Flow Induced by a Two Stage Electrohydrodynamic Gas Pump in a Square Channel

2020 ◽  
Author(s):  
A. K. M. Monayem H. Mazumder ◽  
Grace S. Trombley ◽  
Brendon G. Cusinio
Keyword(s):  
Velocity Profile ◽  
Cross Sections ◽  
Volume Flow Rate ◽  
Forced Flow ◽  
Tube Length ◽  
Two Stage ◽  
Maximum Enhancement ◽  
Square Channel ◽  
Parabolic Velocity Profile ◽  
Wide Range

Abstract In this study, fluid flow induced by a two stage electrohydrodynamic (EHD) gas pump in a square channel has been evaluated by experimental measurement and numerical simulations. This study is implemented for a two stage EHD gas pump with three emitting electrode configurations: 8, 24, and 56 respectively to seek the relation between the number of stages and emitting electrodes. The EHD pump is evaluated for a wide range of operating voltages starting from 20 kV up to 28 kV for further improvement in its performance over a single stage. To achieve the maximum enhancement, the emitting electrodes of the EHD gas pump are flush mounted on the channel walls so that the corona wind produced directly disturbs the boundary layer thickness and improves the heat transfer. This is leading to a higher velocity near the channel walls and resulting in an inverted parabolic velocity profile at the center of the channel, which is opposite to the fully developed velocity profile of a forced flow. Velocities are measured at three cross-sections along the tube length and then integrated to obtain the volume flow rate. The results show that EHD technique has a great potential for many engineering applications.

Enhanced Forced Convection in a Square Channel With Two-Stage Corona Wind Generator

2012 ◽  
Author(s):  
A. K. M. Monayem H. Mazumder ◽  
F. C. Lai
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Management ◽  
Forced Convection ◽  
Two Stage ◽  
Maximum Enhancement ◽  
Square Channel ◽  
Wind Generator ◽  
Wide Range ◽  
Corona Wind

In this study, enhancement in forced convection inside a square channel by a two-stage electrohydrodynamic (EHD) gas pump has been examined by numerical simulations. The EHD gas pump with 28 emitting electrodes in each stage has been evaluated for a wide range of operating voltages starting from the corona threshold voltage up to 28 kV for further improvement in its performance over that of a single-stage. To achieve the maximum enhancement in heat transfer, the emitting electrodes of the corona wind generator are flush mounted on the channel walls so that the corona wind produced directly perturbs the boundary layer. The results show that EHD technique has a great potential for applications in thermal management.

scholarly journals Investigation on the Nonconstant Behavior of a Vortex Flow Meter with Narrow Gauge Pipe via Conducting Measurements and Numerical Simulations

1970 ◽  
Vol 61 (3) ◽  
pp. 247
Author(s):  
Bence Fenyvesi ◽  
Csaba Horváth
Keyword(s):  
Numerical Simulations ◽  
Cross Sections ◽  
Flow Measurement ◽  
Vortex Flow ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Diagnostic Investigation ◽  
Number Range ◽  
Wide Range ◽  
The Given

Vortex shedding flowmeters can be used for a wide range of flow measurement applications with various kinds of fluids. The critical point in applying this method comes from the assumption that the Strouhal number is constant for the given Reynolds number range. In some cases – typically regarding flowmeters with narrow gauge pipes –, this assumption is only partially met, thus limiting the widespread use of these instruments in certain industrial appliances. The paper presents a diagnostic investigation on the effects of this nonconstant behavior. The method elaborated in this report can be applied to vortex flowmeters with narrow gauge pipes. In these instruments – usually due to the narrow cross-sections of the gauge pipe – measurement possibilities are limited, thus it is not possible for the user to determine the effects of the nonconstant behavior. To conduct these investigations, a calibration rig was designed and assembled. The presented diagnostic method combines measurements and numerical simulations. The results of the investigations can be used in the data processing phase, in order to reduce the uncertainty of the volume flow rate measured by vortex flowmeters.

