• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.55-66
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• 1993

The characteristics of the flow processes in the cylinder of the two-stroke cycle engines have become the subject of increasing and attention owing to the simplicity and the higher power per unit weight of the two-stroke cycle engine. Among the many factors which influence on the scavenging flow, the port angle is important factor. Hence, four different type models with one inlet-port and two side-ports are studied to show the effect of port angle on the laminar scavenging flow. When the inlet-port axial is relatively larger than the side-port axial angle, it is showed that the fresh charge penetrate into the burned gas and displace it first toward the cylinder head and then toward the exhaust port. When the inlet-port axial angle is much less than the side-port axial angle, the fresh charge through the inlet-port directly move toward the exhaust port. The result showed that the model A may suppress the generation of vortices in the vicinity of inlet and side prots which restrict the sufficient supply of fresh charge and obstruct the perfect displacement of all combustion products.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.36-41
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• 2005

PCV(Positive Crankcase Ventilation) valve acts as a flow control valve to get a re-combustion of blow-by gas by having it flow from a crankcase to an inlet manifold suction tube. The blow-by gas of the crankcase should be eliminated or taken properly because it cause corrosion to critical parts, and contributes to increase crankcase pressure that can cause a drop in efficiency. The excessive stress and strain on the PCV valve that remove these harmful gas would be bring the difficult on the flow rate control and failure of the valve. Those condition inevitably induce the accident. Therefore, this study purpose is FEM evaluation of the stresses and deformation in the X3 PCV model according to the change of the differential pressure between inlet and outlet. From results, the maximum equivalent stresses increased linearly according to the increase of the differential pressure at the about 50mm from the inlet position and were under the yield strength of the valve. And the deformations were relatively small regardless of the in-outlet differential pressure variation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.8-13
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• 2018

Nitrogen oxides (NOx) have recently been very influential in the generation of ultrafine dust, which is of great social interest in terms of improving the atmospheric environment. Nitrogen oxides are generated mainly by the reaction of nitrogen and oxygen in air in a combustion gas atmosphere of high temperature in a combustion apparatus such as thermal power generation. Recently, research has been conducted on the combustion that recirculates the exhaust gas to the cylindrical burner by using a piping using a Coanda nozzle. In this study, three types of burners were carried out through computational fluid analysis. Case 1 burner with the outlet of the combustion gas to the right, Case 2 burner with both sides as gas exit, Case 3 burner with left side gas exit. The pressure, flow, temperature, combustion reaction rate and distribution characteristics of nitrogen oxides were compared and analyzed. The combustion reaction occurred in Case 1 and Case 2 burner in the right direction with combustion gas recirculation inlet and Case 3 burner in the vicinity of mixed gas inlet. The temperature at the outlet was about $100^{\circ}C$ lower than that of the other burners as the Case 2 burner was exhausted to both sides. The NOx concentration of Case 1 burner at the exit was about 20 times larger than that of the other burners. From the present study, it could be seen that it is effective for the NOx reduction to exhaust the exhaust gas to both side gas exits or to exhaust the exhaust gas to the opposite direction of inlet of recirculation gas.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.413-419
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• 2013

The present study used the MILD combustor, which has coaxial cylindrical tube. The outside tube of the MILD combustor corresponds to the exhaust gas passage and the inner side tube is the furnace passage. A numerical analysis was accomplished to elucidate the characteristics of exhaust gas entrainment toward the inner furnace with the changes of venturi nozzle geometrical parameters, nozzle position, nozzle gap between high pressure air nozzle and venturi nozzle, and with the change of high pressure nozzle inlet velocity. The entrainment flow rate for the case with the high pressure air nozzle attached at the exhaust gas wall has relatively small change with the change of nozzle gap. That for the case with the high pressure air nozzle exposed to the exhaust gas has monotonically increase with the change of nozzle gap. The flow rate ratio of entrainment flow rate has considerably increase tendency with relatively lower air inlet velocity, on the other hand, that with relatively higher air inlet velocity could be seen relatively small increase.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.314-319
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• 2003

