• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.16-22
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• 2008

The effect of two-phase spray injected into subsonic cross-flow was studied experimentally. External-mixing of two-phase spray from orifice nozzle with L/d of 3 was tested with various air-liquid ratio that ranges from 0 to 59.4%. Trajectory of spray and breakup phenomena were investigated by shadowgraph photography. Detailed spray structure was characterized in terms of SMD, droplet velocity, and volume flux using PDPA. Experimental results indicate that penetration length was increased and collision point of liquid jets approached to nozzle exit and distributions of mist-like spray were obtained by increasing air-liquid ratio.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.106-109
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• 2007

The spray plume characteristics of liquid water jet injected into subsonic cross-flow at 42 m/s were experimentally investigated. Nozzle has a 1.0 m diameter and L/D=5. Droplet sizes, velocities, volume flux were measured at each downstream area of the injector exit using phase Doppler particle anemometry. Measuring probe position is moved with 3-way transversing machine. Experimental results indicate that SMD is varied from 75 to $120{\mu}m$ distribution and it is uncertain layer structure. SMD peaks at the top of the spray plume. This phenomenon is related to the momentum exchange between column waves and cross-flow stream. Droplet vector velocities were varied from 11.5 to 33 m/s. A higher-velocity region can be identified in down edge region at Z/D : 40, 70 and 100. Lower-velocity region were observed on bottom position of the spray plume. Volume flux is a criterion to the droplet concentration. All volume flux distribution has a same structure that continuously decreases from the center region to the edge of the plume. Z/D : 20 is spatially less concentrated than in Z/D : 100.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.6
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• pp.41-47
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• 2009

This paper presents the spray characteristics of the simplex fuel nozzle with different working fluids for the gas turbine engine. Spray characteristics can be changed with viscosity, surface tension and density. In this research, water and test fluid type 2 which has similar characteristics of the kerosene are used as a working fluid. Spray visualization was performed by using ND-Yag laser and droplet size was measured by using PDPA(Phase doppler particle analyzer) system. The test results show that spray shapes and SMD distributions of two working fluids are similar at main spray region.

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.8-15
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• 1998

The spray characteristics of emulsified fuel of W/O type has been experimentally investigated. The mixture of light oil and water by using ultrasonic energy adding system is used as the emulsified fuel. The SMD of sprayed droplet of emulsified fuel is measured by using the particle size analyzer. Major parameters of the present experimental study are the volume fraction of water in emulsified fuel, $0\sim30%$ by 5%, injection pressure, $10kg_f/cm^2\sim18kg_f/cm^2$ by $2kg_f/cm^2$, and the measurement distance, $10\sim100mm$, between injection nozzle tip and analyzer beam. Compared with light oil, the SMD of emulsified fuel is larger gradually by increasing the volume fraction of water in emulsified fuel, heightening injection pressure and increasing the spray distance. Also, In considering the fact that the pattern of drop size distribution of emulsified fuel is alike that of light oil, the real time spray in coincidence with making emulsified fuel by adding ultrasonic energy can stabilize spray pattern without modificating the injection system used by now.

• International Journal of Automotive Technology
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• v.4 no.3
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• pp.119-124
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• 2003

Dimethyl Ether (DME) is an excellent alternative fuel that provides lower particulate matter (PM) than diesel fuel under the same engine operating conditions. Spray characteristical of DME in common rail injection system were investigated within a constant volume chamber by using the particle motion analysis system. The injector used in this study has a single hole with the different orifice diameter of 0.2, 0.3 and 0.4 mm. The injection pressure was fixed at 35MPa and the ambient pressure was varied from 0.6 to 1.5 MPa. Spray characteristics such as spray angle, spray tip penetration and SMD (Sauter mean diameter) were measured. Spray angle was measured at 30d$_{0}$, downstream of the nozzle tip. The measured spray angie increased with increase in the ambient pressure. Increase of the ambient pressure results in a decrease of spray penetration. The experimental result, of spray penetration were compared with the predicted one by theoretical and empirical models. Increase in the ambient pressure and nozzle diameter results in an increase of SMD at a distance 30, 45 and 60d$_{0}$, downstream of the nozzle, respectively.ely.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.255-259
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• 2008

