• 한국자동차공학회논문집
• /
• 제5권5호
• /
• pp.178-187
• /
• 1997

For the experimental measurement of heat flux of DI diesel engine combustion chamber, the instantaneous temperature probes and data acquisition system were developed. By the analysis of measured temperatures at the cylinder head, the temperature at the point 3 which is located between intake and exhaust valve was higher than that of the other points. Temperatures at the point located mear the exhaust valve were higher than those of intake valve. The instantaneous and mean temperature at the cylinder head increases proportionally to the increase of the engine speed, while the temperature swing varies inversely. Temperature swings have influence on the maximum heat flux values from gas into head surface. It has been verified that these probes and data acquisition system perform well by the comparison of the trend of instantaneous temperature variation with that of measured combustion chamber pressure variation with respect to crank angle. It is presumed that these probes could be used in the measurement of other parts of combustion chamber as piston, cylinder wall etc. for the future study.

• Journal of Advanced Marine Engineering and Technology
• /
• 제38권10호
• /
• pp.1263-1268
• /
• 2014

In this study, the variations of swirl center according to evaluating position have been investigated in a steady flow bench of SI engine. For the experiments, two engine heads with different intake valve angles ($11^{\circ}$ and $26^{\circ}$) were tested in the flow bench by varying the evaluating position (1.75~6.0B) and valve lift (2~10 mm). Particle image velocimetry was used to measure the velocity field inside the engine cylinder. The swirl center position is found with a critical point theory and the intensity of turbulence is calculated from PIV velocity data. The results show that the center of swirl is located closer to the center of cylinder and turbulence intensity is lower, when the intake valve angle is the smaller. It is conventional to evaluate the swirl ratio at 1.75B position in the steady flow bench of SI engine. At this position, however, the distance of swirl center from the cylinder center scatters significantly for the variation of valve lift, and the turbulence intensity is much stronger regardless of the valve angle. Thus, to estimate the flow at the end of compression stroke in a real engine from the data in the steady flow experiments, the evaluation position should be moved further downstream more than 4.5B.

• 한국자동차공학회논문집
• /
• 제3권5호
• /
• pp.82-89
• /
• 1995

The three-dimensional fluid motion through the intake port and cylinder of a single DOHC SI engine was investigated with a commercial computational fluid dynamics simulation program, STAR-CD. This domain includes the intake port, intake valves and combustion chamber. Steady induction port flows for various valve lifts have been simulated for an actual engine configuration. The geometry was obtained by direct interface with a three-dimensional CAD software for complicated port and valve shape. The computational grid was generated using the commercial preprocessor ICEM CFD/CAE. Detailed procedures were presented on the generation of the geometry and the block-structured mesh. A standard k-${\varepsilon}$ turbulent model was applied to consider the complexity of the geometry and the fluid motion. The global flow patterns and the distributions of various quantities, such as pressure, velocity magnitude around the valve seat etc., were examined. The computational results, such as mass flow rate, discharge coefficient etc., for various valve lifts were compard with the experimental results and the computational results were found in good agreement with the experiment.

• 한국가스학회지
• /
• 제11권2호통권35호
• /
• pp.37-42
• /
• 2007

본 논문에서는 밸브몸체와 밸브스템 사이의 사각그루브에 설치한 두 개의 O-링에 대한 누설 안전성을 해석한 결과를 제시하고 있다. O-링시일의 누설 안전성에 대한 해석은 압축률과 LPG 가스압력의 변동에 따라 발생되는 누설 안전성을 유한요소해석 프로그램 MARC로 계산하였다. FEM 해석결과에 따르면, LP가스 충전압력 $8kg/cm^2$에서 안전변의 안전한 작동압력 상한치 $24.8kg/cm^2$에 이르기까지 압력하중을 압력용기 안전기준에 의거 계산한 결과는 안전한 것으로 나타났다. 다만, 두 개의 O-링의 안전성을 충분하게 확보하기 위해서는 O-링소재의 시효경화 효과를 고려하는 것이 바람직하다.

• 대한기계학회논문집B
• /
• 제21권5호
• /
• pp.650-658
• /
• 1997

Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.