EHD-Induced Flow in a Square Channel With Two-Stage Electrodes

2012 ◽  
Author(s):  
A. K. M. Monayem H. Mazumder ◽  
F. C. Lai ◽  
Y.-T. Chou
Keyword(s):  
Maximum Velocity ◽  
Gas Flows ◽  
Transfer Enhancement ◽  
Two Stage ◽  
Square Channel ◽  
Wide Range ◽  
Cooling Fans ◽  
Induced Flow ◽  
Conventional Cooling ◽  
Better Than

In this study flow field inside a square channel with a two-stage electrohydrodynamic (EHD) gas pump has been critically examined by experimental measurement and numerical simulation. The EHD gas pump with 28 emitting electrodes in each stage is tested for a wide range of operating voltages starting from the corona threshold voltage up to 28 kV for further improvement in its performance over that of a single-stage. It has been shown that the two-stage EHD gas pump can produce and sustain gas flows with a maximum velocity of 5 m/s. Its maximum performance of 34 L/s/W is better than that of conventional cooling fans used in personal computers. The implication for its application in thermal management and heat transfer enhancement has also been discussed.

Enhancement in Forced Convection by a Two Stage Corona Wind Generator

2020 ◽  
Author(s):  
A. K. M. Monayem H. Mazumder
Keyword(s):  
Forced Convection ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Temperature Fields ◽  
Two Stage ◽  
Power Requirement ◽  
Maximum Increase ◽  
Square Channel ◽  
Wide Range ◽  
Volume Method

Abstract In this study, forced convection enhancement in a square channel by a two stage electrohydrodynamic (EHD) gas pump is numerically analyzed. This study is implemented for a two stage EHD gas pump with three emitting electrode configurations: 8, 24, and 56 respectively to seek their effectiveness in the enhancement of forced convection and pumping power requirement. The EHD gas pump is evaluated for a wide range of operating voltages starting from 20 kV up to 28 kV. The influence of electric field on the flow and temperature fields is also examined for a wide range of Reynolds numbers. The three-dimensional governing equations for the flow and temperature fields are solved using the finite volume method. The Reynolds numbers (Re) considered in this study varies in a range between 100 and 2000. At Re = 100, a maximum increase of 42% in the average Nusselt number is achieved with an applied voltage of 28 kV. The overall effectiveness of the EHD gas pump in heat transfer enhancement is evaluated by the thermal hydraulic performance parameter, (Nu/Nu0)/(f/f0), which is always greater than unity. These results disclose that EHD technique has a great potential for many engineering applications, particularly for thermal management.

Flow Characteristics in a Channel With Corona Wind Generator

2010 ◽  
Author(s):  
J. Zhang ◽  
F. C. Lai
Keyword(s):  
Volume Flow Rate ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Square Channel ◽  
Wind Generator ◽  
Numerical Predictions ◽  
Wide Range ◽  
Flow Transport ◽  
Corona Wind

Electrohydrodynamically induced flows have shown great potential for many engineering applications. Previous studies have revealed that a corona wind generator can be used to enhance flow transport in a channel. In this study, a corona wind generator with emitting wire electrodes flush mounted on the channel walls is considered for a wide range of operating conditions. Specifically, three configurations of the generator (with 4, 12, and 28 pins of emitting electrodes) are evaluated for their effectiveness in delivering the air flow. To investigate the flow characteristics inside a square channel, three-dimensional governing equations for electric and flow fields are numerically solved. The corona current is first measured experimentally and used in the numerical calculations. Numerical predictions on the velocity profile of corona-induced air flows as well as the volume flow rate delivered have been successfully verified by experimental results.

