ◽  
Hironobu Ueki
Keyword(s):  
Flow Rate ◽  
The Other ◽  
Centrifugal Impeller ◽  
Shape Parameters ◽  
Unstable Flow ◽  
Ring Groove ◽  
Flow Rates ◽  
Small Flow ◽  
Specific Speed ◽  
Large Flow

An optimization of the inlet ring groove arrangement has been pursued in the present study for obtaining better impeller characteristics and a wider operation range at both small and large flow rates in a high specific speed type centrifugal impeller with inducer. The effects of the shape parameters with respect to the inlet ring groove on the impeller characteristic and the flow incidence were analyzed mainly based on numerical simulations, but also compared to the experimental results. At small flow rates, a significant improvement in the impeller characteristic is achieved due to reduction in the excessive-positive flow incidence by optimizing both location and width of the rear groove near the inducer tip throat. On the other hand, the impeller characteristic is improved at large flow rates by implementing the corner radius at the rear groove edge and by placing another front ring groove in the suction pipe. As a result, by the optimized configuration of the front and rear ring grooves, the unstable flow range of the test impeller can be reduced by about 50% without deterioration of the impeller characteristic even at the 125% flow rate.

scholarly journals Non-philosophical Christ-poetics beyond the mystical turn in conversation with continental philosophy of religion

2016 ◽  
Vol 72 (3) ◽  
Author(s):  
Johann-Albrecht Meylahn
Keyword(s):  
Philosophy Of Religion ◽  
Continental Philosophy ◽  
The Other ◽  
Negative Theology ◽  
The Uncanny ◽  
Close Proximity ◽  
Mystical Theology ◽  
Critical Conversation ◽  
Language Text ◽  
The Way

The religious turn in continental philosophy has opened the door for postmetaphysical mystical theology. Postmetaphysical mystical theology seeks to understand the non-relation relation of language (text) to the Other. Yet, this non-relation relation to the Other, who is every other, can also be interpreted differently to the mystical understanding. For example, Žižek argues that the Other, which is often experienced as the uncanny, the unpredictable and the contingent (lived spirituality), is not necessarily the result of some mystical unknowable Otherness but is a consequence of the way the subject’s own activity is inscribed into reality. These experiences of lived spirituality or experiences of Otherness can, rather than being interpreted as an in-breaking of the mystical Other, be interpreted otherwise, as a grammatological consequence of the inability and impossibility of language (Lacan). Therefore, in this article, Žižek’s thoughts function as a bridge to bring this mystical turn back into critical conversation with continental philosophy and particularly with the thoughts of Derrida, Laruelle and Stiegler. The contemporary mystical turn in theology rediscovers something of this non-religious religion. Derrida’s thoughts are in close proximity to negative theology and yet there is an important difference. This difference will be explored and further developed towards Laruelle’s non-philosophy, which does not translate into a non-religion religion or postmetaphysical metaphysics but remains a non-philosophy or maybe a science of Christ. This article will conclude with a tentative exploration of a postmetaphysical Christ-poetics beyond the mystical turn.

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