• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.5
• /
• pp.86-95
• /
• 2000

A modified spray impingement model has been developed, which is assessed against experiments for the impinging sprays on the small combustion chamber at various gas pressures. To investigate spray behaviors in the diesel combustion chamber, a transparent constant-volume chamber is made which is similar to the combustion chamber of the real diesel engine. The chamber is pressurized by N2 gas from 0 bar to 20 bar to find the effects of ambient pressures. The behaviors of spray injected into this chamber and dispersed after impingement on the cylinder wall is measured two-dimensionally using laser sheet Mie scattering method. The physical submodels have been properly modified to improve the prediction capability of original KIVA code to describe the spray behaviors after impingement on the curved cylinder wall. In terms of spray dynamics and evolution. numerical results give qualitatively good agreements with experimental data.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.2
• /
• pp.195-201
• /
• 1997

Static and non-static flame methods were used to measure the laminar burning velocity of methane, ethane and natural gas. The flame slot angle and velocity of unburned gas mixture were determined by Schlieren method and LDV, respectively, for static flame. The diameter of nozzle was selected as 11 mm. The experimental results containing the stretch effect showed that the maximum burning velocities were 41.5 for natural gas, 40.8 for methane and 43.4 cm/sec for ethane on equivalence ratio of 1.1. Constant volume combustion chamber was also used for non-static flame. The propagation process of flame front was visualized by high speed camera during constant pressure. The maximum burning velocity of natural gas was determined as 42.1 cm/sec on equivalence ratio of 1.15.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.10
• /
• pp.1311-1317
• /
• 2001

To investigate only the effects of the stratified mixture distribution on initial flame propagation and combustion characteristics, the instantaneous equivalence ratio in the spark plug gap and combustion pressure were measured simultaneously In a constant volume chamber, To induce the stratified propane-air mixture distribution near the spark plug, counter-flow typed mixture injection system was used under the constant mean equivalence ratio $\Phi$$\_$mean/= 1.0 The instantaneous equivalence ratio was measured by a single-shot Raman scattering with narrow-band KrF excimer laser. The measuring error was within the limit of $\pm$ 3.5% provided that the proposed method was applied to the measured Raman signals. Judging from mass fraction burned derived from the measured pressure, the optimum combustion characteristics were shown under the condition that the local equivalence ratio in the spark plug was near 1.28$\pm$0.04, and these characteristics were more remarkable at the initial stage of combustion.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.317-323
• /
• 1987

A pressure tracking control of hydroforming processes, which is used in the precision forming of. sheet metals, is considered in this paper. The hydroforming of sheet metal is performed between the high-pressure chamber controlled by pressure control valve and the punch moving with constant speed. Since the pressure in the forming chamber is a critical factor to the quality of the product severely. It is important to control the pressure to follow a prescribed pressure trajectory, depending upon the material volume and shape of the parts to be formed. Taking into consideration of the volume chamge of forming chamber during the process and the nonlinearity of the electro-magnetic relief valve, a mathematical formulation of the model describing the dynamic characteristics of this model obtained. Based upon this model a PID controller is designed for the pressure tracking.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.1
• /
• pp.121-130
• /
• 1999

It is necessary to measure pressure, temperature, chemical equilibrium and the shape of flame in order to understand the combustion process in a combustion chamber. In particular, the flame formulation and combustion process of divided combustion chamber are different from those of a single chamber, And the variable diameter of a jet hole can effect not only physical properties like ejection velocity, temperature and time of combustion but also a chemical property like the reaction mechanism. Accordingly temperature is one of the most important factors which influence the combustion mechanism. This paper observed shape of flame by using the schlieren photographs and measured the pressure in a combustion chamber and the reaching time of the flame by ion probe By doing these, we investigation the formulation of the flame and the process of propagation. These measurement methods can be advanced in understanding the combustion process and process and propagation of flame.