• 한국가스학회지
• /
• 제22권2호
• /
• pp.72-77
• /
• 2018

본 연구에서는 볼밸브와 긴 실린더 튜브로 구성된 LPG 충전장치의 강도안전성에 대한 FEM 해석결과를 제시하고 있다. LPG 충전장치의 강도안전성 해석을 위해 1.7~3.5mm의 벽면 두께를 갖는 볼밸브와 긴 실린더 튜브에 0.5~3.5MPa의 가스압력을 공급하였다. 1.7mm 벽면 두께를 갖는 볼밸브에 3.5MPa의 가스압력을 공급하였을 때 발생한 von Mises 최대응력은 25.4MPa이고, 이 값은 황동소재 항복강도의 25.9%에 해당한다. 그리고 1.7mm 벽면 두께를 갖는 긴 실린더 튜브에 3.5MPa의 가스압력을 공급하였을 때 발생한 von Mises 최대응력은 23.7MPa이고, 이 값은 동일한 조건으로 해석한 볼밸브에 비해 6.7%나 더 안전한 것으로 나타났다. 긴 실린더 튜브의 벽면 두께를 2.0mm로 증가시켰을 경우 발생한 von Mises 최대응력 20.2MPa은 1.7mm의 벽면 두께를 갖는 같은 실린더 튜브에 비해 14.8%나 더 안전하였다. 따라서 본 연구에서는 볼밸브와 실린더 튜브의 강도안전성을 확보하기 위해서는 벽면의 두께를 1.7~2.0mm 정도로 최적화된 LPG 충전장치가 바람직하다.

• 한국가스학회지
• /
• 제18권6호
• /
• pp.27-31
• /
• 2014

본 연구에서는 LP가스 용기용 밸브에서 취약할 것으로 예상되는 Part 1, Part 2, Part 3 지역에 대한 강도안전성을 FEM으로 해석하였다. 밸브의 두께가 1.5mm이고, LPG 압력이 3.5MPa일 때 밸브의 Part 1 모서리 부분에서 27.5MPa의 Von Mises 최대응력이 걸리는 것으로 나타났다. 또한, 밸브의 두께가 1.5mm이고, LPG 압력 3.5MPa이 밸브에 작용할 때 Von Mises 최대응력은 Part 2에서 41.5MPa, 그리고 Part 3에서 46.5MPa으로 나타났다. 이러한 FEM 해석결과는 밸브의 Part 1, Part 2, Part 3에 작용하는 Von Mises 최대응력 모두가 황동소재 C3604의 항복강도 대비 9.2~15.5% 수준으로 대단히 낮은 값을 나타내고 있다. 이것은 기존의 LP가스 용기용 밸브의 두께가 지나치게 과도한 설계를 하였다는 것을 의미한다. 따라서, 밸브의 Part 1과 Part 2 지역의 두께는 황동밸브의 경량화 차원에서 얇게 설계하는 것이 바람직하다. 반면에 Part 3 지역의 두께는 기존의 밸브 두께처럼 두껍게 설계하여 높은 체결토크에도 안전한 강도를 유지하는 것이 좋다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.790-795
• /
• 2001

Since the characteristics of combustion and pollutant in Diesel engines were mainly affected by the characteristics of in-cylinder gas flow and fuel spray, an understanding of those was essential to the design of the D.I. Diesel engines. The improvement of volumetric efficiency of air charging into combustion chamber is a primary requirement to obtain better mean effective pressure of an engine. Since the air resistances in intake and exhaust flow passages, valve lift and valve shape influence greatly to the volumetric efficiency, it is very important to investigate the flow characteristics of intake and exhaust port which develops air motion in the combustion chamber. This paper presents the results of an experimental investigation of steady flow through the various kinds of commercial cylinder head ports, and the development procedures of HHI's H21/32 prototype cylinder head ports.

• 유공압시스템학회논문집
• /
• 제3권1호
• /
• pp.1-6
• /
• 2006

A servo actuator with a valve using MR (Magneto-Rheological) fluid is proposed for fluid control systems. The MR fluid is well known as a functional fluid whose apparent viscosity is controlled by the applied magnetic field strength. The pressure in the MR cylinder can be controlled by the applied magnetic field strength. Good points of the MR cylinder are more simple, compact and reliable structure than a conventional oil hydraulic cylinder. The experimental results show that the MR cylinder could be used as a servo actuator.

• 한국수소및신에너지학회논문집
• /
• 제19권3호
• /
• pp.182-188
• /
• 2008

In order to improve scavenging performance of free piston hydrogen fueled engine, this study estimate compatibility of uni-flow scavenging. The scavenging flow characteristics in the cylinder is investigated by flow visualization and PIV method. Consequently it has been found that the scavenging performance decreased with abnormal expansion of piston and delay of the exhaust valve opening timing. And the scavenging performance of exhaust valve located center in cylinder head is better than that of exhaust valve located side in cylinder head.