• Journal of the korean Society of Automotive Engineers
• /
• v.10 no.4
• /
• pp.14-18
• /
• 1988

액체의 미립화는 액체연료의 연소를 위한 분무, 분무 도장, 농약 살포, 의료기기, 용융 금속의 금속 분말의 제조 등의 여러분야에 널리 이용되고 있다. 특히 연소 기관은 액체 연료의 미립화와 증발 특성에 따라 기관의 연소와 성능은 크게 변화하므로 연소실 내의 연료 미립화 특성의 개선은 매우 중요하다. 미립화에 영향을 미치는 인자에는 연료의 물성과 분사 기구 및 분사 밸브 등의 구조와 분사압력 등은 연료 미립화에 주된 영향을 미치는 요인의 하나가 되고 있다. 여기서는 주로 액체연료의 미립화에 일반적인 기초 사항과 분무 특성의 표시 방법, 측정법에 대하여 기술하기로 한다.

• Fire Science and Engineering
• /
• v.33 no.5
• /
• pp.28-36
• /
• 2019

In the present study, the effects of supply gas and water mist on the heptane pool fire extinguishing performance were investigated using the full cone and hollow cone twin-fluid atomizers. Air or nitrogen of 30 lpm (Liter per minute; L/min) was used as the supply gas, and the experiments were conducted under the water flow rate conditions of 0 lpm (i.e., discharge of air or nitrogen only) and 0.085 lpm (i.e., discharge of water mist with supply gas). Experimental results confirmed that the use of water mist discharge with the supply gas and full cone spray pattern reduced the fire extinguishing time as compared to that of only supply gas discharge and hollow cone spray pattern. In addition, for the discharge of water mist using the full cone twin-fluid atomizer, water mist significantly affected fire extinguishing performance, whereas the effect of the supply gas was less pronounced. On the other hand, for the discharge of water mist using the hollow cone twin-fluid atomizer, the fire extinguishing time was remarkably reduced by the supply of nitrogen, as compared with that of air, indicating that the supply gas as well as water mist can significantly affect fire extinguishing performance.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.270-275
• /
• 2016

The characteristics of the fuel quantity, injection rate and macro spray development was investigated under a range of diesel fuel temperatures. The actual injection quantity decreased despite the same signal of the injection start and injection duration as the fuel temperature decreased. The injection rate measurements confirmed that the actual injection commencement was delayed and the actual injection duration was shortened under lower fuel temperature conditions, which explains why the injection quantity decreased. Spray tip penetration with a lower fuel temperature was longer than that with a higher fuel temperature due to the deteriorated atomization. As a pre-test for the combustion experiment under low temperature conditions, piston targeting with pilot injection was accomplished, which showed that the fuel droplet from pilot injection was introduced into the crevice area. This suggests that the pilot injection quantity and timing should be chosen with careful consideration for actual applications.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.12
• /
• pp.68-75
• /
• 2005

The effects of the physical properties of primary flow on the performance of a supersonic ejector were investigated. Axisymmetric annular injection type supersonic ejector was used for the study of the effects of molecular weight and the specific heat at constant pressure on the ejection performance. Test gases include; air, $CO_{2}$, Ar, $C_{3}H_{8}$, and $CCl_{2}F_{2}$ for different values of gas properties. As the molecular weight and CP of the primary gas increase, the secondary flow pressure increases at the same primary stagnation pressure and this behavior results from the combined effects of molar specific heat or specific heat ratio.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.4
• /
• pp.10-18
• /
• 2007

A tested micro axial-type turbine consists of two stages and its mean radius of rotor flow passage is 8.4 mm. This turbine could be applied to a driver of micro power system, and its rotational speed in the unloaded state reaches to 100,000 RPM. The performance of this system is sensitive depending on the blade angles of the rotor and stator because it is operated in a low partial admission rate, so a performance test is conducted through measuring the specific output power and the net specific output torque with various blade angles on the nozzle, stator and rotor. The experimental results show that the net specific output torque is varied by 15% by changing the rotor blade angle, and the optimal incidence angle is about $10.3^{\circ}$.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.6
• /
• pp.474-481
• /
• 2008