The concept of lean-premixed combustion in gas turbine combustor operation has become a standard in recent years as an effective means to meet stringent enviromental standards on NOx emissions. The combustion characteristics of 75 kW class lean premixed combustor were investigated at the conditions of high temperature and ambient pressure. The exit temperature and emissions of CO and NOx were measured at the center of exit plane. The high temperature air of $550K{\sim}650K$ was supplied through air preheater. As expected, experimental results indicate that NOx emission was increased and CO emission was decreased by increasing inlet air temperature. But CO emission measured at the center of exit plane was increased because of the non-uniform radial direction profiles. The Semi-Empirical Correlation method was applied to obtain the design point emissions of NOx and CO. Also the flame temperature, CO and NOx emissions were measured along the centerline of liner at 650K inlet air temperature to determine the position of dilution holes.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.04a
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• pp.43-50
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• 2000

The flow field of a 1 Ton/Day entrained-flow gasifier constructed in KIER was numerical simulate in this paper. The standard $k-{\varepsilon}$ turbulence model and simple procedure was used with the Primitive-Variable methods during computation. In order to find the influence factors of the flow field which may have great effects on coal gasification process inside gasifier, difference geometry parameters at various operating conditions were studied by simulation methods. The calculation results show that the basic shape of the flow field is still parabolic even the oxygen gas is injected from the off-axis position. There exist an obvious external recirculation zone with a length less than 1.0m and a small internal recirculation region nears the inlet part. The flow field inside the new gasifier is nearly similar as that of the old 0.5T/D gasifier at same position if the design of burner remains unchanged.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.105-111
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• 2003

ORVR filler neck check valve, which is one of the essential components of the vapor fuel control system, should diminish the evaporation by maintaining laminar fluid flow on refueling process. This study presents numerical. results of pressure and velocity distributions of the fluid flow in a ORVR filler neck check valve on refueling process. CFD-ACE+ has been employed for numerical analysis based on the information of experimental results of valve position as a function of inlet flow rate. No abrupt pressure change, which may causes vaporization of fuel, has been confirmed to take place on the concave surface of the valve spool. However, it is clear that some possibility exist at the mid-position of surface of valve spool and downstream according to the opening of valve.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.71-79
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• 2002

The characteristics of the catalytically supported combustion with Pd and Pd/Pt based catalyst using the bench-scaled high pressure combustor have been investigated up to 5atm. This study aimed to investigate combustion characteristics of the stable flame attached to the exit of catalyst bed and NOx emissions with respect to the position of axial and radial direction in the combustor. NOx emissions were increased along the axial distance after the catalyst bed exit and radially decreased from the center to the wall of the combustor. At the higher pressure, the NOx emission decreased slightly due to the lower flame temperature in the combustor at the high pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.103-109
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• 2013

In this study, we performed a numerical study of hydrogen/air combustion in the combustion chamber of an ultra micro gas turbine. The supply flow rate and equivalence ratio are used as variables, and the commercial computational fluid dynamic program (STAR-CCM) is used for the numerical study of the combustion. The flow rate significantly affects the flame position, flame temperature, and pressure ratio between the inlet and the outlet. The flame position is close to the outlet in the combustion chamber, and the flame temperature and pressure ratio monotonously increases with the supply flow rate. The change in the equivalence ratio does not affect the flame position. The maximum flame temperature occurs under stoichiometric conditions.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.64-69
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• 2015

Marine diesel engines with high thermal efficiency and fuel diversity used for propulsive power have been taking charge of important position on marine transport. However, marine environment has recently focused on emissions such as nitrogen oxide and sulfur oxide which is generated from combustion of low grade fuels. EGR(Exhaust gas recirculation) system is one of effective methods to reduce the nitrogen oxide emission from marine diesel engines. In general, it is considered that recirculating gas influences fuel combustion and emissions in diesel engines. However, along with positive effects of EGR, the EGR system using fuels of including high sulfur concentration should be considered about re-combustion and activation of sulfur dioxide in recirculating gas. Therefore, in experimental study, an author investigates effects of sulfur dioxide mixture concentration in intake air on combustion and exhaust emission characteristics in a direct injection diesel engine. In results, change of sulfur dioxide concentrations in intake air had negligible impact on combustion chamber pressure, rate of heat release and emissions compared with effects of oxygen decreasing and carbon dioxide increasing of EGR.