• Journal of Digital Convergence
• /
• v.10 no.5
• /
• pp.283-288
• /
• 2012

This study was undertaken to investigation the spray characteristics of the twin fluid atomization nozzle system. The light oil was injected at the normal temperature and injection pressure was 5 bar - 10 bar by 1 bar and volume flow was 0.5, 1.0 and 2,0 mmH2O(X10-2). We measured the SMD of sprayed droplet to study spray characteristics. The following conclusions were reached from the results of these study. 1. The more injection pressure increased, the more SMD decreased. 2. The more measuring distance between pressure nozzle tip and analyser beam increased, the more SMD increased. 3. SMD of the blower-air-added injection system were shown, increasing volume flow decreased respectively. The result of this study indicated the blower-air-added injection system induced beneficial changes in SMD. And it will be considered important indicator for spray characteristics design and performance evaluation of twin fluid atomization nozzle system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.687-692
• /
• 2016

When turbochargers are applied to engines, the temperature of the engine becomes high, making the cooling of pistons very important. To solve this problem, an oil jet is used. The oil jet provides oil to the underside of piston for cooling. When an oil jet is used, oil pump size-up and oil cooler are needed because of the increased oil flow rate and higher oil temperature. On the other hand, these increase the friction torque of the engine. This study examined how much the friction torque of an engine increases by an oil jet, oil cooler, and oil pump size-up. In addition, the proportions of the friction torque of the engine increased by each part were measured by changing the engine assembly condition. At low speed, the oil pump and oil cooler had a larger effect on the friction torque than the other factors. At high speed, oil cooler had a larger effect than the other factors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.299-304
• /
• 2005

The design procedures of full-scale combustion chamber with chamber pressure of 53bara, mass flow rate of 90kg/s, combustion efficiency of $94\%$ and specific impulse at ground of 253sec were described. The details of combustion performance and geometrical parameters were also given. Full-scale combustion chamber consists of the combustor head with injector/baffle and the chamber/nozzle with regenerative cooling channels. The design results of combustion chamber with ablative materials, detachable injector head with SUS baffle or baffle injector and chamber body for ground hot firing tests were given in this paper.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.3
• /
• pp.37-43
• /
• 2004

Water-jet trajectory visualization and velocity deficits from a high pressurized steam-generator nozzles were experimentally observed. In order to find an optimal nozzle configuration. several parameters affecting plugging and erosion onto the steam generator tube were quantitatively analyzed. For the experiments, a high-pressurized pump (pressure in use: 200 kg/$\textrm{cm}^2$, 15 HP, 11 kW, output flow Q : 301/min) was utilized. Visualization, velocity distribution, and spray growth rate with different nozzle configurations have been mainly focused using a 2-D PDPA system. The results indicated that trajectories along the centerline regardless of their configurations has its potential core region. However, the phenomena from the peripheral part need to be meticulously considered. Accordingly, it is evident that quantitative velocity deficits at the outer region are outstanding due to the aerodynamical drag and entrainment.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.20 no.6
• /
• pp.107-116
• /
• 2012

In this study, the trucks(2.9-liter) have been developed to use DME as fuel, and performance test of the vehicle's DME engine, power, emissions, fuel economy and vehicle aspects was conducted. For experiments, the fuel system(common-rail injectors and high-pressure pump included) and the engine control logic was developed, and ECU mapping was performed. As a result, the rail pressure from 40MPa to approximately 65% increase compared to the base injector has been confirmed that. Also, the pump discharge flow is 15.5 kg/h when the fuel rail pressure is 400rpm(40MPa), and the pump discharge flow is 92.1 kg/h when the fuel rail pressure is 2,000rpm(40MPa). The maximum value of full-load torque capability is 25.5 kgfm(based on 2,000 rpm), and more than 90% compared to the level of the diesel engine were obtained. The DME vehicle was developed in this study, 120 km/h can drive to the stable, and calculated in accordance with the carbon-balance method of fuel consumptions is 5.7 km/L.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.7
• /
• pp.2267-2276
• /
• 1996

Twin-fluid atomization has been widely used in combustors and process industries because of its high performance and simple structure. Flow visualization and pressure measurements were conducted to investigate the effects of gas flow in twin-fluid atomization. Schlieren photographs showed that changes in atomizing gas pressure, altered the wave patterns, and the lengths of both recitrculating toroid (impinging stangnation point) nad supersonic flow region in the jet. A longer supersonic wave pattern like net-shape wqas observed as atomizing gas pressure increased. The disintegration phenomenon of liquid delivery tube. The variation of spray angles with gas pressures were obtained by visualization using laser sheet beam. Suction pressuresat the nozzle orifice exit and recirculating region are shown to be used to estimate the stable atomization condition of a twin-fluid atomizer.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.482-482
• /
• 2013

