• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.6
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• pp.1941-1947
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• 1996

Droplet size measurement technique was established for the sprayed viscous fluid by virtue of the installation of the sprayed-droplet size measurement system employing light scattering method. Atomization test results showed that the mean droplet size of the sprayed viscous fluid is decreased with the increase of the mass ratio of air to fuel and in case of the same air/fuel ratio, also with the increase of viscous fluid flow rate, and is increased with the distance from atomizer tip. Basic design data for the manufacture of external-mixing type, Y-Jet type, and internal-mixing type atomizers was acquired from the atomization tests.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1056-1067
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• 1997

Present study visualized flow pattern and investigated spray characteristics of twin-fluid atomization with converging-diverging nozzles. Particle sizes were measured by using the Malvern particle analyzer, and the radial size distributions were evaluated by using the tomographic transform technique. The results show that the SMD generally increases in the radial direction at a prescribed liquid flow rate and the increasing rate in the SMD becomes gradual as atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR (gas/liquid mass ratio). The atomization performance of the protrusion-type nozzle turned out to be superior to that of the flush-type. However, in the case of the protrusion-type, flow separation occurs outside the liquid delivery tube when the pressure at the gas nozzle chamber is high enough, which may deteriorate the atomization performance.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.205-211
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• 2018

Y-jet nozzle has various advantages over other twin-fluid nozzles and are used in industrial boilers. However, it costs large energy consumption because of assisted air and its design is complex. The Y-jet nozzle is consisted of a liquid and gas port and a mixing chamber. The diameter of the port and the length of the mixing chamber greatly affect spray and atomization characteristics, therefore, they are the most important factors in nozzle design. In this study, The experimental setup is consisted of a laboratory scale spray system. The characteristics of the Y-jet nozzle according to the design parameters were observed. As a result, it was found that the length of the mixing chamber did not have effect on the flow rate and the choking condition. The droplet size was measured using a Malvern type measuring device. In addition, measurements were conducted in the front and the right directions of the nozzles. Based on the results, the SMD View Ratio is defined. It is the asymmetrical design characteristics of the Y-jet nozzle.

• Journal of ILASS-Korea
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• v.6 no.1
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• pp.9-17
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• 2001

The effect of air entrainment in twin-fluid spray structure is investigated experimentally by varing the amount of itemizing air. The air entrainment is expected to affect on droplet size and velocity, droplet number density, turbulent kinetic energy and vorticity. PDA(Phase Doppler Anemometer) and PIV(Particle Image Velocimetry) system are used to measure those important factors in analyzing spray structure. The results show that spray structure consists of three distinctive regions ; the atomizing region near nozzle, characterizing strong convective effect, the central core region where droplets are accelerated, and the spray sheath region where droplets are decelerated due to air entrainment. The local air entrainment rate is largest near nozzle, characterizing strong turbulent kinetic energy and vorticity but deceases along axial distance.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.338-343
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• 2003

Computations were performed to investigate the spray characteristics of the twin fluid nozzle in three stage heavy-oil combustion burner. The burner geometry and flow conditions were provided by a burner company. The goal of the study is to estimate mean droplet size, initial velocity and spread factor of the nozzle through comparison between experiments and numerical analyses. Air stage ratio is 2:4:4 by mass, and O2 in exhaust gas is about 4 % by volume. Here, the agreement between the experiment and numerical analyses is evaluated by NOx generation. Spray characteristics will be linearly interpolated between fuel consumption rate l20L/h and 240 L/h.

• Journal of ILASS-Korea
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• v.24 no.3
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• pp.137-144
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• 2019

The Y-jet nozzle has benefits such as simple design and wide operating conditions. Because of these benefits, it is used in various combustion devices including industrial boilers. The most important variables in the design of the Y-jet nozzle are the mixing chamber length, the supply diameter of the liquid fuel and gas, and the exit orifice diameter. In addition, because of the use of a twin-fluid, optimized data is required depending on the spray condition. In this study, spray experiment was carried out under the pressure condition of 7 bar or more, which is the spraying condition used in industry. There was no change in flow rate with the length of the Y-jet nozzle mixing chamber, but the difference in SMD was confirmed. Adjusting the exit orifice diameter is most important to achieve the desired flow rate. Changes in the liquid and gas inlet port diameters ratio were found to be help improve the operating range and significant difference in SMD was observed.

• Journal of Digital Convergence
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• v.10 no.5
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• pp.283-288
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• 2012

This study was undertaken to investigation the spray characteristics of the twin fluid atomization nozzle system. The light oil was injected at the normal temperature and injection pressure was 5 bar - 10 bar by 1 bar and volume flow was 0.5, 1.0 and 2,0 mmH2O(X10-2). We measured the SMD of sprayed droplet to study spray characteristics. The following conclusions were reached from the results of these study. 1. The more injection pressure increased, the more SMD decreased. 2. The more measuring distance between pressure nozzle tip and analyser beam increased, the more SMD increased. 3. SMD of the blower-air-added injection system were shown, increasing volume flow decreased respectively. The result of this study indicated the blower-air-added injection system induced beneficial changes in SMD. And it will be considered important indicator for spray characteristics design and performance evaluation of twin fluid atomization nozzle system.

• Journal of ILASS-Korea
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• v.3 no.2
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• pp.14-23
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• 1998

The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2147-2159
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• 1991

The effects of principal dimensions of internal mixing twin-fluid atomized and operating conditions on the atomizing characteristics are experimentally investigated. The tests are conducted over the wide range of air/liquid ratio to predict influences of the diameter and length of nozzle, contacting angle between air and liquid in the mixing chamber, and air orifice diameter on the mean drop size(SMD), spray angle, distribution of drop size, and spray dispersion, And also, initial distribution of liquid column by air stream within the mixing chamber are observed through the transparent nozzles. A He-Ne laser particle sizer(MALVERN Model 2604) was used to measure the Sauter.s mean diameter( $D_{321}$) and droplet sizes distribution. In this experiment the air/liquid ratio, mixing length and nozzle diameter have a great influence on SMD, spray angle, droplet sizes distribution and spray dispersion.

• Journal of Biosystems Engineering
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• v.27 no.4
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• pp.317-326
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• 2002

Characteristics of a twin-fluid spray with ultrasonic vibration were examined in order to obtain a high efficiency of cold-fog spray of the automatic pest control machine which has been widely used in protected horticulture recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive $\pi$-type vibrator were used applied as the ultrasonic transducers with a frequency of 28 kHz. All experiments were conducted in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving-quality method by ultrasonic forced within liquid, and a combined-use method with both of the indirect vibration method and the improving quality method. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 10% and especially much more in the case of the combined-use method.