• International Journal of Automotive Technology
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• v.1 no.2
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• pp.95-100
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• 2000

The droplet and the turbulent characteristics of a counterflowing internal mixing pneumatic nozzle mainly focused. The measurements were made using a Phase Doppler Particle Analyzer under the different air pressures. The nozzle with tangential-drilled holes at an angle of 30 to the central axis has been designed. The spatial distributions of velocities, fluctuating velocities, droplet diameters and SMD were quantitatively and qualitatively fluctuating velocities were substantially higher than the radial and the tangential ones. This implies that the disintegration process is enhanced with the higher air pressure. The larger droplets were detected near the spray centerline at the upstream while the smaller ones were generated at the downstream. This was attributed to the lower rates of spherical particles which were not subject to instantaneous breakup. However, substantial increases in SMD from the central part tower spray periphery were predictable in downstream regions.

• Journal of ILASS-Korea
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• v.11 no.3
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• pp.176-189
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• 2006

In the present study, capability of improving the liquid atomization of a high-speed liquid jet by using wall impingement is explored, and its application to a jet engine atomize. is demonstrated. Water is injected from a thin nozzle. The liquid jet impinges on a wall positioned close to the nozzle exit, forming a liquid film. The liquid film velocity and the SMD were measured with PDA and LDSA, respectively. It was shown that the SMD of the droplets was determined by the liquid film velocity and impingement angle, regardless of the injection pressure or impingement wall diameter. When the liquid film velocity was smaller than 300m/s, a smaller SMD was obtained, compared with a simple free jet. This wall impingement technique was applied to a conventional air-blasting nozzle for jet engines. A real-size air-blasting burner was installed in a test rig in which three thin holes were made to accommodate liquid injection toward the intermediate ring, as an impingement wall. The air velocity was varied from 41 to 92m/s, and the liquid injection pressure was varied from 0.5 to 7.5 MPa. Combining wall impinging pressure atomization with gas-blasting produces remarkable improvement in atomization, which is contributed by the droplets produced in the pressure atomization mode. Comparison with the previous formulation for conventional gas-blasting atomization is also made, and the effectiveness of utilizing pressure atomization with wall impingement is shown.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.95-100
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• 2002

This study was experimentally performed to investigate flow characteristics of spray droplets in the wind tunnel. Behavior of the spray droplets in the pipe was observed and the deposition rate of droplets on the surface of pipe as liquid film was measured. The experiments were carried out for a variety of parameter, such as velocity of feed air, spray angle of nozzle, and diameter of droplet. From the visual observation of the spray droplets in the pipe and the measurement of deposition rate on the pipe, the general understanding of droplets behavior for desuperheater was provided.

• Journal of Mechanical Science and Technology
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• v.19 no.7
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• pp.1478-1487
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• 2005

A small mixed-type turbine with a diameter of 19.9 mm has been substituted for a rotational part of pencil-type air tool. Usually, a vane-type rotor is applied to the rotational part of the air tool. However, the vane-type rotor has some problems, such as friction, abrasion, and necessity of accurate assembly etc.,. These problems make the life time of the vane-type air tool short, but air tools operated by mixed-type turbines are free of friction and abrasion because the turbine rotor dose not contact with the casing. Moreover, it is assembled easily because of no axis offset. These characteristics are merits for using air tools, but loss of power is inevitable on a non-contacting type rotor due to flow loss, tip clearance loss, and profile loss etc.,. In this study, four different rotors are tested, and their characteristics are investigated by measuring the specific output power. Additionally, optimum nozzle location against the rotor is studied. Output powers are obtained through measured pressure, temperature, torque, rotational speed, and flow rate. The experimental results obtained with four different rotors show that the rotor blade shape greatly influences to the performance, and the optimum nozzle location exists near the mid span of the rotor.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.356-367
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• 2001

A numerical analysis on branch type sparger in drain tank for depressurization is performed to investigate the flow characteristics due to the change of design factor. As the result of this study, sparger\\`s flow resistance coefficient(K) is 3.53 at the present design condition when engineering margin for surface roughness is considered as 20%, and flow ratio into branch pipe ($Q_s/Q_i$) is 0.41. The correlation for calculating flow resistance coefficients as design factor is presented. Flow resistance coefficient is increased as section area ratio of branch pipe for main pipe and outlet nozzle diameter of main pipe decreasing, but the effects of branch angle and inlet flow rate of main pipe are small. As the change rate of ($Q_s/Q_i$)becomes larger, the change rate of flow resistance coefficient increases. The rate of pressure loss has the largest change as section area ratio changing. The condition of maximum flow resistance in sparger is when the outlet nozzle diameter ratio of main pipe ($D_e/D_i$) is 0.167, the section area ratio ($A_s/A_i$) is 0.1 and the branch angle ($\alpha$) is 55^{\circ}$.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.79-84
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• 2004