반도체 소자의 미세화와 더불어 세정공정의 중요성이 차지하는 비중이 점점 커지고, 이에 따라 세정 기술 개발에 대한 요구가 증대되고 있다. 기존 세정 기술은 화학약품 위주의 습식 세정 방식으로 표면 손상, 화학 반응, 부산물, 세정 효율 등 여러 가지 어려움이 있다. 따라서 건식세정 방식이 활발하게 도입되고 있으며 대표적인 것이 에어로졸 세정이다. 에어로졸 세정은 기체상의 작동기체를 이용하여 에어로졸을 형성하고 표면 오염물질과 직접 물리적 충돌을 함으로써 세정한다. 하지만 이 또한 생성되는 에어로졸 내 발생 입자로 인해 패턴 손상이 발생하며 이러한 문제점을 극복하기 위하여 본 연구에서는 가스클러스터 장치를 이용한 세정 특성 평가에 관한 연구를 수행하였다. 가스 클러스터란 작동기체의 분자가 수십에서 수백 개 뭉쳐 있는 형태를 뜻하며 이렇게 형성된 클러스터는 수 nm 크기를 형성하게 된다. 그리고 짧은 시간의 응축에 의해 수십 nm 크기까지 성장하게 된다. 에어로졸 세정과 다르게 클러스터가 성장할 환경과 시간을 형성하지 않음으로써 작은 클러스터를 형성하게 되며 이로 인해 패턴 손상을 최소화 하고 상대적으로 높은 효율로 오염입자를 제거하게 된다. 클러스터 세정 장비를 이용한 표면 처리는 충돌에 의한 제거에 기반한다. 따라서 생성 및 가속되는 클러스터로부터 대상으로 전달되는 운동량의 정도가 세정 특성에 영향을 미치며 이는 생성되는 클러스터의 크기에 종속적이다. 생성 클러스터의 크기 분포는 분사 거리, 유량, 분사 각도, 노즐 냉각 온도 등의 변수에 관한 함수이다. 따라서 본 연구에서는 $CO_2$ 클러스터를 이용한 세정 특성을 평가하기 위하여 이러한 변수에 따라서 오염 입자의 종류, 크기에 따른 PRE (particle removal efficiency)를 평가하고 다양한 선폭의 패턴을 이용하여 손상 실험을 수행하였다. 제거 효율에 사용된 입자는 $CeO_2$와 $SiO_2$이며, 각각 30, 50, 100, 300 nm 크기를 정량적으로 오염시킨 쿠폰 웨이퍼를 제조하여 세정 효율을 평가하였다. 정량적 오염에는 SMPS (scanning mobility particle sizer)를 이용한 크기 분류와 정전기적 입자 부착 시스템이 사용되었다. 또한 패턴 붕괴 평가에는 35~180 nm 선폭을 가지는 Poly-Si 패턴을 이용하였다. 실험 결과 클러스터 형성 조건에 따라 상대적으로 낮은 패턴 붕괴에서 95% 이상의 높은 오염입자 제거효율을 전반적으로 보이는 것을 확인할 수 있었다. 따라서 이론적 계산에 기반하여 세정에 요구되는 클러스터 크기를 가정하고, 이를 통하여 세정에 적용할 경우 높은 기존 세정 방법의 단점을 보완하면서 높은 세정 효율을 가지는 대체 세정 방안으로 이용할 수 있음을 확인하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.133-137
• /
• 2008

Results of combustion tests performed for a regenerative cooling combustor of a 30 tonf-class liquid rocket engine were described. The combustion chamber has chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion of 12. The combustion chamber is composed of mixing head, baffle injector, and regenerative cooling chamber. The hot firing tests were performed at design and off-design points. The test results show that the combustion characteristic velocity is in the range of 1738${\sim}$1751 m/sec and the specific impulse of the combustion chamber is in the range of 253${\sim}$270 sec. The peak of combustion characteristic velocity and specific impulse for this combustor is shown at mixture ratio of 2.35 and 2.5, respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.139-143
• /
• 2007

The overall results of combustion tests performed for a 30 tonf-class full-scale combustion chambers of a liquid rocket engine were described. The combustion chambers have chamber pressure of 53${\sim}$60 bar and propellant mass flow rate of 89 kg/so The combustion chamber is composed of mixing head, SUS baffle, baffle injector, ablative chamber, channel cooling chamber and regenerative cooling chamber. The test results show that the combustion characteristic velocity is in the range of 1673${\sim}$1730 m/sec and the specific impulse of the combustion chamber is in the range of 254${\sim}$263 sec. As the recess number of the injectors increases, the combustion characteristic velocity increases. And as the combustion characteristic velocity increases, the specific impulse of the combustion chamber also increases.

• Journal of ILASS-Korea
• /
• v.25 no.1
• /
• pp.8-14
• /
• 2020

Recently, 1-D model-based engine development using virtual engine system is getting more attention than experimental-based engine development due to the advantages in time and cost. Injection rate profile is the one of the main parameters that determine the start and end of combustion. Therefore, it is essential to set up a sophisticated model to accurately predict the injection rate as starting point of virtual engine system. In this research, procedure of 1-D model setup based on AMESim is introduced to predict the dynamic behavior and injection rate of diesel injector. As a first step, detailed 3D cross-sectional drawing of the injector was achieved, which can be done with help of precision measurement system. Then an approximate AMESim model was provided based on the 3D drawing, which is composed of three part such as solenoid part, control chamber part and needle and nozzle orifice part. However, validation results in terms of total injection quantity showed some errors over the acceptable level. Therefore, experimental work including needle movement visualization, solenoid part analysis and flow characteristics of injector part was performed together to provide more accuracy of 1-D model. Finally, 1-D model with the accuracy of less than 10% of error compared with experimental result in terms of injection quantity and injection rate shape under normal temperature and single injection condition was established. Further work considering fuel temperature and multiple injection will be performed.