• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2032-2041
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• 2004

Results from an experimental study of flow distribution in a close-coupled catalytic converter(CCC) are presented. The experiments were carried out with a flow measurement system specially designed for this study under steady and transient flow conditions. A pitot tube was a tool for measuring flow distribution at the exit of the first monolith. The flow distribution of the CCC was also measured by LDV system and flow visualization. Results from numerical analysis are also presented. Experimental results showed that the flow uniformity index decreases as flow Reynolds number increases. In steady flow conditions, the flow through each exhaust pipe made some flow concentrations on a specific region of the CCC inlet. The transient test results showed that the flow through each exhaust pipe in the engine firing order, interacted with each other to ensure that the flow distribution was uniform. The results of numerical analysis were qualitatively accepted with experimental results. They supported and helped explain the flow in the entry region of CCC.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.2
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• pp.77-87
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• 2000

The water entry forces acting on an air-dropped torpedo are of the restrictions on launch speed and launch altitude, because it could cause the structural damage to components of torpedo. Therefore, it is necessary to estimate the water entry forces with confidence according to launch conditions. In this study, an approximation method for water entry forces is presented, and the results using this approximation are compared with those of other numerical methods. The magnitude and duration of impact forces estimated by the present approximation agree with those of impact by the analysis of ideal or viscous flow. This method can give useful tools to select the launch in initial design stage.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.401-404
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• 2008

Pressurization system in a liquid-propellant launcher supplies the controlled gas into the ullage volume of propellant tanks to feed propellants to combustion chamber by pressurizing propellants stored in propellant tanks. The ullage part of propellant tank should be constantly pressurized to supply the propellants stored in propellant tanks to turbo-pump or combustion chamber by pressurant pressurization system. Pressurant used to pressurize propellants is generally stored in a series of tanks at cryogenic temperature and high preassure inside an oxidizer tank. The reason is to store the quantity of pressurant as much as possible and to make pressurant tanks as small as (i.e. as light as) possible. However for test convenience pressurant tank is located at STP (standard temperature and pressure) environment in this study. Orifices are widely adapted to several pressurization systems in liquid rocket propulsion systems. Discharge coefficients of orifices are essentially needed for the optimized design of pressurization system in liquid rocket propulsion system. For this study gaseous nitrogen was served as pressurant and rounded entry orifices were employed. The forty-two (42) rounded entry orifices (the radii of curvatures are 0.5 and 1.0) have been tested experimentally in the supersonic flow region. The discharge coefficients of rounded entry orifices with inside diameters ranging from about 1.4 to 5.0mm was measured with 0.95 ${\sim}$ 0.99.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.483-488
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• 2009

When a train enters into the tunnel with high speed, a compression wave generated inside the tunnel has been studied as a one-dimensional phenomenon. However, one-dimensional approach can't analyze 3-dimensional flow effect in the vicinity of the train body. In this research, so as to overcome this weak point, a prediction method of the wavefront of a compression wave using steady state solution has been used for the parametric study considering 3-dimensional effects of the interactions between trains and tunnels. The effective hood shapes were deduced in both cases of the train's entry into the tunnel on the single track and on a side of the double track. As a result, in case of the train's entry on a side of the double track, the increase of compression wave value propagated to the tunnel inside have appeared compared with the train's entry on the single track. Also, a horizontally convex elliptic hood shape is more effective at the train's entry on a side of the double track for the purpose of a decrease of wavefront gradient of a compression wave.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.559-564
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• 2001

Advanced gas turbine engines employ turbine entry temperatures so high that cooling of the turbine blades is essential. The coolant flow introduces losses which need to be minimized, and therefore it is important that the minimum amount of coolant is used. This work presents the result of the one-dimensional analysis and the effect of the boundary conditions on coolant flow rate in gas turbine blades.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.9
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• pp.888-894
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• 2001

Advanced gas turbine engines employ turbine entry temperatures so high that cooling of the turbine blades is essential. The coolant flow introduces losses which need to be minimized, and therefore it is important that the minimum amount of coolant should be used. This work presents the result of the one-dimensional analysis and the effect of the boundary conditions on coolant flow rate in gas turbine blades.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.879-887
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• 2003

