• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1616-1623
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• 2001

A basic experimental study has been carried out to find out the design parameters of fuel 2-staging atomizers in order to reduce nitrogen oxides(NOx) rate emitted from the steam boilers used the liquid fuel. The heavy fuel oil(B-Coil) and fuel 2-staging Y-jet twin-fluid atomizers were adopted in this study. The results of this paper were obtained from the real as well as the model scale atomizers. In the case of model atomizers test, NOx reduction rate was strongly dependent on the staged fuel rate, but it was weakly dependent on the injection hole arrangement and air swirl conditions. The real scale atomizers was designed and manufactured on the base of these test results, and those was mounted and operated in the real boiler generates 185 ton steam per an hour. The reduction rate of the model and real plant was reached 10∼30% of base NOx by atomizers. but dust was sharply increased in the low O$_2$combustion region of the real plant.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1330-1336
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• 1990

The factors to act on atomization of liquid fuel are viscosity, geometric shape of nozzle, atomizing pressure, etc. Most of high viscous liquid fuels show decrease in viscosity by raising the preheat temperature, but the viscosity of liquid fuel like CWM does not readily change with fuel temperature. As an experimental study to investigate the atomizing characteristics of CWM, CWM fuel is atomizing with a twin-fluid atomizer, and the effects of the geometric shape of spray nozzle on atomization are investigated by measuring the Sauter`s Mean Diameter (SMD) of CWM. The summarized results obtained in this study are as follows ; (1) As the ratio of the mass flows of atomizing air to that of fuel (W$_{a}$ /W$_{1}$) increases, 능 decreases when fuel temperature is constant. (2) At the ratio (t/d) 4 of thickness (t) of spray nozzle hole to the diameter (d) of the hole, there is the best atomization. And SMD decreases when t/d is between 1 to 4 and increases when t/d > 4.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3377-3385
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• 1994

This paper introduces empirical correlations to obtain the gas/liquid flow rates and the spray drop size of low viscosity liquid injected by Y-jet twin-fluid atomizers. The gas flow rate is well correlated with the gas injection pressure and the mixing point pressure, based on the compressible flow theory. Similarly, the liquid flow rate is determined by the liquid injection pressure and the mixing point pressure, and a simple correlation for the liquid discharge coefficient at the liquid port was deduced from the experimental results. The mixing point pressure, which is one of the essential parameters, was expressed in terms of the gas/liquid flow rate ratio and the mixing port length. Disintegration and atomization mechanisms both within the mixing port and outside the atomizer were carefully re-examined, and a "basic" correlation form representing the mean diameter of drops was proposed. The "basic" correlation was expressed in terms of the mean gas density within the mixing port, gas/liquid mass flow rate ratio and the Weber number. Though the correlation is somewhat complicated, it represents the experimental data within an accuracy of ${\pm}15%$.EX>${\pm}15%$.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.57-66
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• 1985

This paper deals with an experimental study on a liquid atomization to investigate the break- up mechanism of a liquid film flow which is formed by a high speed air flow in parallel direction and an atomization characteristics of a liquid film flow in order to provide the basic data for the development of the twin fluid atomizer. Authors had built the simplified, transparent new devices which can form a uniform thickness of liquid film and an electrical measuring circuit of the liquid film thickness. By introducing the new devices and the measuring circuit, the time variation of a liquid film thickness the mean diameter of the droplets, the droplet size distribution, the degree of the dispersion and the atomization rate of a liquid film are measured experimentally. As the analysis of the study, it can be said the experimental investigation will fairly contribute for further study in this field of study.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.693-698
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• 2001

An experimental study was carried out with an aerated nozzle. This nozzle was well known that the performance of the atomization is better than other ones even though the supplied air pressure is lower than that of them. The purpose of this investigation is to provide the essential information of the aerated nozzle from the nozzle exit. The experimental work was performed in order to analyze the characteristics of the overall flow field from the nozzle exit. The 2-D PDPA system was used to acquire the data in the concerned region. The characteristics of the mean velocity distribution, half-width, and SMD were mainly analyzed. Also the correlation between turbulent kinetic energy and SMD was described with ALR.

• Journal of ILASS-Korea
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• v.26 no.1
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• pp.33-39
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• 2021

Y-jet nozzle has a wide fuel flow rate range and turn-down ratio, thus, it is used in industrial boilers, furnace and agricultural atomizer. However, it has asymmetrical spray characteristics due to the nozzle design factors. Therefore, in this study, asymmetric spraying characteristics of the elliptical Y-jet nozzle was studied by using the lab-scale spray apparatus. As a result, the elliptical Y-jet nozzle had lower gas mass flow rate than circular Y-jet nozzle at same gas pressure, because of bigger shear stress due to the wider inner surface at the elliptical Y-jet nozzle. Larger SMD was measured on the elliptical Y-jet nozzle than the circular Y-jet nozzle. When SMD was measured in the X_Axis direction at the same gas mass flow rate, the elliptical Y-jet nozzle with an aspect ratio of 2:1 showed greater asymmetry than the others.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.125-130
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• 2001

Experimental and analytical researches have been conducted on the twin-fluid atomizers for better droplet breakup during the past decades. But, the studies on the disintegration mechanism still present a great challenge to understand the drop behavior and breakup structure. In an effort to describe the aerodynamic behavior of the sprays issuing from the internal mixing counter-swirling nozzle, the spatial distribution of axial (U) radial (V) and tangential (W) components of droplet velocities are investigated across the radial distance at several axial locations of Z=30, 50, 80, 120 and 170mm, respectively. Experiments were conducted for the liquid flow rates which was kept constant at 7.95 g/s and the air injection pressures were varied from 20 kPa to 140 kPa. Counter-swirling internal mixing nozzles manufactured at angles of $15^{\circ},\;30^{\circ},\;45^{\circ}$ and $60^{\circ}$ the central axis with axi-symmetric tangential-drilled holes was considered. The distributions of velocities and turbulence intensities are comparatively analyzed. PDPA is installed to specify spray flows, which have been conducted along the axial downstream distance from the nozzle exit. Ten thousand of sampling data was collected at each point with time limits of 30 second. 3-D automatic traversing system is used to control the exact measurement. It is observed that the sprays with all swirl angle have the maximum SMD for on air injection pressure of 20 kPa and 140 kPa with centerline, respectively. The nozzle with swirl angle of $60^{\circ}$ has vest performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3179-3186
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• 1993

The study on the spray characteristics of TBI(Throttle Body Injection) injector has been carried out in this paper. The objective of this study is to improve the performance of TBI injector. The increase in the injection pressure and the utilization of assisted air are considered. The spray patten of TBI injector take the hollow-cone shape with $60^{\circ}~70^{\circ}$ spray angle regardless of injection pressure and injection pulse width. SAMD(Sauter Mean Diameter) of water in TBI injector are 510-$550{\mu}m$ and 310-$370{\mu}m$ respectively when injection pressures are $0.75 kgf/cm^{2}$ and $2.8 kgf/cm^{2}$. Then SMD of gasoline is estimated 380~$410{\mu}m$ and 230~$280{\mu}m$ respectively. The improvement of spray characteristics in TBI injector can be obtained with assisted air. If $W_{A}/W_{L}$ was over 0.2, SMD of water can be made under $50{\mu}m$.