• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.2
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• pp.37-48
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• 1991

This paper shows the characteristics of sparkover discharge in flowing air ranging from O(Reynolds number, Re) to $10.52{\times}10^4$(Re). Also, we investigated changes of discharge pattern for constant input power by adjustment of the Reynolds number. Flowing air duct of this investigation is a circular tube. The flow at the experimented positions' section is described as fully development laminar flow. The important results obtained from this study are as follows. The sparkover discharge path of flowing air can be analyzed by the theories of flow field for air. The sparkover voltage shows nearly the maximum value when the Reynolds number of flowing air ranges $3{\times}10^4$ to $4{\times}10^4$The maximum sparkover voltages of flowing air are about 6.3[kV] higher than those of static air. The discharge pattern can be controlled by adjustment of the Reynolds number.

• Korean Journal of Optics and Photonics
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• v.5 no.4
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• pp.461-465
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• 1994

The spatial flatness of dye jet depending on the Reynold's number has analyzed by using a Michelson interferometer. When the Reynold's number of dye jet was 600, the flatness of the flow was the best. Under this condition, the dye laser with Littman-type configuration has been operated in a single longitudinal mode at the pumping energy of 0.5~1.0 mJ/pulse. The conversion efficiency and beam divergence were 4.7% and 3 mrad, respectively. ively.

• Steel and Composite Structures
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• v.42 no.3
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• pp.389-396
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• 2022

This investigation in fluid mechanics surrounds around the variety of flow problems for different fluids along the stretching cylinder. Numerical procedure is carried out for the obtained resultant equations by Keller-Box technique. Numerical study of laminar, steady, viscous and incompressible two dimensional boundary layer flow of effects of suction and blowing on boundary layer slip flow of Casson fluid along permeable exponentially stretching cylinder has been carried out in the present draft. physical parameters i.e., Nusselt number and skin friction coefficient, suction parameter and the local Reynold number are investigated on velocity profile and elaborated through proper graphs and table.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.6
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• pp.569-577
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• 2009

As the scale factor of model propellers utilized in cavitation test is about 40, it is difficult to find out practical countermeasures against the small area erosions on the blade tip region throughout model erosion tests. In this study, a partial propeller blade model was used for the observation of cavitation pattern for the eroded propeller. A partial propeller blade model was manufactured from 0.7R to tip with expanded profile and with adjustable device of angle of attack. Reynold's number of a partial propeller blade model is 7 times larger than that of a model propeller. Also, anti-singing edge and application of countermeasures to partial propeller blade model which produced in large scale can be more practical than a model propeller. For the observation of cavitation at high Reynold's number, high speed cavitation tunnel was used. To find out the most severe erosive blade position during a revolution, cavitation observation tests were carried out at 5 blade angle positions.

• Advances in nano research
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• v.10 no.3
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• pp.263-270
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• 2021

The present manuscript focuses the effects of suction on the flow of the dusty fluid along permeable exponentially stretching cylinder. Derived PDEs for this work are changed into ODEs by adopting right transformations. Numerical procedure is carried out for the obtained resultant equations by Shooting Technique in accordance with Runge-Kutta (RK-6) technique. Obtained results for the parameters namely, particle interaction parameter, suction parameter and Reynold number parameters are probed thoroughly. Some salient points are: (a) Fluid velocity decreases and the dust phase velocity rises for the higher values of particle interaction parameter; (b) more suction produces retarding velocities for both the phases; (c) high Reynold number slows down the fluid velocity while the speed of dust phase and (d) skin friction coefficient goes high for all these parameters.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.1-6
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• 2008

The output of the Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide basic data for the design of regenerator matrix, characteristics of flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, two different wire screens were used. The results are summarized as follows; 1. With the wire screen of No. 50 as regenerator matrices, pressure drop of working fluid of the oscillating flow is shown as 3 times higher than that of one directional flow, not too much influenced by the number of packed meshes. 2. With the wire screen of No. 100 as regenerator matrices, pressure drop of working fluid of the oscillating flow is shown as 2.5 times on the average higher than that of one directional flow, not too much influenced by the number of packed meshes. 3. Under one directional flow which used regenerator matrices with both 200, 240, and 280 wire screens of No. 50 and 320, 370, and 420 wire screens of No. 100, the relationship between the friction factor and Reynold No. is shown as the following formula. $$f=\frac{0.00326639}{Re\iota}-1.29106{\times}10^{-4}$$ 4. Under oscillating flow which used regenerator matrices with both 200, 240, and 280 wire screens of No. 50 and 320, 370, and 420 wire screens of No. 100, the relationship between the friction factor and Reynold No. is shown as the following formula. $$f_r=\frac{0.000918567}{Re\iota}+1.86101{\times}10^{-5}$$ 5. The pressure drop is shown as high in proportion as the number of meshes has been higher, and the number of packed wire screens as matrices increases.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.669-678
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• 1994