For the non-premixed interacting jet flames, it has been reported that if eight small nozzles are arranged along the circle of 40 $^{\sim}$ 72 times the diameter of single jet, the flames are not extinguished over 2oom/s. In this research, experiments were extended to the partially premixed cases to reduce both flame temperature and NOx emission. Nine nozzles were used- eight was evenly located along the perimeter of the imaginary circle and one at the geometric centre. The space between nozzles, S, the equivalence ratio, ${\Phi}$, the exit velocity and the role of the jet from the centre nozzle were considered. Normally, flame was lifted and flame base was located inside the imaginary circle made by the nozzle. As nozzles went away from each other, blowout velocity increased and then decreased. The maximum blowout velocity diminished with the addition of air to the fuel stream. When the fuel and/or oxidizer were not fed through the centre nozzle, the maximum blowout velocity obtained by varying Sand ${\Phi}$ was around 160m/s. Optimum nozzle separation distance at which peak blowout velocity obtained also decreased with ${\Phi}$ decrease. Flame base became leaner as approaching to the blowout. It seemed that lots of air was supplied to the flame stabilizing region by the entrainment and partially premixing. To approve this idea and to enhance the blowout velocity, fuel was supplied to the centre region. With the small amount of fuel through the centre nozzle, partially premixed flame could be sustained till sonic velocities. It seemed that the stabilizing mechanism in partially premixed interacting flame was different from that of non-premixed case because one was stabilized by the fuel supply through the centre nozzle but the other destabilized.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.71-79
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• 2005

For the non-premixed interacting jet flames, it has been reported that if eight small nozzles are arranged along the circle of $40{\sim}72$ times the diameter of single jet, the flames are not extinguished even in 200m/s. In this research, experiments were extended to the partially premixed cases to reduce both flame temperature and NOx emission. Nine nozzles were used- eight was evenly located along the perimeter of the imaginary circle and one at the geometric centre. The space between nozzles, S, the equivalence ratio, ${\phi}$, the exit velocity and the role of the jet from the centre nozzle were considered. Normally, flame was lifted and flame base was located inside the imaginary circle made by the nozzle. As nozzles went away from each other, blowout velocity increased and then decreased. The maximum blowout velocity diminished with the addition of air to the fuel stream. When the fuel and/or oxidizer were not fed through the centre nozzle, the maximum blowout velocity obtained by varying S and ${\phi}$ was around 160m/s. Optimum nozzle separation distance at which peak blowout velocity obtained also decreased with ${\phi}$ decrease. Flame base became leaner as approaching to the blowout. It seemed that lots of air was supplied to the flame stabilizing region by the entrainment and partially premixing. To approve this idea and to enhance the blowout velocity, fuel was supplied to the centre region. With the small amount of fuel through the centre nozzle, partially premixed flame could be sustained till sonic velocities. It seemed that the stabilizing mechanism in partially premixed interacting flame was different from that of non-premixed case because one was stabilized by the fuel supply through the centre nozzle but the other destabilized.

• Fire Science and Engineering
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• v.31 no.4
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• pp.59-64
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• 2017

In the present experimental study, the liquid pool fire extinguishment performance of twin-fluid nozzle was preliminarily examined. For the liquid pool fire, the ethanol of 1200 ml (volume) was prepared, and two kinds of air flow rate conditions (40 l/min and 70 l/min) were tested at the constant water flow rate condition of 632 ml/min. In the present experimental ranges, the fire extinguishment experiments were carried out using the twin-fluid nozzle and its spray characteristics (i.e., SMD (Sauter Mean Diameter) and flow distribution) were investigated. As a result, at the higher air flow rate, the liquid pool fire was extinguished quickly and successfully, which was discussed using the visualization and spray characteristics of twin-fluid nozzle. In addition, through the comparison with some of previous results, it was found that potentially, the twin-fluid nozzle can extinguish the liquid pool fire under the smaller water flow rate condition, as compared with the single-fluid nozzle.

• 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 Energy Engineering
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• v.23 no.4
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• pp.130-140
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• 2014

Rotary kiln burner has been developed continuously to improve process efficiency and exhaust emission. In this study, the characteristics of the flame and exhaust emission were numerically analyzed according to the diameter of primary air nozzle, equivalent ratio of burner, and equivalent ratio at center and side nozzle for development of multi-nozzle burner in the COG(Coke Oven Gas) rotary kiln for sintering iron ore. The results indicated that the flame length and $NO_x$ emission increase, as the diameter of primary air nozzle and equivalent ratio of burner increase. And according to the change of equivalent ratio at the center and the side of the nozzle, the flame length and average temperature in the kiln show very little change but the $NO_x$ emission shows obvious difference. In conclusion, the best design conditions which have satisfying flame length, average temperature and $NO_x$ emission are as follows: $D_2/D_1$ is 1.33, equivalent ratio of burner is 1.25 and center nozzle conditions are Rich.