• 한국자동차공학회논문집
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• 제6권3호
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• pp.26-33
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• 1998

An experimental study has been conducted for the three-dimensional in-cylinder swirl flow under steady conditions. Velocity fields are measured by using an LDV at various valve lifts. Effects of geometry of inlet ports on swirl flows are investigated for standard and helical ports. Swirl distributions evaluated from velocity measurements are compared with those obtained from an impulse torque swirl meter. Results show that the helical port generates more intensive swirl than the standard one but it causes red- uction in air flow coefficient. At the lower valve lift, no significant difference is observ- ed in non-dimensional swirl values between two ports because of limited pre-swirl effect, while it becomes significant as the valve lift increases.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.107-108
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• 2013

An experimental study in the dual swirl burner was conducted to analyze the temperature characteristics in the combustion field. The dual swirl burner consists of a main swirling pre-mixed flame with tangential swirler surrounding a pilot which can stabilize a diffusion flame or a partially premixed flame with vane swirler depending on whether fuel is supplied at the exit plane or further upstream. The purpose of this study is to analyse experimentally the characterization of flame temperature in the reacting zone, specially, according to the various combustor diameters like 80mm, 100mm, 130mm and 150mm(O.D). As a result, the temperatures of combustion field were decreased as the diameter of combustor increased. Therefore, these results can be expected that the larger diameter of combustor tend to emit less NOx emission than the small combustor.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권3호
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• pp.414-430
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• 2013

This paper shows the study of preswirl duct as an effective energy saving devices that have been devised and reviewed to support the propeller performance, especially for the ship of VLCC with large block coefficients. From the bare hull wake measurements, typical upper/lower asymmetry of hull wake at the propeller disk was found. The 2 kinds of pre-swirl duct, Unconventional half circular duct and Conventional circular pre-swirl duct have been designed and reviewed to recover the loss of propeller running in that condition. The general function of the pre-swirl duct was set to work against this asymmetry of wake and generate pre-swirled flow into the propeller against the propeller rotating direction. The optimum self propulsion tests with various angle configurations were carried out and the best configuration was decided. Accordingly, cavitation test was carried out with best configuration of unconventional half circular duct. The blade surface and tip vortex cavitation behaved smoother when the duct was mounted. The hull pressure amplitudes reflected this difference, so the hull pressure amplitude with duct was smaller than that of without duct.

• 한국해양공학회지
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• 제26권3호
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• pp.1-5
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• 2012

A complex energy saving device has been developed for middle class vessels. The propulsive performance of the developed device is described through a model test. The pre-swirl stator, which recovers the rotational energy of the propeller slipstream, is a well-known energy saving device for large vessels. The pre-swirl stator for a large vessel is usually cast as a part of the stern frame and has a high cost. The manufacture of a cast stator for an existing vessel is almost impossible. The complex device that was developed can be fitted on astern frame by welding. The model tests show a 4-6% efficiency gain for middle class vessels with the developed appendages compared to those with bare hulls.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1134-1141
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• 2003

Performance of a gas turbine combustor installed in a test facility has been studied by measuring spatially- and temporally-resolved temperature distributions using multiplex CARS technique. 500 CARS temperatures were determined at each measuring point to obtain a histogram of temperature distribution. Experiments were carried out in the aero-engine combustor sector rig burning standard kerosene fuel. The histograms were obtained around a triple-sector double annular rig running in ground idle conditions, showing features of flow mixing within the rig. The temperature histograms that prove the existence of high temperatures above 1900 K provide us valuable information to improve the design of the combustor structure suppressing NOx generation in turbulent combustion processes. The effects of swirl direction and pre-filmer on gas turbine combustion were investigated. When we installed radial swirls, a large recirculation zone was formed by the fuel module regardless of swirl directions and the pre-filmer installation. It is found that the swirl direction affects the shape of the reverse flow zone, however. Also, an attempt to estimate the flow field and flame structure is made using the histogram of temperature determined with the CARS technique.

