• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.146-153
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• 1997

An experiment was conducted to figure out the atomization characteristics of a highly viscous biodiesel fuel with rice-barn oil applying and ultrasonic energy into it. A spray simulator for the droplet atomization, an ultrasonic system, and six different nozzles(3 pintle-type nozzles and 3 single hole-type nozzles) were made. To investigate effects of ultrasonic energy in a highly viscous liquid fuel, an immersion liquid method was used as a measurement method on droplet size distributions. It was found that the ultrasonic energy was effective for the atomization improvement of the rice-bran oil as a highly viscous biodiesel fuel and the factor나 such as the nozzle opening pressure, pin-edge angles, hole diameters, and collection distances affected the atomization of spray droplets.

• Journal of ILASS-Korea
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• v.4 no.1
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• pp.45-54
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• 1999

The spray characteristics of a direct injection multi-hole diesel nozzle having the 2-spring nozzle holder were investigated by using the image processing system and a PDPA(phase Bowler particle analyzer) system. The spray tip penetration, the spray angle, and the droplet diameter and velocity with the variation of the pump speed, injection quantity were measured. From, the experiments, we know that there are small droplets which are not to be detected with spray image around the leading edge of the spray. In order to represent the mean characteristics of the intermittent spray very well, it is very important to set the time windows accurately. From the measurements along the axis of the spray, close to the nozzle, the initially injected droplets are overtaken by droplets that follow them. And also there are the maximum axial mean velocity and SMD at the following part of the leading edge of the spray.

• International Journal of Automotive Technology
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• v.5 no.1
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• pp.9-16
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• 2004

An experimental study was carried out to characterize the spray atomization process of micro-machined port fuel injectors with a piezoelectric atomization device, which can generate pressure pulsations through vibration of a piezoelectric transducer. In this study, several types of micro-machined arrays such as 30∼200-microns of hole arrays were tested. Both a dual-stream and a central-port injectors with micro-machined arrays were tested and compared with normal port fuel injectors. The spray visualization was conducted to characterize overall spray structure and phase Doppler particle analyzer (PDPA) system was used to quantify the droplet size and velocity. In addition, the pressure history was recorded by using digitized signal from pressure transducer. The results showed that modulation is effective to the spray atomization for tested injectors and atomization performance depends on injector design factors, orifice sizes, and frequency and power of the modulator. A number of resonance frequencies of the modulator was modified by injector parameters and temperature. In addition, our results suggested that design of sufficient space among holes is critical to avoid droplet coalescence in the multi-hole micro-machined injectors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.20-23
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• 2011

The spray and atomization characteristics of swirl coaxial injectors which use gas methane and LOx as propellants are investigated experimentally with a recess length variation. Mass distribution and spray angle are measured by a patternator and droplet size to find atomization characteristics are measured by GSV(Global Size and Velocity) system. As a result, when the liquid sprayed, the spray angle decreased and the atomization characteristic was improved with the recess length increase. When the gas and liquid injected simultaneously, the spray angle was decreased and the atomization characteristic was improved comparing to only the liquid injection.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2053-2065
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• 2003

The current trend in automotive finishing industry is to use more electrostatic rotating bell (ESRB) need space to their higher transfer efficiency. The flow physics related with the transfer efficiency is strongly influenced by operating parameters. In order to improve their high transfer efficiency without compromising the coating quality, a better understanding is necessary to the ESRB application of metallic basecoat painting for the automobile exterior. This paper presents the results from experimental investigation of the ESRB spray to apply water-borne painting. The visualization, the droplet size, and velocity measurements of the spray flow were conducted under the operating conditions such as liquid flow rate, shaping airflow rate, bell rotational speed, and electrostatic voltage setting. The optical techniques used in here were a microscopic and light sheet visualization by a copper vapor laser, and a phase Doppler particle analyzer (PDPA) system. Water was used as paint surrogate for simplicity. The results show that the bell rotating speed is the most important influencing parameter for atomization processes. Liquid flow rate and shaping airflow rate significantly influence the spray structure. Based on the microscopic visualization, the atomization process occurs in ligament breakup mode, which is one of three atomization modes in rotating atomizer. In the spray transport zone, droplets tend to distribute according to size with the larger drops on the outer periphery of spray. In addition, the results of present study provide detailed information on the paint spray structure and transfer processes.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.199-210
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• 1998

