• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.713-721
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• 2004

Variable air intake and variable exhaust nozzle of hypersonic engines are designed and tested in this study. Dimensions for variable geometry air intake, ram combustor and variable geometry exhaust nozzle are defined based on the requirements of a pre-cooled turbojet engine. Hypersonic Ramjet Engine is designed as a scaled test bed for each component. Actuation forces of moving parts for variable intake and variable nozzle are reduced by balancing the other force in the opposite direction. A demonstrator engine which includes variable intake and variable nozzle is designed and the components are fabricated. Composite material with silicone carbide is applied for high temperature parts under oxidation environment such as leading edge of the variable intake and combustor liner. Internal cooling structure is adopted for both moving and static parts of the variable nozzle. Pressure recovery and mass capture ratio of the variable intake at Mach 5 is obtained by a hypersonic wind tunnel test. Flow characteristics of the variable nozzle are obtained by a low temperature flow test. Wall temperature and heat flux of the nozzle at Mach 3 is obtained by a firing test. As results, the intake and the nozzle are proved to be used at designed pressure and temperature environment.

• 한국터널지하공간학회 논문집
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• 제14권5호
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• pp.517-528
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• 2012

연마재 워터젯을 이용하여 암반을 굴착하기 위해서는 노즐이 삽입되고 절삭하는 연속적 공정이 요구된다. 본 연구에서는 노즐이 삽입되기 위한 충분한 절삭 폭을 확보하기 위해 한 쌍의 연마재 워터젯 노즐을 이용하여 암석 절삭실험을 실시하였다. 한 쌍의 노즐형태와 위치에 따른 기하학적 변수에 따라 암석 절삭형상과 절삭 폭이 달라지는 것을 확인하였다. 정의된 기하학적 변수에 따라 절삭 깊이 및 폭을 측정하여 암반에 형성되는 절삭단면 형상을 분석하였다. 그 중 노즐 삽입이 가능한 기하학적 변수를 제시하고 현장적용 가능성에 대해 검증하였다.

• Current Optics and Photonics
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• 제8권3호
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• pp.300-306
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• 2024

To solve the nozzle swing angle non-contact measurement problem, we present a nozzle pose estimation algorithm involving weighted measurement uncertainty based on rotation parameters. Firstly, the instantaneous axis of the rocket nozzle is constructed and used to model the pivot point and the nozzle coordinate system. Then, the rotation matrix and translation vector are parameterized by Cayley-Gibbs-Rodriguez parameters, and the novel object space collinearity error equation involving weighted measurement uncertainty of feature points is constructed. The nozzle pose is obtained at this step by the Gröbner basis method. Finally, the swing angle is calculated based on the conversion relationship between the nozzle static coordinate system and the nozzle dynamic coordinate system. Experimental results prove the high accuracy and robustness of the proposed method. In the space of 1.5 m × 1.5 m × 1.5 m, the maximum angle error of nozzle swing is 0.103°.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.35-41
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• 2010

Experimental study on the flow field inside the nozzle for radial turbine was performed. At design point, the pressure is high and the Mach number is low at the pressure side of the nozzle inlet semi-vaneless space as the flow turns through the nozzle vanes. As the flow accelerates through the nozzle passage to the throat the pressure level at the pressure and suction sides becomes similar. The flow continued accelerating from the throat to the inlet of turbine wheel and the pressure field became uniform in the circumferential direction in the vaneless space. In high expansion ratio condition, strong favorable pressure gradient band region occurred just after the throat in the semi-vaneless space in the circumferential direction and the pressure became uniform in the circumferential direction after this band. In low expansion ratio condition, core flow acceleration is dominant after the throat and this non-uniform pressure field reached to the inlet of turbine wheel.

• International Journal of Aeronautical and Space Sciences
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• 제7권1호
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• pp.27-42
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• 2006

A method to design the contour and conception of a plug nozzle of arbitrary shape, but specified exit flow conditions is presented. Severals shapes can be obtained for exit Mach number by changing the specific heats ratio. The characteristics of the nozzle in terms of length, weight and pressure force exerted on the wall are compared to the Minimum Length Nozzle and found to be better. Our field of study is limited to the supersonic mode to not to have the dissociation of the molecules. The design method is based on the use of the Prandtl Meyer function of a perfect gas. The flow is not axial at the throat, which may be advantageous for many propulsion applications. The performance benefits of the plug nozzle compared to the Minimum Length Nozzle are also presented.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.1-30
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• 2008