• 한국전산유체공학회지
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• 제12권3호
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• pp.8-12
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• 2007

An optimized bidet nozzle design to form the required swirl water jet is proposed with the help of numerical analysis. The bidet can do the cleaning process of human body by water injection and the speed/pressure/injection angle/magnitude of swirl intensity of water jet determine the cleaning capability and personal subjective feeling. The objective of this research is to design optimal water injection nozzle to make stable swirl intensity. The effect of individual design variables are analyzed from the basic design and the final design is deduced to make high performance water jet within the pre-determined operation conditions.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 춘계 학술대회논문집
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• pp.68-71
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• 2007

An optimized bidet nozzle design to form the required swirl water jet is proposed with the help of numerical analysis. The bidet can do the cleaning process of human body by water injection and the speed/pressure/injection angle/magnitude of swirl intensity of water jet determine the cleaning capability and personal subjective feeling. The objective of this research is to design optimal water injection nozzle to make stable swirl intensity. The effect of individual design variables are analyzed from the basic design and the final design is deduced to make high performance water jet within the pre-determined operation conditions.

• 한국항공우주학회지
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• 제47권12호
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• pp.881-889
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• 2019

가스터빈 이차 유로의 프리스월 시스템은 터빈의 효율을 높이고 소재의 수명을 연장하기 위해 설치되는 냉각 장치이다. 본 연구에서는 프리스월 시스템의 설계점을 기준으로 가스터빈 외기 온도와 터빈 부하 변화에 따른 탈설계점 분석을 수행하였다. 탈설계점에서 내부 유동의 특성을 분석하기 위하여 유량계수와 단열계수를 비교하였다. 터빈 부하 증가에 따라 시스템 내부 냉각 공기의 체적 유량이 증가하였고, 단열계수 또한 20% 터빈 부하와 비교하여 100% 터빈 부하에서 30.46% 상승하였다. 외기 온도가 증가할수록 질량 유량과 냉각 공기의 밀도는 감소하였지만 체적 유량은 상승하였으며, 결과적으로 프리스월 시스템 내부의 냉각 성능은 향상되었다. 프리스월 시스템 출구에서 -20℃ 외기 온도와 비교하여 55℃ 외기 온도의 단열계수는 14.82% 향상되었다.

• 대한조선학회논문집
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• 제59권3호
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• pp.141-148
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• 2022

A hybrid turbulence model has developed by combining a sub-grid scale model using dynamic k equation in LES with k-𝜔 SST model of RANS equation. To ascertain potential applicability of the hybrid turbulence model, fully developed turbulent channel flows at Re_𝜏=180 have been simulated of which computational domain has a top wall with coarse cells and a bottom wall with fine cells. The streamwise mean velocity and turbulent intensity profiles showed a good agreement with DNS data when using the hybrid model rather than using a single model in k-𝜔 SST or dynamic k equation models. Computational simulations of turbulent flows around KVLCC2 with a pre-swirl duct have been mainly performed using the hybrid turbulence model. Compared to the results obtained from RANS simulation with k-𝜔 SST model as well as LES with dynamic k equation SGS model, turbulent wakes of the duct in the present simulation using the hybrid turbulence model were very similar to that of LES. Also, the resistances acting on hull, rudder and duct in hybrid turbulence model were similar to those in RANS simulation whereas the viscous forces acting on the hull in LES had a significant error due to coarse cells inappropriate to the sub-grid scale model.

• 한국산업융합학회 논문집
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• 제1권2호
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• pp.49-54
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• 1998

In the catalytic combustor, combustion characteristic and deterioration of catalysts were affected by non-uniformity of pre-mixed gas, Therefore, formation of uniform pre-mixed gas is one of important subjects. In this study, the effect of uniformity and non-uniformity of pre-mixed gas supplied to the catalyst was examined to clarify reaction acceleration and combustion characteristic of the catalytic combustion. It was clarified that static mixer or vaporizer tube length of about 150mm and weak swirl to a combustion air were effictive expedient to make uniform pre-mixed gas. And catalystic inlet temperature needs more than $600^{\circ}C$ with rich pre-mixed gas to active reaction.