The BOD removal characteristics of submerged biofilters filled with three kinds of filter media respectively were experimentally examined with constant temperature, pH value and variable BOD loading and recirculation ratio. Obtained results are as follows; 1. The BOD removal ratio decreases with the increasing $BOD_5$ volumetric loading rate, and the loading rate for the BOD removal over 90% is lower thean $1.6kg{\cdot}BOD_5/m^3{\cdot}d$ for the plastic media of Netring and cubic wire meshes. This is a much large value than $0.3{\sim}0.8kg{\cdot}BOD_5/m^3{\cdot}d$ for conventional activated sludge process. The required submerged biofilter volume is found to be much samller than that of conventional activated sludge process. 2. The decreasing order of BOD removal is Netring (random plastic media), cubic wire meshes (plastic module), and then gravel (stone media). This is mainly due to the media characteristics such as void ratio, specific surface area and media shapes. 3. The $BOD_5$ removal rate increases with the recircuration ration, but the rate of increases becomes samaller as the recirculation ratio increases over 20. When $BOD_5$ loading is $1.8kg{\cdot}BOD_5/m^3{\cdot}d$, the required recirculation rationto obtain 90% $BOD_5$ removal is about 20 for Netring and it was about 30 for cubic wire meshes. 4. Reynold's Number increases with recirculation ratio, and the Reynold's Numbers corresponding to the recircuration ratio of 10~50 are less than 52, showing laminar up flows in the filter. The settled and effluent sludges increase with increase of Reynol's Number, and there are the definite Reynold's Numbers at which the settling sludge concentrations become nearly constant respectively in each filters. 5. In this submerged biofilter system, small volume of sludge hopper can be substituted for a separated settling tank.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.267-279
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• 2003

The present investigation deals with the application of Adomian's decomposition method to blood flow through a constricted artery in the presence of an external transverse magnetic field which is applied uniformly. The blood flowing through the tube is assumed to be Newtonian in character. The expressions for the two-term approximation to the solution of stream function, axial velocity component and wall shear stress are obtained in this analysis. The numerical solutions of the wall shear stress for different values of Reynold number and Hartmann number are shown graphically. The solution of this theoretical result for a particular Hart-mann number is compared with the integral method solution of Morgan and Young［17］.

• Advances in nano research
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• v.10 no.4
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• pp.349-357
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• 2021

In present study, the numerical investigations are carried out for effects of suction and blowing on boundary layer slip flow of casson nano fluid along permeable stretching cylinder in an exponential manner. The modeled PDEs are changed into nonlinear ODEs through appropriate nonlinear transformations. Change in physical quantities like friction coefficient, Nusselt and Sherwood numbers with variation of the aforementioned parameters are also examined and their numerical values are listed in the form of tables. Effects of Reynold number, suction parameter, Prandtl number, Lewis number, Brownian motion parameter and thermophoresis parameter are seen graphically with temperature profile.

• Journal of Power System Engineering
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• v.10 no.3
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• pp.17-22
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• 2006

Surface modifications like rib-roughening and displaced insert devices like the twisted tape are commonly used in applications such as compact heat exchangers and cooling systems. In this paper, regionally averaged heat transfer distributions in square channels with twisted tape inserts and with twisted tape inserts plus interrupted ribs are respectively investigated. The square ribs are arranged to follow the trace of the twisted tape and along the flow direction defined as axial interrupted ribs. Each wall of the square channel is composed of isolated aluminum sections. Regionally averaged Nusselt number and channel averaged Nusselt number in turbulent air flows are presented for Reynold numbers from 8,900 to 29,000. We have obtained the following conclusions from the experimental study: 1) The local Nusselt number in the two-sided heated case is higher than that in the four-sided heated condition. 2) In the 4 heating wall channel with twisted tape inserts, Nusselt number based on bottom wall temperature is enhanced by 1.2 - 1.6 times if adding the axial interrupted ribs on the bottom wall only. 3) The twisted tape with interrupted ribs under the two-sided heating condition produces the highest heat transfer coefficient.