Influence of free convection on the diffusion current to a sphere in a laminar forced flow regime

1985 ◽  
Vol 50 (12) ◽  
pp. 2697-2714
Author(s):  
Arnošt Kimla ◽  
Jiří Míčka
Keyword(s):  
Asymptotic Expansion ◽  
Free Convection ◽  
Boundary Value Problem ◽  
Concentration Gradient ◽  
Empirical Formula ◽  
Convective Diffusion ◽  
Forced Flow ◽  
Diffusion Current ◽  
Wide Range ◽  
Free And Forced Convection

The formulation and solution of a boundary value problem is presented, describing the influence of the free convective diffusion on the forced one to a sphere for a wide range of Rayleigh, Ra, and Peclet, Pe, numbers. It is assumed that both the free and forced convection are oriented in the same sense. Numerical results obtained by the method of finite differences were approximated by an empirical formula based on an analytically derived asymptotic expansion for Pe → ∞. The concentration gradient at the surface and the total diffusion current calculated from the empirical formula agree with those obtained from the numerical solution within the limits of the estimated errors.

scholarly journals Vector boson fusion at multi-TeV muon colliders

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Antonio Costantini ◽  
Federico De Lillo ◽  
Fabio Maltoni ◽  
Luca Mantani ◽  
Olivier Mattelaer ◽  
...  
Keyword(s):  
Cross Sections ◽  
Vector Boson ◽  
High Energy ◽  
New Physics ◽  
Vector Boson Fusion ◽  
Weak Boson ◽  
Wide Range ◽  
Lepton Colliders ◽  
Muon Colliders ◽  
New Phenomena

Abstract High-energy lepton colliders with a centre-of-mass energy in the multi-TeV range are currently considered among the most challenging and far-reaching future accelerator projects. Studies performed so far have mostly focused on the reach for new phenomena in lepton-antilepton annihilation channels. In this work we observe that starting from collider energies of a few TeV, electroweak (EW) vector boson fusion/scattering (VBF) at lepton colliders becomes the dominant production mode for all Standard Model processes relevant to studying the EW sector. In many cases we find that this also holds for new physics. We quantify the size and the growth of VBF cross sections with collider energy for a number of SM and new physics processes. By considering luminosity scenarios achievable at a muon collider, we conclude that such a machine would effectively be a “high-luminosity weak boson collider,” and subsequently offer a wide range of opportunities to precisely measure EW and Higgs couplings as well as discover new particles.

Compact Modeling of Forced Flow in Longitudinal Fin Heat Sinks With Tip Bypass

2003 ◽  
Vol 125 (3) ◽  
pp. 319-324 ◽  
Author(s):  
C. B. Coetzer ◽  
J. A. Visser
Keyword(s):  
Pressure Drop ◽  
Heat Sink ◽  
Heat Sinks ◽  
Compact Model ◽  
Forced Flow ◽  
Compact Modeling ◽  
Transfer Coefficients ◽  
Wide Range ◽  
Laminar And Turbulent Flow ◽  
Improved Accuracy

This paper introduces a compact model to predict the interfin velocity and the resulting pressure drop across a longitudinal fin heat sink with tip bypass. The compact model is based on results obtained from a comprehensive study into the behavior of both laminar and turbulent flow in longitudinal fin heat sinks with tip bypass using CFD analysis. The new compact flow prediction model is critically compared to existing compact models as well as to the results obtained from the CFD simulations. The results indicate that the new compact model shows at least a 4.5% improvement in accuracy predicting the pressure drop over a wide range of heat sink geometries and Reynolds numbers simulated. The improved accuracy in velocity distribution between the fins also increases the accuracy of the calculated heat transfer coefficients applied to the heat sinks.

Experimental Investigation of Subsonic Turbulent Flow Over Single and Double Backward Facing Steps

1962 ◽  
Vol 84 (3) ◽  
pp. 317-325 ◽  
Author(s):  
D. E. Abbott ◽  
S. J. Kline
Keyword(s):  
Experimental Investigation ◽  
Velocity Profile ◽  
Flow Pattern ◽  
Reynolds Numbers ◽  
Area Ratio ◽  
Single Step ◽  
Reattachment Length ◽  
Double Step ◽  
Wide Range ◽  
Geometric Variables

Results are presented for flow patterns over backward facing steps covering a wide range of geometric variables. Velocity profile measurements are given for both single and double steps. The stall region is shown to consist of a complex pattern involving three distinct regions. The double step contains an assymmetry for large expansions, but approaches the single-step configuration with symmetric stall regions for small values of area ratio. No effect on flow pattern or reattachment length is found for a wide range of Reynolds numbers and turbulence intensities, provided the flow is fully turbulent before the step.

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