• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.714-719
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• 2007

In this paper, we report experimental investigations on measurement of adiabatic wall temperature on a flat 2-D plate of high-speed impinging jet made by circular-shape nozzle at steady state condition using infra-red camera. Experiments have been conducted for the Reynolds number of 187,000 according to the change of nozzle-to-plate distance. Dimensionless number, recovery factor, has been used to represent the measured adiabatic wall temperature. And we compared the result obtained by using infra-red camera with that obtained by using thermocouple.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.751-757
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• 2001

An experimental study of impinging jet-flow structure has been carried out for a fully developed single circular jet impingement cooling on a flat plate, and the effect of the wall thickness at nozzle exit edge is investigated. Impinging jet flow structures have been measured by Laser-Doppler Velocimeter to interpret the heat transfer results presented previously by Yoon et al.(sup)(10) The peaks of heat transfer rate are observed near the nozzle edge owing to the radial acceleration of jet flow when the nozzle locates close to the impingement plate. The growth of the velocity fluctuations in the wall jet flow is induced by the vortices which originate in the jet shear layer, and consequently the radial distribution of local Nusselt numbers has a secondary peak at the certain radial position. As a wall of circular pipe nozzle becomes thicker for small nozzle-to-target distance, the entrainment can be inhibited, consequently, the acceleration of wall jet flow is reduced and the heat transfer rate decreases.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.74-83
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• 2003

In the advanced nuclear power plants including APR1400, the SDVS (Safety Depressurization and Vent System) is adopted to increase the plant safety using the concept of feed-and-bleed operation. In the case of the TLOFW (Total Loss of Feedwater), the POSRV (Power Operated Safety Relief Value) located at the top of the pressurizer is expected to open due to the pressurization of the reactor coolant system and discharges steam and/or water mixture into the water pool, where the mixture is condensed. During the condensation of the mixture, thermal-hydraulic loads such as pressure and temperature variations are induced to the pool structure. For the pool structure design, such thermal-hydraulic aspects should be considered. Understanding the phenomena of the submerged steam jet condensation in a water pool is helpful for system designers to design proper pool structure, sparger, and supports etc. This paper reviews and evaluates the steam jet condensation in a water pool on the physical phenomena of the steam condensation including condensation regime map, heat transfer coefficient, steam plume, steam jet condensation load, and steam jet induced flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.325-329
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• 2017

In this study, the combustion experiment of hydrocarbon-kerosene fueled dual mode ramjet combustor was performed at mach number 3.5~6.0 conditions. Through the experiment, the temperature and the pressure distribution inside the combustion chamber were measured and the combustion characteristics inside the combustion chamber were investigated. In the mach number 3.5~5.0 range, it was able to identify subsonic combustion in the downstream combustion chamber. In the mach number 6.0 condition, the injected fuel from the injectors was naturally fired, and it was possible to confirm that supersonic combustion was successful in the upper chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.133-138
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• 2012

Exhaust facility has basically the role of flame deflector, and considering additional functions, it can be classified by noise/emission suppressor and altitude simulation facility. In this paper, principles of flame deflector, jet pump, emission suppression are presented for exhaust treatment facility. Principles of noise suppression caused by Mach wave mitigation, jet energy mitigation by water evaporation and condensation are shown. In addition, a concept of vertical exhaust treatment facility is presented applying basic principles aforementioned.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.536-540
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• 2018

As the performance of engines improves, the temperature of engines is increasing, resulting in a high piston temperature. An excessively high piston temperature may result in torque drop or engine failure. An oil jet is used to reduce the piston temperature. In this study, to monitor the effect of oil jet, a templug was used to measure the piston temperature. A templug is a kind of sensor and the hardness of the templug changes according to the piston temperature. Using a templug, the maximum temperature of the piston was measured with and without an oil jet. The piston temperature was lowered using the oil jet. The highest temperature region changed from the center crown to the front/rear area. In addition, the temperature difference between the highest and lowest regions became smaller.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.139-145
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• 2002

The flow zone through propeller jets are used in evaluating the environmental and constructional effects of navigation on the waterway. It relies on the characteristics of ships and water depth. A numerical model using the momentum theory of the propeller and Shield's diagram was developed in a restricted waterway. Equations for discharge are presented based on thrust coefficients and propeller speed and are the most accurate means of defining discharge. Approximate methods for discharge are developed based on applied ship's power. Equations for discharge are as a function of applied power, propeller diameter, and ship speed. Water depth of the waterway and draft of the shop are also necessary for the calculation of the grain size of the initial motion. The velocity distribution of discharge from the propeller was simulated by the Gaussian normal distribution function. The shear velocity and shear stress were from the Sternberg's formula. Case studies to show the influence of significant factors on sediment movement induced by the ship's propeller at the channel bottom are presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.86-94
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• 2013

Research on dynamic characteristics of injectors gives us insight for preventing combustion instability in a rocket engine. While lots of studies have been done about swirl injectors' dynamic characteristics, little is known about impinging jet injectors' dynamic characteristics. For this reason, this study was aimed to reveal the dynamic characteristics of an impinging jet injector based on experiment using a hydraulic mechanical pulsator. Gain, which is the relationship between input pressure and output value(pressure or velocity) was analyzed with the frequency and manifold pressure change. Pulsating frequency was chosen in the low range: 5, 10, 15 Hz. As a background work, Methods to determine the jet velocity were discussed. Klystron effect was also considered as a factor of this experiment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.15-15
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• 1998

마하 수 6 이상인 극초음속 비행에는 스크램제트(SCRamjet : Supersonic Combustion Ramjet) 엔진이 가장 적합한 엔진으로 알려져 있고 현재 미국을 중심으로 이 엔진의 개발에 많은 노력을 기울이고 있다. 스크램제트 엔진의 성공적인 개발을 위해서는 초음속 공기 내에서 연료의 분사를 통한 가장 효율적인 연소를 유도할 수 있어야 한다. 초음속 상태의 공기와 연료의 혼합을 증대시키고 연소안정성을 향상시키는 방법으로 연소기 내에 인위적으로 경사충격파를 발생시키는 방안이 Marble 등에 의해 최초로 도입되었다. 본 연구에서는 스크램제트엔진 내의 연소기를 모델링하여 마하수 2.5의 초음속공기 유동 중앙에 수소 제트를 분사하여 초음속 수소-공기 화염을 만들고 연소기의 측면에 동일한 모양과 크기의 쐐기를 각각 부착시켜 평면 경사충격파를 발생시켰다 본 실험은 충격파가 초음속 화염에 미치는 영향을 연구한 최초의 실험연구이다.

• Journal of ILASS-Korea
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• v.11 no.2
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• pp.113-120
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• 2006

The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic cross flows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory and width of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.