• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.775-780
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• 2003

In this study, a computer analysis has been developed for predicting the pipe pressure of the intake and exhaust manifold in a single cylinder engine. To get the boundary conditions for a numerical analysis, one dimensional and unsteady gas dynamic calculation is performed by using the MOC(Method Of Characteristic). The main numerical parameters are the variation of the exhaust pipe diameters to calculate the pulsating flow when the intake and exhaust valves are working. As the results of numerical analysis, the shapes and distributions of the exhaust pipe pressures were influenced strongly on the cylinder pressure. As the exhaust pipe diameter is decreased, the amplitude of exhaust pressure is large and the cylinder pressure was showed low in the region of intake valve opening time.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.130-135
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• 1995

In this paper, the numerical simulation of the method of characteristics for a two-stroke SI engine was carried out, and the scavenging efficiency and the performance of single engine with two types of exhaust system, that is, a pipe exhaust system and a tuned exhaust system, were predicted and compared. The conculusions are obtained as follows. (1) The method of characteristics of hometropic flow considering the friction and the variation of area is useful to predict the scavenging efficiency and the performance of the two-stroke engine. (2) The shape of exhaust system effects directly on the scavenging and the trapping efficiency. (3) A tuned exhaust system consisted of the diffuser and the convergent nozzle makes the plugging pulse and therefore enhances the scavenging and the trapping efficiency. (4) It may be possible to design the optimum exhaust system by using the plugging pulse.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.76-83
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• 2001

An experimental investigation has been performed on the steady flow in exhaust system. When individual flow coming from exhaust manifold entered UCC, the inlet conditions at entry to the diffuser in UCC were affected by the upstream pipe and manifold works. But those effects of the inlet condition on flow through monolith are negligible because the flows are concentrated on the center of monolith regardless of inlet flow distribution. To improve the flow distribution, we installed the cone type circular ring in diffuser of UCC. This led to increasement of flow uniformity, but there was minor increment of pressure drop.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2642-2647
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• 2007

This study represents numerical study on the thermal and fluid flow characteristics of exhaust gas in a motorcycle muffler. The reference engine was used 124.cc small displacement. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the exhaust gas that flow into a motorcycle muffler. The STAR-CD S/W used to three dimensional steady state CFD analysis in a muffler. And than We got the information of static pressure it is used to structural analysis ant the first baffle plate using the commercial CAE code ANSYS workbench. Exhaust gas flow third chamber from frist chamber and running second chamber. A simulation result shows that each chamber of muffler temperature is about 460 K, 445 and 463K and pressure is about 22,000 Pa, 16,000 Pa and 10,000 Pa.

• 한국생산제조학회지
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• 제21권2호
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• pp.196-201
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• 2012

This study represents numerical study on the thermal and fluid flow characteristics of exhaust gas in a motorcycle muffler. The engine generates 125cc of displacement. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the exhaust gas that flow into a motorcycle muffler. The STAR-CD S/W used to analyze three dimensional steady state and transient in a muffler. The Navier-Stokes Equation is solved with SAMPLE and PISO method in cartesian coordinates system. As the numerical result, it could be confirmed pulsating pressure generated from inlet of muffler become closer to the atmospheric pressure through baffle. Also the numerical result was almost identical to experimental result and, through the comparison, the reliability of numerical result was confirmed.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.127-133
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• 2008

Since the 1960's, exhaust gas recirculation(EGR) has been used effectively in spark ignition(SI) engines to control the exhaust emissions of the oxides of nitrogen(NOx). The most important requirements for the application of EGR systems to conventional SI engines are controllable flow rate and good dynamic response. In order to evaluate the characteristics of the electronic EGR valve, a test bench which is consisted of blower, heater, air flow meter and driving unit for electronic EGR valve was set up to simulate engine operating conditions. During the tests, the valve actuation parameters were controlled and the valve lifts and flow rates were measured to infer the characteristics of EGR valve. The results confirmed the capabilities of mathematical analysis and it seems that the correction for the valve lift and potentiometer output is necessary to achieve precise control of EGR rates.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.77-82
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• 2003

A parametric study was conducted on pressure drop in a catalytic converter for automobile. In this work, we proposed a new pressure drop relation which contains the various parameters needed to calculate and got a few results. In a monolith of catalyst, the flow originally turbulent flow changes to laminar flow and thus the pressure drop through the monolith is linearly proportional to the velocity. The exhaust pressure is doubly affected by the increase of mean velocity and length when we decrease the diameter of monolith while the volume keeps constant. Theoretical parameters such as $\alpha$ and $\beta$ are suggested to use as a reference value when there is no a experimental data. Especially in the part load test, these values should be modified to consider the property change of exhaust gas.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2002년도 제19회 학술발표대회 논문초록집
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• pp.37-40
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• 2002

The engine performance test was carried out to investigate the effects of breath and exhaust on the performance of a reciprocating engine for small aircraft. In this test, three valves to control flow areas of a inlet and two outlets were used, the engine manifold pressure and the static thrust of propeller were measured in nine breath/exhaust conditions. Generally, small variations on the performance were showed as the test conditions were changed. The manifold pressure was increased as flow area of the inlet or the outlet was decreased in normal condition, however it was decreased as both flow areas were decreased. The static thrust of propeller was showed similar as the manifold pressure.

• 대한기계학회논문집
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• 제19권3호
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• pp.796-805
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• 1995

For the purpose of improving performances of a turbocharged diesel engine at low speed, this study investigates the effects of the injected air for the performances and flow characteristics in the intake and exhaust pipes by using the computer simulation with test bed. In the theoretical analysis, the whole flow system, including engine cylinders and intake and exhaust pipes, is calculated numerically by the method of filling and emptying. From the results of this study, the following conclusions may be summarized. Increasing injected air pressure into the pipe of compressor exit brings about the improvement in a performance and flow characteristics of intake and exhaust pipes under full load operating conditions at 1000 rpm of the engine speed, but shows trends of the inferior performances under no load operating conditions at 2000 rpm of the engine speed.

• 한국분무공학회지
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• 제20권2호
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• pp.76-81
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• 2015

Swirl flow has an impact on the stabilization of the flame by the recirculation flow, improvement of the combustion efficiency. The swirl flow in the gun type burner is created by the spinner which is inside the airtube that guide the combustion air. Burner has generally the combustion device composed electronic spark plug, injection nozzle, combustion device adaptor, and spinner. These inner components change the air flow behavior passing through airtube. So, this study analyzed exhaust flow characteristics of the gun type burner according to the ratio of airtube diameter. Turbulence characteristics by the spinner was mean velocity, turbulence intensity, kinetic energy, shear stress and flattness factor of the air flow of axial direction and tangential direction from the exit of the airtube.