The skill that utilizes atomization of the liquid has been widely used in the field of industry and engineering. Though there are dozens of methods to make atomization, the pressure type injection nozzle is frequently used in washing of parts, pastourization and painting because it has relatively simple system. This study is to reveal the characteristics of atomizing formed by three different types of the pressure type injection nozzle. We measured velocity and diameter of droplet to compare and analyze characteristic of each nozzle. In case of velocity, atomization of hollow-cone nozzle is irregular than others and change of radial direction is especially large. Atomization of flat nozzle is nearly uniform. In case of diameter, atomization of hollow-cone nozzle is increased rapidly, as measurement point become more distant from the center of nozzle. Atomization of flat nozzle has the most fixed magnitude. Accordingly, full-cone nozzle can be used irrespective of the form of subject and hollow-cone nozzle is proper to the occasion to spray large and smooth subject. Also, flat nozzle is proper to the occasion to spray a part of subject and long groove.

• Journal of ILASS-Korea
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• v.16 no.4
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• pp.201-209
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• 2011

Optimum engine performance is obtained when the spray characteristics is well matched to the geometry of a combustion chamber. Among many parameters governing the combustion performance in internal combustion engine, fuel supply characteristics and atomization are important performance factors. Therefore, spray characteristics of high pressure multi-hole injector has been studied experimentally. An experimental test system has been made to operate high pressure injection system and to visualize spray behavior. Spray visualization has been performed to analyze spray formation, spray cone angle, bent angle and penetration length. Spray interaction with piston has been analyzed with various injector installation angle, injection pressure and ambient pressure. Test results show that penetration length is greatly influenced by the injection pressure. Penetration length is decreased as ambient pressure increased. Spray cone angle is increased as injection pressure and ambient pressure increased. However, bent angle is not influenced by the change of injection pressure and ambient pressure. Spray cone angle distribution map is plotted using the experimental data. Fuel movement around the spark-plug has been enforced as increasing injector installation angle.

• Journal of ILASS-Korea
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• v.14 no.3
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• pp.97-102
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• 2009

The spray characteristics of the high speed rotating fuel injection system were studied. The five variants of rotating fuel nozzle were used by spray test. The diameter of single column injection orifices are varied from 1 mm, 2 mm, 3 mm, 4 mm and 5 mm. We constructed high speed rotating test rig and measured droplet size by PDPA (Phase Doppler Particle Analyzer) system. Also spray was visualized by using high speed camera. In the test results, we could understand that length of liquid column from the injection orifice is mainly controlled by the rotational speeds. SMD is decreased with increasing injection orifice diameter and rotational speeds. Furthermore, from the comparison to the theoritical calculation, we confirmed that SMD is influenced by the liquid film thickness which is formed inner surface of injection orifice.

• Journal of ILASS-Korea
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• v.2 no.3
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• pp.25-31
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• 1997

This experiment was undertaken to investigate the spray characteristics of the conventional injection system and the ultrasonic energy added injection system. Test fuels include light oil and mixed light-BC oil. The mixed light-BC oil was injected at the normal temperature$(20^{\circ}C)$ and the high temperature$(95{\pm}2^{\circ}C)$ and injection pressure was $120kg/cm^2$. Sauter mean diameter was measured under the variation of the spray distance. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. It is also found that the condition of the ultrasonic energy added injection and high temperature injection generates the smaller droplets than that of the conventional injection.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.57-62
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• 2001

EFI system has severe problems of heavy HC emission generated by large fuel droplets and non-uniform air-fuel mixture. Therefore, various atomization techniques are being developed in order to reduce HC emission. The one among those techniques is ar shrouded injector, which has better atomization ability and demands less power loss than other atomizers. Thus, the development of this air shrouded injector can be major topic to cope with international emission regulation. Nevertheless, there are few domestic and foreign studies which deal with air shrouded injector. In this study, the spray characteristics and atomization mechanism of the representative air shrouded injector were analyzed using PDPA system. From experimental results, the definite standards of air shrouded injector's spray characteristics were established.