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.

Performance of a Multiple Stage EHD Gas Pump in a Square Channel

2011 ◽  
Author(s):  
A. K. M. Monayem H. Mazumder ◽  
F. C. Lai
Keyword(s):  
Maximum Velocity ◽  
Gas Flows ◽  
Maximum Performance ◽  
Pump Performance ◽  
Square Channel ◽  
Wide Range ◽  
Cooling Fans ◽  
Conventional Cooling ◽  
Two Stages ◽  
Better Than

Earlier studies have shown that an electric field in the form of corona discharge can effectively produce air flow. Using this technique, it has been demonstrated that an electrohydrodynamic (EHD) gas pump can produce 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. In this study, an EHD pump with two stages, each stage with 28 emitting electrodes, 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. To seek the relation between the pump performance and number of stages, the EHD gas pump is critically evaluated by experimental measurements and numerical simulations. The maximum performance of 34 L/s/W is achieved by using a total of 56 electrodes with 0.5 inch wide grounded plate in each stage.

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.

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 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.

Research of the activity and viability of spermatozoa at different concentrations and proportions of diluents after incubation

2020 ◽  
pp. 88-95
Author(s):  
Svitlana Lobchenko ◽  
Tetiana Husar ◽  
Viktor Lobchenko
Keyword(s):  
Plasma Concentration ◽  
Incubation Time ◽  
Coefficient Of Variation ◽  
Incubation Medium ◽  
Wide Range ◽  
Series Of Experiments ◽  
The Subject ◽  
Boar Spermatozoa ◽  
Native Plasma ◽  
Better Than

The results of studies of the viability of spermatozoa with different incubation time at different concentrations and using different diluents are highlighted in the article. (Un) concentrated spermatozoa were diluented: 1) with their native plasma; 2) medium 199; 3) a mixture of equal volumes of plasma and medium 199. The experiment was designed to generate experimental samples with spermatozoa concentrations prepared according to the method, namely: 0.2; 0.1; 0.05; 0.025 billion / ml. The sperm was evaluated after 2, 4, 6 and 8 hours. The perspective of such a study is significant and makes it possible to research various aspects of the subject in a wide range. In this regard, a series of experiments were conducted in this area. The data obtained are statistically processed and allow us to highlight the results that relate to each stage of the study. In particular, in this article it was found out some regularities between the viability of sperm, the type of diluent and the rate of rarefaction, as evidenced by the data presented in the tables. As a result of sperm incubation, the viability of spermatozoa remains at least the highest trend when sperm are diluted to a concentration of 0.1 billion / ml, regardless of the type of diluent used. To maintain the viability of sperm using this concentration of medium 199 is not better than its native plasma, and its mixture with an equal volume of plasma through any length of time incubation of such sperm. Most often it is at this concentration of sperm that their viability is characterized by the lowest coefficient of variation, regardless of the type of diluent used, which may indicate the greatest stability of the result under these conditions. The viability of spermatozoa with a concentration of 0.1 billion / ml is statistically significantly reduced only after 6 or even 8 hours of incubation. If the sperm are incubated for only 2 hours, regardless of the type of diluent used, the sperm concentrations tested do not affect the viability of the sperm. Key words: boar, spermatozoa, sperm plasma, concentration, incubation, medium 199, activity, viability, rarefaction.

Effect of Contact Ratio on Spur Gear Dynamic Load With No Tooth Profile Modifications

1996 ◽  
Vol 118 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Chuen-Huei Liou ◽  
Hsiang Hsi Lin ◽  
F. B. Oswald ◽  
D. P. Townsend
Keyword(s):  
Dynamic Load ◽  
Spur Gear ◽  
Tooth Size ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Wide Range ◽  
Gear Contact ◽  
Center Distance ◽  
Selection Of ◽  
Better Than

This paper presents a computer simulation showing how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented in this paper was performed by using the NASA gear dynamics code DANST. In the analysis, the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds, a contact ratio close to 2.0 minimized dynamic load. For low-contact-ratio gears (contact ratio less than two), increasing the contact ratio reduced gear dynamic load. For high-contact-ratio gears (contact ratio equal to or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high-contact-ratio gears minimized dynamic load better than low-contact-ratio gears.

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