• Journal of the korean Society of Automotive Engineers
• /
• v.10 no.5
• /
• pp.42-53
• /
• 1988

The effects of ignition position on combustion in a chamber with swirl flow were investigated by use of hot wire anemometer, high speed schlieren photography, and chamber pressure measurement. In experiments, the closed-constant volume combustion chamber was used, and the swirl was formed unsteadily by suction of external fluid after reducing pressure in the chamber. Results show that the effect of ignition position on combustion depends on the flow state and the flame propagation distance corresponding to each ignition position. Also, the effect of combustion promoting increases as an ignition position moves from the center of chamber to the outside, but maximum burning pressure was obtained at the position that is the shortest flame propagation distance.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.3
• /
• pp.156-167
• /
• 1996

The present work is a continuation of our previous study to investigate the effects of parameters such as equivalence ratio, hydrogen supplement rate and initial pressure on combustion characteristics in a disk-shaped constant volume combustion chamber. The main results obtained from the study can be summarized as follows. The flames in near stoichiometric mixture of methane-air are propagated with a spherical shape, but in excess rich or lean mixtures are propagated with a elliptical shape. And, they are changed to an unstable elliptical shape flame with very regular cells by increasing the hydrogen supplement rate. Also, flame is sluggishly propagated at increased initial pressure in combustion chamber. Volume fraction of burned gas and flame radius as the combustion characteristics are increased by increasing the hydrogen supplement rate, especially at the combustion middle period, but then are slowly increased by increasing the initial pressure.

• Journal of ILASS-Korea
• /
• v.17 no.3
• /
• pp.113-120
• /
• 2012

It is being more serious problems that the pollutant and the greenhouse gas emitted from the internal combustion engines due to the increasing demand of automobiles. To counteract this, as one of the ways has been studied, GDI type engine, which is directly injected into the combustion chamber and burns by a spark ignition that chose the merits of both gasoline engine and diesel engine, was appeared. The combustion phenomena in this GDI engine is known to contribute to combustion stability, fuel consumption reduction and reductions of harmful substances of exhaust gas emission, when the fuel spray of atomization being favorable and the mixture formation being promoted. Accordingly, this study analyzed the affection of ambient temperature and fuel injection pressure to the fuel by investigate the visualization of combustion, combustion pressure and the characteristic of emission, by applying GDI system on the constant combustion chamber. As a result, as the fuel injection pressure increases, the fuel distribution in the combustion chamber becomes uniform due to the increase of penetration and atomization. And when ambient temperatures in the combustion chamber become increase, the fuel evaporation rate being high but the penetration was reduced due to the reduction of volume flux, and confirmed that the optimized fuel injection strategy is highly needed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.8
• /
• pp.782-790
• /
• 2000

A numerical study has been conducted to characterize the transient pressure in a building water supply system with an air chamber by utilizing a commercial code that employs the method of characteristics. Some results produced for the purpose of verification in the study agree quite well with the previously reported. Several parameters are then varied. Among them are the valve closure time, the wave speed, the static pressure, the polytropic exponent, the air chamber volume, the inner diameter and the shape of orifice in the air chamber, etc, while the water temperature and velocity are kept constant at $20^P{circ}C $,/TEX> and 0.8 m/s, respectively, Results reported in this parametric study may be useful to understand the unsteady behavior of the system.

• Journal of the korean Society of Automotive Engineers
• /
• v.15 no.6
• /
• pp.14-22
• /
• 1993

본 글에서는 자동차엔진을 모형화한 정적연소기내의 라디칼 계측기술에 관해 언급하고자 한다. 밀폐연소기내에서 연소반응에 의해 발생된 국소 및 평균 라디칼 강도를 계측하여 순간당량비를 구할 수 있는 관계식을 유도할 수 있으며, 이것을 이용하면 기관에서 발생되는 연소과잉에 의하여 순간당량비를 구하거나, 각종 산업용 버너 등 다양한 연소기에 적용할 수 있을 것이다.