• Proceedings of the KSME Conference
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• 2001.06e
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• pp.777-782
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• 2001

In this study, we used In-line orifice mixer for efficient chemicals mixing in water treatment. The method of using In-line orifice mixer has been already proved the improvement of water treatment efficiency. Numerical study was performed using FLUENT, a commercial code, to standard design and production of effective In-line orifice mixer. As variable for exactly standardizing, a proper ratio between an outer diameter of cone and a diameter of pipe, a distance between cone and orifice, a determination of orifice diameter for an optimal mixing, a distance between injection nozzle's position and cone, Numerical study has been performed for optimal standard and analyzed flow field on a basis of turbulent intensity in an orifice downstream.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.288-293
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• 2001

This paper presents the water-hammer effect due to the rapid opening and closing of isolation valve and thruster valve in the spacecraft propulsion system. The single propellant feed system was modeled to investigate the maximum peak pressure due to the water-hammer effect. The test parameters are tank supply pressure, shape and throat length of orifice and line length. Kerosene was used as the inert simulant propellant liquid instead of hydrazine. As downstream line length after isolation valve increased from 1.5 to 2.5m, the maximum line-filling water-hammer peak pressure decreased, but the average time interval between peak pressures increased. The maximum line-filling water-hammer peak pressure with orifice was lower than without orifice, and the maximum line-filling water-hammer peak pressure with orifice at the back of isolation valve was lower than with orifice in front of isolation valve. Without orifice, the maximum water-hammer peak pressure due to the rapid opening and closing of the thruster valve was about 126% of tank supply pressure. With orifice, it decreased. As orifice throat length increased, it decreased. The maximum water-hammer peak pressure due to the rapid closing of the thruster valve with converging-diverging orifice was lower than normal orifice. It was found that the orifice as a means of pressure drop was very effective to reduce the water hammer peak pressure at the thruster valve. The results of this study can be used for the design of spacecraft liquid propulsion feed system.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.451-455
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• 2010

In this study, the various supply system of LRE such as a feed-line, an elbow, and an orifice as a part of integrated analyzing has been combined to develop the performance analysis program. Computational analysis has been used to compare the results and to verify the validity and limitation conditions of the performance analysis program by changing orifice positions.

• 한국전산유체공학회:학술대회논문집
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• 2001.10a
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• pp.132-137
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• 2001

We used In-line orifice mixer for efficient chemicals mixing in water treatment. The method of using In-line orifice mixer has been already proved the improvement of water treatment efficiency. Code of computational fluid dynamics for numerical analysis was performed using FLUENT, a commercial code. As variable for exactly standardizing, a proper ratio between an outer diameter of deflector and a diameter of pipe, the distance between deflector and orifice, a determination of orifice diameter fur an optimal mixing, a distance between injection nozzle's position and cone, Numerical study has been performed for optimal standard and analyzed flow field on a basis of turbulent intensity in an orifice downstream.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.11-16
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• 2006

Effects of an orifice on suppression of pressure oscillation in a fluid feeding line are investigated numerically through the installation of an orifice inside the feeding line. Based on linear acoustic theory, acoustic-damping effect of an orifice is emphasized in this study. When an orifice is installed at the node of pressure oscillation corresponding to the anti-node of velocity oscillation, damping capacity is maximized. On the other hand, the orifice installed at the anti-node of pressure oscillation has little damping capacity. As the blockage ratio and thickness of an orifice increase in the feeding line, damping factor increases. The feeding line with smaller diameter has more damping capacity, but damping factor increases more appreciably with blockage ratio in the feeding line with larger diameter.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.689-696
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• 2008

In a water treatment process a complete and homogeneous dispersion of the coagulants in the raw water could be most important factor. This research was performed to evaluate coagulation performance of the in-line-orifice mixer which was recently introduced as a rapid mixing device. The test was to determine the actual coagulant dispersion distribution on the overall cross-section at a distance of 1.6~3D from the chemical injection point by measuring zeta potential. From the results of zeta potential test, it was shown that the coagulant dispersion within the in-line orifice mixer was occurred very unevenly. The results have confirmed that it is necessary to increase the velocity of coagulants injection or pressurized water rates, in order to reduce nonuniform distribution of chemicals.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.313-317
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• 2009

The orifice in the propellent feeding pipe line of a Liquid Rocket Engine(LRE) is used to balance the pressure of the pipe line. When a LRE starts up, pressure at the upstream of the orifice rapidly increases. In this case, pressure waves occuring by resistance of the orifice may induce low frequency instability in the pipe line. For this reason the study of dynamic characteristics of orifices is needed to prevent the instability. A pump is used to build up the pressure, and the pressure is measured upstream and downstream of the orifice when the orifice diameter is changed. With the increase of orifice diameter, water hammer decreases, but the effect of resistance downstream is increases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.359-362
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• 2009

Damping characteristics of pressure oscillation induced by an orifice in fluid feeding line for are investigated numerically and experimentally. Assuming small pressure oscillation, acoustic damping effect of orifice is confirmed experimentally, and with the mean flow, damping characteristics of an orifice are investigated numerically. When an orifice is installed at the node of pressure oscillation corresponding to the anti-node of velocity oscillation, suppression of pressure oscillation is maximized and with the mean flow, the resonant frequency is decreased. And, it is found that the optimal position of an orifice for damping shouled be changed.

• Journal of computational fluids engineering
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• v.7 no.2
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• pp.1-7
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• 2002

The present study is developed device that effectively mixes raw water and chemicals by using the residual head of fluid in the front pipe of flocculation basin, and performed non-dimensional analysis and presented design standard to apply to water plants that have different equipment capacity. The variables for design are a proper ratio between an outer diameter of deflector and a diameter of pipe, a distance between deflector and orifice and a determination of orifice diameter for an optimal mixing. Numerical study has analyzed flow field on a basis of turbulent intensity in an orifice downstream. As Reynolds number of In-Line Orifice was increased from identical design variable, the turbulent intensity of pipe center was no changed almost.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.202-206
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• 2009

We studied the spray characteristics of the high-speed rotating fuel injection system. The diameter of in-line injection orifices are varied from 1mm to 5mm and the number of in-line injection orifices are varied from 3 to 12. Droplet size, velocity and spray distribution were measured by the PDPA(Phase Doppler Particle Analyzer) system and spray was visualized. From the test results, the liquid column generated from the injection orifice is mainly controlled by the rotational speeds. Also diameter of injection orifices and number of injection orifices have influence on the diameters of droplet. Consequently, we find out that the basic mechanism of controlling the droplet size is the liquid film thickness in the injection orifice.