• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.201-207
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• 2003

Characteristic of turbulent nonpremixed interacting flames are investigated experimentally 8 or 9 nozzles are arranged in the shape of matrix or circle. When there is no center nozzle, flame is more stable than with center nozzle case. It is shown that these blowout limit enlargements are related with the recirculation of burnt gases. The interacting flame base was not located at the stoichiometric point. NO concentrations of interacting flame are smaller than that of single flame using same area nozzle.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.14-15
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• 2006

In this study, a new laval type nozzle was designed and manufactured. Using this nozzle tin powder was produced in close coupled system by using nitrogen gas at different operating conditions. The results showed that the increasing the gas pressure up to 1.47 MPa reduced the mean powder size down to 11.39 microns with a gas/melt mass flow rate ratio of 2.0. Powders are spherical in shape and have smooth surfaces.

• 한국항공우주학회지
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• 제37권5호
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• pp.476-482
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• 2009

본 논문에서는 Fluent의 Spalart-Allmaras 난류모델을 적용하여 연소실 내부에 설치된 핀틀 형상이 핀틀 추진기관 추력 크기에 미치는 영향을 수치해석으로 분석하였다. 핀틀이 존재하면 노즐목을 지나는 질량 유량율은 이론적으로 예측된 값 보다 항상 작았으며, 핀틀 직경이 커질수록 노즐목에서 경계층 두께가 차지하는 비율이 증가되어 노즐목의 질량 유량율이 더욱 감소하였다. 핀틀 직경이 커질수록 핀틀 팁에 나타나는 재순환 영역의 압력에 의한 추력은 증가하지만 노즐 및 연소실 압력에 의한 추력은 감소하여 총 추력은 핀틀 직경이 작은 것 보다 감소하였다. 핀틀 추진기관의 비추력은 큰 차이가 없었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.51-55
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• 2003

In this research, authors tried to measure the shape of the nozzle throat of KL-3 engines, which is the main engine of KSR-III rocket, to find the increase of nozzle area caused by the thermal ablation. For the purpose, we invented an image-based method instead of the 3D pointer, which is actually inaccessible to such large scale engines. As a result, our equipment showed satisfactory accuracy and performance. Analysing the results of experiments, we find that the pattern of ablation is determined by the spray pattern and that the process of thermal ablation phenomena can be categorized in three regimes - the first regime that the shape of nozzle throat is maintained and ablation is negligible, the second regime that saw-tooth form is developed and ablation is accelerated, and the third regime that the saw-tooth form is already established and the growth of ablation rate is reduced. Also, we find that the ratio of area increase after 60 seconds combustion is +5.82% and conclude that this figure is acceptable and satisfactory.

• 소성∙가공
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• 제3권1호
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• pp.110-119
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• 1994

In this paper, a new forming process of large-size forgings of converged nozzle-shape is developed by the experimental study using the incremental forging method and combined forming method. The development of the forming process is focused on the manufacturing of large-size forgings by the press with medium load capacity. Various related processes are proposed and modelling experiments using plasticine are carried out. Thus, the incremental forging method for expanding is recommanded from the study of formability and forming load, etc. The selected process is then subjected to modelling experiments of lead and the design parameters such as preform for final process, die-width of the upper die and reduction amount of each stroke are determined. In order to verify the effectiveness of the selected process, 1/7 scale prototype experiment of the real material is carried out. Forgings of converged nozzle shape can be produced by the developed process within the limit loads and with the simple tools.

• 한국유체기계학회 논문집
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• 제16권6호
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• pp.32-39
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• 2013

In the present study, three-dimensional aerodynamic optimization of high pressure turbine nozzle for turbofan engine was performed. For this, Kriging surrogate model was built and refined iteratively by supplying additional experimental points until the surrogate model and CFX result has effective difference on objective function. When the surrogate model satisfied this reliability condition and developed enough, optimum point was investigated. Commercial program PIAnO was used for optimization process and evolutionary algorithm was used for searching optimum point. As a result, difference between estimated value from Kriging surrogate model and CFD result converges within 0.01% and the optimized nozzle shape has 0.83% improved aerodynamic efficiency.

• 대한기계학회논문집B
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• 제35권10호
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• pp.1005-1012
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• 2011

본 연구의 목적은 원형과 타원형 노즐에 발생되는 캐비테이션 유동에 대해 수치 계산을 통해 각각의 특성을 파악하는 것이다. 수치해석을 위해 상용코드인 FLUENT 6.2 을 사용하였고, 실험결과의 캐비테이션 형태와 수치계산에서 얻은 결과를 비교함으로써 계산결과의 타당성을 확인하였다. 주목할만한 결과로는 원형 노즐 내부의 캐이테이션 형상은 노즐 축방향으로 대칭적인 원통형을 가지는 반면, 타원형 노즐의 경우 장축의 캐이테이션 길이가 단축의 캐이테이션 길이보다 긴 말발굽 (horseshoe) 형태가 관찰되었다. 또한, 타원형 노즐의 경우 오리피스의 반경방향 속도는 오리피스의 장, 단축에서 확연히 다른 분포가 관찰되었다.

• 한국기계가공학회지
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• 제21권6호
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• pp.15-21
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• 2022

This study considered the internal flow considering the internal shape of the CNG filling nozzle, which is widely distributed in Korea. The CNG filling nozzle is the last part to pass through in the CNG filling process and has a significant influence on the filling efficiency. The mechanism was identified by disassembling the CNG filling nozzle and performing a flow analysis according to the mechanism. Consequently, the energy loss owing to eddy currents in the flow was determined, and modeling was proposed to reduce the energy loss by simplifying the shape and parts.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1194-1197
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• 2005

Micro nozzle is employed as a dynamic passive valve in micro fluidic devices. Micro nozzle array is used in micro droplet generation in bio-medical applications and propulsion device for actuating satellite and aerospace ship in vacuum environments. Aperture angle and the channel length of the micro nozzle affect its retification efficiency, and thus it is needed to produce micro nozzle precisely. MEMS process has a limit on making a micro nozzle with high-aspect ratio. Reactive ion etching process can make high-aspect ratio structure, but it is difficult to make the complex shape. Focused ion beam deposition has advantage in machining of three-dimensional complex structures of sub-micron size. Moreover, it is possible to monitor machining process and to correct defected part at simultaneously. In this study, focused ion beam deposition was applied to micro nozzle production.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.550-556
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• 2008

The aim of this research is to analyze the influence of motive pressure, driving nozzle position and nozzle throat ratio on the performance of ejector. The experiment was conducted in the variation of motive pressure of 0.196, 0.294, 0.392 and 0.490MPa respectively. The position of driving nozzle was varied in difference locations according to mixing tube diameter(0.5d, 1d, 2d, 3d, 4.15d, 5d and 6d). The experimental results show when the nozzle outlet is located at 3d, the flow characteristics change abruptly. It is shown that the suction flow rate and pressure lift ratio of ejector is influenced by the driving nozzle position. At nozzle position location of the Id of mixing tube diameter the performance of ejector gives the best performance.