The flow in a parallel walled test channel, when obstructed with a geometry at the entrance, can be forward, reverse and stagnant depending on the position of the obstruction. This interesting flow phenomenon has potential benefit in the control of energy and various flows in the process industry In this experiment, the flat plate obstruction geometry was used as an obstruction at the entry of the test channel. The parameters that influence the flow inside and around the test channel were the gap (g) between the test channel and the obstruction geometry, the length (L) of the test channel and the Reynolds number (Re). The effect of the gap to channel width ratio (g/w) on the magnitude of the velocity ratio (V$\_$i/ / V$\_$o/ : velocity inside/ velocity outside the test channel) was investigated for a range of Reynolds numbers. The maximum reverse flow observed was nearly 20% to 60% of the outside velocity for Reynolds number ranging from 1000 to 9000 at g/w ratio of 1.5. The maximum forward velocity inside the test channel was found 80% of the outside velocity at higher g/w ratio of 8. The effect of the test channel length on the velocity ratio was investigated for different g/w ratios and a fixed Reynolds number of 4000. The influence of the Reynolds number on the velocity ratio is also discussed and presented for different gap to width ratio (g/w). The flow visualisation photographs showing fluid motion inside and around the test channel are also presented and discussed.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.128-133
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• 2012

This research has analyzed factors affecting customers' satisfaction when they use parking lots of big retailers so that, in case of constructing, operating or managing such retailers, proper measures can be come up with. The analysis has been implemented on the basis of survey, and influence factors including entry/exit lamp, parking cars' traffic flow, parking type, pedestrians' movement after parking and safety. Parking lot users' satisfaction has been analyzed by using the Structural Equation Modelling and, as a result of it, in case of a detached or single building, pedestrians' movement flow after parking contributed the most to the users' satisfaction, while, in case of multipurpose complex, parking cars' traffic flow has the most influential factor. It is interpreted that users of a single building put a bigger emphasis on entry to the shop and their way back to the parked area after their shopping while customers of multipurpose complex might have various purposes of visiting the place and there are relatively more cars so that they put more emphasis on traffic counterflow, other cars and pedestrians.

• Journal of computational fluids engineering
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• v.21 no.3
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• pp.55-63
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• 2016

Nowadays, large container ships are continually developed and that's why the bow and stern structural stability problems by slamming become a significant more and more. However, due to the complexity of slamming, it is difficult to consider those problems at the design stage. For this reason, we attempt numerical analysis through SNUFOAM by generating the bow and stern two-dimensional cross-sectional grid in WILS JIP experiment at KRISO. Unlike the conventional method for the computation time saving, by setting the inlet flow conditions referred to the model test, we analyzed the slamming without applying the grid deformation method. As a result, when the stern model, as in the previous studies, it was possible to obtain quantitatively the fluid impulse is close to the experimental results. When the bow model, we can found the change by the position of force sensors which are derived for the bulbous bow and obtained fluid impulse and flow shape at slamming similar to the model test.

• Journal of ILASS-Korea
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• v.9 no.1
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• pp.21-29
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• 2004

The flow characteristics of a swirl injector were investigated with the variation of the flow condition and geometric dimensions, such as orifice length for considering the viscous effect and tangential entry port area for considering the swirl intensity. The liquid film thickness strongly influencing on the formed drop size of the spray was measured using a new technique. The film thickness measurement technique proposed here, used the attenuation of fluorescence signal near the injector exit. The breakup length that is important for the flame location as well as the spray cone angle which influences on the ignition performance was measured using a backlit stroboscopic photography technique. From the experimental results, it is found that an increase in injection pressure decreased the film thickness and breakup length, and also enlarged the spray cone angle. A decrease in orifice length and tangential entry port area has a similar tendency of thinner film thickness, shorter breakup length and larger spray cone angle. In the present study, we proposed empirical models of the flow characteristics of the swirl injectors.