This paper presents the spray characteristics of the oxidizer rich preburner injector which can be used in the high-thrust rocket system. We designed the basic shape of the liquid-liquid coaxial swirl injector for the rocket oxidizer rich preburner injection system. To understand the spray angle variation with the high pressure environment, the spray visualization in the high pressure chamber was preformed. Also we measured the droplet velocity, the Sauter Mean Diameter(SMD), the volume flux and the number density with the PDPA system by using water in atmospheric pressure. The results show that the spray angle is reduced by increasing ambient pressure and maximum droplet velocity is shown from a nozzle tip and then the droplet velocity decreases as a spray moves to the downstream. The SMD decreases on the axial distance from 20 mm to 50 mm but it increases over 50 mm. That is due to the increasing number of collision with each droplet and interaction with ambient air on going downstream direction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.175-178
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• 2008

Spray characteristics for the simplex atomizer are investigated. The atomizer was tested with kerosene which is generally used as a fuel for gas turbine engines. But it is very difficult and dangerous to measure spray performance. So water is used as a working fluid for measuring the droplet information. In this study, spray visualization was performed by using ND-Yag Laser and droplet size was measured by using PDPA system by using two different working fluid such as water and test fluid # 2 which has similar characteristics of the kerosene. The test results show that SMD of water bigger than test fluid # 2 about 5$\sim$15 mm because surface tension of water is higher by a factor of 3. But the spray angles and the spray shapes have similarity

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.40-47
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• 2010

This study deals with the investigation about the effect of the pilot and split injection strategies on the spray-atomization characteristics of biodiesel fuel derived from a soybean oil. Experimental results were compared with the calculation results obtained from the numerical analysis. Fuel properties of biodiesel according to the variation of the fuel temperature were inserted to the fuel library in the KIVA code. The amount of fuel injection is divided into equal mass for each split and main injection. In this work, the pilot injection strategy can be achieved by the amount of fuel injection shortly before the start of the main injection. A spray tip penetration, radial distance and spray area were measured for the analysis of macroscopic spray characteristics. In addition, the local and overall droplet size distribution were calculated by using KIVA-3V code to study the effect of split and pilot injection on the atomization performance under high ambient pressure. From these studies, the experimental results showed the multiple injection induced the decrease of the spray tip penetration due to the reduction and division of the spray momentum compared to single injection. In the atomization performance, the droplet size increased in the case of the multiple injection a little. Moreover, the SMD slightly increased as the fuel droplets goes through the axial direction. The spray behavior of numerical results were well predicted the experimental multiple spray characteristics of biodiesel fuel.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.510-519
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• 2013

In this study, the spray characteristics of a pressure swirl atomizer classified into a liquid sheet-type swirl nozzle for Urea-SCR system were investigated experimentally with the variation of injection pressure. The length to diameter ratio ($l_o/d$) of the nozzle was 3.1, and the swirler was set inside the nozzle tip to give injecting fluid angular momentum. The injection duration of the nozzle was controlled by PWM (pulse width modulation) modes. The development processes of the spray were imaged by a 2-D PIV system, and the change of spray angle was measured. The atomization characteristics, including axial velocity and SMD, were measured using a 2-D PDA system with the injection pressures at room temperature and ambient pressure conditions. As the experimental results, the injection pressure had a significant impact on the spray structure showing a different shape around the spray leading edge, and the smaller SMD was observed with increasing injection pressures, which was similar to that of the previous work.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.447-454
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• 2017

A three-dimensional two-phase large eddy simulation(LES) has been conducted to investigate the breakup and atomization of liquid jets such as a diesel jet in parallel flow and water jet in cross flow. Gas-liquid two-phase flow was solved by a combined model of Eulerian for gas flow and Lagrangian for a liquid jet. Two stochastic breakup models were implemented to simulate the liquid column and droplet breakup process. The penetration depth and SMD(Sauter Mean Diameter) were analyzed, which was comparable with the experimental data.