• Journal of Power System Engineering
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• v.12 no.3
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• pp.12-18
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• 2008

In the present study, the numerical simulation has been performed to investigate K-factor for temperature variation of working fluid in spray nozzle with orifice. The commercial CFD software, Fluent with the proper modeling was applied for analyzing the internal of the spray nozzle. Numerical result for K-factor at $20^{\circ}C$ agrees with the experimental result that it applied n=0.5 within about 7% error. The pressure drop inside nozzle is showed 20% passing swirler, 70% in the region between the outlet of swirler and the orifice and 10% at the outlet of orifice. As the operating pressure is increased, K-factor is decreased by effect of flow resistance at it's inlet before pass swirler. The temperature increase of working fluid reduced the flow rate according to reducing of density, and average 1.23% decrease is showed in the present research.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.22-28
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• 2003

Predictions of the fuel spray dispersion and mixing processes are very important to improve the fuel consumption and exhaust emissions in GDI engines. Numerical and experimental analysis of the sprays with a swirl injector have been conducted. A numerical analysis is carried out using KIVA-II code with modified spray models. Experimental measurements are performed to show the global spray images and the local images near nozzle tip using laser sheet visualization technique. Computed and measured spray characteristics such as spray width, tip penetration are compared, and good agreements can be achieved. The spray head vortex is stronger as the injection pressure increases, but numerical calculations cannot show the head vortex properly.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.1
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• pp.37-42
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• 2000

액체 분무가 벽면의 평평한 면에 충돌할 때의 거동에 대해 실험을 통하여 조사하였다. 각 분사노즐과 벽면까지의 거리 그리고 분사 속도에 있어서 충돌점에서의 액체 액막의 비산 거동과 평면에서의 액막의 흐름에 대하여 관찰하였다. 충돌점에서 비산하는 액적의 비산율을 정량적으로 측정하였다. 분사속도가 증가에 의해 충돌 거동은 5개의 영역으로 분류되며, 분사속도가 증가하면 비산율도 증가하게 된다. 또한, 충돌거리가 분무의 분열점보다 길때의 분사량의 약 반 정도가 비산하게 되는 결과가 얻어졌다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.317-323
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• 2020

In this study, the correlations between flow rate, exhaust pressure, and droplet mean diameter with the shape factor of a water curtain nozzle were investigated. To analyze the flow coefficient and the distribution constant on the effects of the hydraulic diameter, five nozzles (D5W3, D5W6, D5W8, D4W6, and D7W6) were mocked up with a consideration of the internal diameter and width. The results showed that the flow coefficient increased in proportion to the constant 0.79 and 62.8 of the hydraulic diameters according to the diameter. As the nozzle width increased, the average droplet size decreased to the -0.235 exponential of the pressure. The average volume was reduced, in which the size distribution of the volume indeterminate decreased with increasing pressure for the same nozzle of the water-curtain. The distribution constants of droplet increased in proportion to the 0.258 exponential of the hydraulic diameter and 244.21. These results are expected to be useful to the design of pressure, flow meter, and average droplet size from a water curtain nozzle to predict the flow characteristics.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.312-314
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• 2007

본 논문에서는 비데용 물 분사 노즐의 내부유동을 가시화하기 위해서 여러 가지 설계변수에 관한 연구가 수행되었다. 특히 물 분사에 만 의존했던 과거의 세정시스템과는 달리 물과 공기를 혼합해서 물도 절약하고 세정의 효과도 높이고자 하는 기술을 개발하고자 했다. 상용코드인 CFD-ACE+를 이용하여 내부유동 특성을 관찰했고 여러 가지 인체 공학적인 설계가 되도록 다양한 각도에서 검토되었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.53-60
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• 2002

Based on the analyses of the single transverse injection in supersonic flow fields, the mixing characteristics of dual transverse injection of hydrogen in supersonic air flow are studied with computational methods. Three-dimensional Navier -Stokes and the k-$\omega$ SST turbulence model were used. A parametric study is conducted with the variation of the distance between two injectors. The flow patterns and the mixing characteristics of two injection flows are very different from each other, and the flow patterns and the mixing characteristics of the rear injection flow are strongly influenced by those of the first injection flow. The increase of the distance between two injectors up to a specific distance results in the increase of mixing rate and penetration of fuel. However, the increase of the distance over the specific distance results in the decrease of mixing rate and penetration of fuel. From the results it can be stated that there exists a distance between two injectors for optimum mixing characteristics.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.145-145
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• 2012

• Journal of Energy Engineering
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• v.28 no.1
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• pp.57-64
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• 2019

In this study, the blasting nozzle for surface treatment of the curved surface of parts in power plant industry was designed and the cleaning performance was examined through the compressible flow analysis. At this time, the outlet of the curved nozzle was designed as a curved surface along the surface of the part. After the nozzle was made by 3-D printing, the abrasive was sprayed on the surface of the cylindrical specimen and the cleaning performance test was performed. The effective cleaning area obtained after the analysis was similar to the size and shape of the effective cleaning area obtained after the experiment. From this, the validity and effectiveness of the curved nozzle design was confirmed.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1997.06c
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• pp.74-79
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• 1997

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.04a
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• pp.63-72
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• 1997

본 논문은 분사제트 주위에 형성되는 와류를 조절하여 제트를 제어하기 위하여 유동가시화, 속도분포 및 난류성분을 측정하는 실험을 수행하였다. 와류를 조절하기 위한 방법으로 제트노즐 주위에 환형관을 설치하여 환형관으로부터 2차제트를 분사 또는 흡입함으로써 제트주위에 형성되는 전단류를 변화시켰다. 2차제트 분사시 주제트 주위에 형성되는 와류의 발달을 억제함으로써 제트 포텐셜코어의 길이가 아주 길어지는 제트유동을 얻을 수 있었다. 환형관으로부터 주제트주위의 유체를 흡입하는 경우 제트주위의 전단류가 흡입비 R=1.3∼l.65에서 대류불안정성에서 절대불안정성으로 바뀜으로써 형성된 와류가 하류에서 제트중심부까지 발전, 결합되는 것을 방지하여 더 긴포텐셜코어와 중심에서 낮은 난류강도를 얻었다. 위의 결과는 환형관 주위에 부착한 깃의 높이 변화에 따라서 변화하였는데, 이것은 깃이 환형관을 통한 흡입유동의 유로역할을 함으로써 제트밖으로부터 흡입되는 것을 방지할 수 있었다. 분사제트 벡터링을 위하여 제트노즐 주위의 환형관을 이등분하여 한쪽으로만 제트주위의 유동을 흡입함으로써 제트주위에 다른 전단류를 형성함과 동시에 Coanda효과를 이용하여 분사제트를 편향시켰다. 편향되는 정도 및 난류성분은 홉입속도 비에 따라서 크게 바뀌었다.