When the stagnation temperature of a perfect gas increases, the specific heats and their ratio do not remain constant any more and start to vary with this temperature. The gas remains perfect; its state equation remains always valid, except, it is named in more by calorically imperfect gas. The aim of this work is to trace the profiles of the supersonic axisymmetric Minimum Length Nozzle to have a uniform and parallel flow at the exit section, when the stagnation temperature is taken into account, lower than the dissociation threshold of the molecules, and to have for each exit Mach number and stagnation temperature shape of nozzle. The method of characteristics is used with the algorithm of the second order finite differences method. The form of the nozzle has a point of deflection and an initial angle of expansion. The comparison is made with the calorically perfect gas. The application is for air.

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.70-81
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• 2017

Various components of an engine nozzle are modeled as flexible multi-body components that are operated under high temperature and pressure. In this paper, in order to predict complex behavior of an engine nozzle, thermo-fluid-flexible multi-body dynamics coupled analysis framework was developed. Temperature and pressure on the nozzle wall were obtained by the steady-state flow analysis for a two-dimensional nozzle. The pressure and temperature-dependent material properties were delivered to the flexible multi-body dynamics analysis. Then the deflection and strain distribution for a nozzle configuration was obtained. Heat conduction and thermal analyses were done using MSC.NASTRAN. The present framework was validated for a simple nozzle configuration by using a one-way coupled analysis. A two-way coupled analysis was also performed for the simple nozzle with an arbitrary joint clearance, and an asymmetric flow was observed. Finally, the total strain result for a realistic nozzle configuration was obtained using the one-way and two-way coupled analyses.

• 한국항공우주학회지
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• 제43권6호
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• pp.479-487
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• 2015

반사식 충격관 터널에서의 노즐의 정체조건은 반사충격파 이후의 유동조건에 해당된다. 반사식 충격관 터널에서 반사충격파 이후의 유동조건을 계산할 때, 노즐이 없는 충격관 튜브와는 달리, 노즐방향으로의 흐름을 고려하여야 한다. 본 연구에서는 노즐목의 크기에 따른 반사충격파 이후의 조건, 즉 노즐 정체실 조건의 특성을 이론적, 실험적, 그리고 수치해석적으로 다루었다. 노즐목의 크기가 증가할수록 정체실의 조건이 감소함을 알 수 있으며, 노즐목에 대한 피작동부의 면적비가 4.5인 조건에서도 정체실의 정상압력이 잘 형성됨을 알 수 있었다.

• 한국항공우주학회지
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• 제43권5호
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• pp.456-465
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• 2015

듀얼 벨 노즐은 일반적인 벨 형상 노즐의 문제점인 저고도에서의 과대팽창, 고고도에서의 과소팽창을 감소시키며, 이로 인해 손실되는 비추력을 최소화 할 수 있는 노즐이다. 미국의 Rocketdyne사에서는 확장 노즐의 형상에 따른 추력특성을 분석하였고, NASA에서는 고도에 따른 연소실험을 수행하였다. 유럽은 DLR을 중심으로 굴곡각, 노즐 길이, 팽창비 등에 따른 연구를 진행하고 있으며, 러시아의 MAI에서는 팽창부에 슬롯을 추가하여 추력손실을 줄일 수 있는 연구가 진행되고 있다. 아시아에서는 일본, 인도 등에서 연구가 진행되고 있고, 일본의 미쓰비시사에서 슬롯 노즐과 유사한 개념의 기술을 특허로 등록하였다. 본 논문에서는 고도 보정이 가능한 노즐로써 듀얼 벨 노즐의 개념 및 성능과 국외 연구 개발 현황을 정리하였다. 국내에서도 경제성 있는 우주개발을 위해 듀얼 벨 노즐에 대한 연구가 필요하다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.460-465
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• 2004

ESPR project started in 1999 with METI and NEDO support as five-years program in order to develop necessary technologies for the next-generation SST engine. In ESPR program, jet noise reduction technologies are focused as environmentally compatible technologies, which are critical to realize next-generation SST. In designing a lobed mixer nozzle which is a jet noise suppression system, there are many difficulties to understand the detailed flow phenomena occurred in the system because of its complexity. Large Eddy Simulation (LES) was applied to the lobed mixer nozzle flow analysis in ESPR project. The results demonstrated that LES approach was capable of predicting mixing characteristics of a complicated flow.