수소 기관에서 역화없이 고성능과 저$NO_x$를 실현시키기 위하여 밸브 타이밍 변화에 따른 흡기관 분사식 수소 기관의 성능을 파악하고 가솔린의 경우와 비교하였다. 그 결과 흡기밸브 타이밍은 역화억제와 성능향상에 큰 영향을 미치는 것을 확인하였다. 흡기밸브타이밍의 진각은 역화를 억제하며 효율과 출력을 동시에 향상된다. 비록 흡기밸브 타이밍 변화에 의해 NOx는 증가하지만, 희박영역인 출 ${\Phi}=0.5$에서 현저히 감소된다. 또한 열효율은 ${\Phi}=0.5$ 토크는 ${\Phi}=1.0$에서 가장 높게 나타난다. 흡기밸브 타이밍을 $ATDC20^{\circ}$에서 TDC로 변화시켰을 때, ${\Phi}=1.0$에서 토크는 약 28% 증가되고, ${\Phi}=0.5$에서 효율은 약 7%향상된다.

• Transactions of the Korean hydrogen and new energy society
• /
• v.18 no.1
• /
• pp.67-74
• /
• 2007

고효율의 실현이 가능한 흡기관 분사식 수소기관의 역화 억제 가능성을 파악하고자 밸브 오버랩 기간의 변화에 따른 제반 기관성능과 역화가 발생되는 역화한계 당량비를 실험적으로 해석하였다. 실험에는 기계식 연속 가변밸브 타이밍 시스템이 부착된 연구용 수소기관을 사용하였다. 밸브 오버랩기간은 배기밸브 개폐시기를 고정하고 흡기밸브 캠의 위상각을 조절하여 변화시켰다. 해석결과 밸브 오버랩 기간의 감소에 따른 제반기관성능은 통상의 기관과 유사하지만 역화한계 당량비가 확장되어 초기 단계이지만 수소기관의 역화발생에 밸브오버랩 기간이 관여하는 것이 보였다. 기관 회전수 1600 rpm, WOT의 실험 조건에서 밸브 오버랩 기간을 $20^{\circ}CA$에서 $0^{\circ}CA$로 감소시킨 경우 역화한계당량비는 약 45% 정도 확장되고 정미 토크는 16% 감소했다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.237-242
• /
• 2005

The energy consumed by compressor in gas turbine is equivalent to $30\sim50\%$ of energy produced by turbine and, therefore, research on reducing compression work is important in increasing the efficiency of gas turbine. One of the method to reduce the compression work is to inject small water droplets into the compressor. This method decreases the compression work by decreasing the compressor exit temperature through the evaporation of water. Researches on wet compression, up to now, are focused on thermodynamic analysis of wet compression where the decrease of exit flow temperature and compression work is demonstrated. This paper presents an thermodynamic and aerodynamic analysis of wet compression in centrifugal compressor for microturbine.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.2
• /
• pp.80-86
• /
• 1997

This experiment was undertaken to investigate spray characteristics of the conventional injection system and the ultrasonic energy added injection system. Sauter mean diameter was measured under the variation of injection pressure and the spray distance. To measure the droplet size, we used the Malvern system 2600C. The spray angle and mass distribution were analyzed to the CCD camera and the patternater. After experiment, it was found that the ultrasonic energy added injection system had smaller Sauter mean diameter of droplet, wider mass distribution and wider spray angle than the conventional injection system had.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.3
• /
• pp.1030-1043
• /
• 1991

본 연구에서는 모델링오차나 외란 등의 불확실성에도 강인한 슬라이딩 모드 제어방법을 이용하여 새로운 연료분사 제어기를 설계하였다. 그리고 8253 타이머와 A/D 변환기, 인터페이스회로 등으로 MPI가솔린 엔진용 전자 제어장치를 실제 엔진에 적용시킴으로써 새로이 설계된 연료분사 제어시스템의 성능을 파악하였다.엔진의 운전상태를 여러가지 제어 모드로 분류할 수 있으나 엔진회전수가 2000rpm, 부하가 20N의 일정한 부하 조건에서 엔진회전수를 1500rpm에서 2000rpm으로 변화시켰을 때의 과도상태 응답을 파악하였다. 이와 같이 새로운 슬라이딩 모드 연료분사 제어시스템 을 개발하여 3원촉매 변환기의 변환효율을 극대화함으로써 배기가스의 유해물질을 최 소화하는 것을 본 연구의 목적으로 하였다.