• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.400.2-400
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• 2002

Recently rotating machines have became high speed and high Power and light weight. Bearings are one of the main components which influence power loss and stability of rotating machines. Appropriate bearing should be selected with considering characteristics of rotating machine. Floating ring journal bearing(FIB) consists of an inner film and outer film, and possess high damping and stability. FJB has been for adopted into turbocharger for the high stability at high operating speed. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.913-917
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• 2007

The turbocharger for a vehicle is consisting of a centrifugal compressor and turbine. These compressor and turbine are vibrating and emitting noises through the T/C body, exhaust system (Catalyst, Bellows, Pipe, etc) and Intake system (Hoses, Intercooler pipes, Intercooler) as rotating. A turbocharger cold test bench is constructed to reduce these noises, especially for the purpose of realizing transient operating environment and oil temperature control to simulate the vehicle operating characteristics with intake system and exhaust system. This research laid the groundwork to develop a lower noise level T/C through understanding the mechanism of the noise source of T/C.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.667-669
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• 2014

Development of 3 cylinder turbo charger engine is increasing due to engine down-sizing, cost reduction and emission regulations. However, 3 cylinder engine makes higher Exhaust manifold gas pressure(P3) pulsation than 4 cylinder engine and it generate boosting air with high pulsation. The mechanical waste-gate turbocharger just controlled by the boosting air has higher movement because of this high pulsation boosting air. This causes high vibrations to wasted gate and accelerate wear of the linkage system. So we need to understand out of the exhaust gas pressure pulsation changed by turbocharger compressor pressure(P2) Pulsation. In this study, we discuss how to prevent to abnormal movement of the turbo actuator by stabilized P2 Pulsation.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.129-134
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• 2010

A diesel engine is equipped with a turbocharger for providing more power at a low engine speed region by supplying charge air to combustion chambers. The turbocharger makes it possible to satisfy stringent emission regulations and customers' demand of enjoying the fun to drive by increasing engine performance. However, the turbocharger has the disadvantage of making BPF(Blade Passing Frequency), hissing, surge, whistle, and blow noises. Among them, reducing the blow noise, a narrow-band noise(a general range : 1800~2000Hz), is possible by using a resonator that controls the narrow frequency band governing the resonance in the intake system. In this study, the optimum location of the resonator is found by employing Boost as a CAE(Computer Aided Engineering) tool and is confirmed by experiments of an engine dynamo test and a real vehicle test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.79-84
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• 2009

Turbocharger has been widely used in many passenger cars in application with diesel engines because of high power and fuel efficiency. However, flow-induced noise (whoosh or hissing noise) which is generated within a compressor during its operation at marginal surge line can deteriorate noise characteristics. Hissing noise excitation is associated with the generation of turbulence within the turbocharger compressor and radiated through the transmission path in a turbocharger system. In this study, a expansion muffler with lids is devised and installed in the transmission path to reduce the hissing noise. Acoustic and fluid dynamic characteristics for the muffler are investigated which are related to the unsteadiness of turbulence and pressure in the turbocharger system. A transfer matrix method is used to analyze the transmission loss of the muffler. A simple expansion muffler with lids is proposed for the reduction of high frequency component noise. Turbulence simulation is carried out by a standard k - ${\varepsilon}$ model. An optimal design condition of the muffler is obtained by extensive acoustic and fluid dynamic analysis on the engine dynamometer with anechoic chamber. A significant reduction of the hissing noise is achieved at the optimal design of the muffler as compared with the conventional muffler.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1038-1043
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• 2002

The floating ring journal bearing is attraction for high-speed turbo machinery applications, including turbochargers and aircraft accessory equipment, because it is not only simple and easy to make and to replace in the field but also it seems to have adequate high speed stability characteristics. Therefore, an analysis method of dynamic properties of floating ring journal bearing is presented. The static equilibrium locus of inner film and outer film are calculated by using the impedance description. The equivalent stiffness and damping coefficients of floating ring journal bearing are composed by using the equilibrium of torque between inner film and outer film. Then, a stability analysis of turbocharger shaft system supported with floating ring journal bearing has been performed.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_1
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• pp.977-983
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• 2023

The tank uses a twin turbo diesel engine equipped with two turbocharger systems for high output. The main component of the turbocharger system is the turbine housing through which the exhaust flows. Turbine housing is manufactured through a sand casting process, taking into account the shape and material characteristics according to the environmental conditions in which it is used. Currently, turbine housing is imported, and local production is necessary. In this study, basic research was conducted to localize the turbine housing of a tank diesel turbo engine. Reverse engineering and finite element analysis of the imported turbine housing were performed. The prototype of the turbine housing was printed using FDM and PBF 3D printers. The prototype of the turbine housing printed with an FDM 3D printer has an overall appearance similar to 3D modeling, but the printed surface of the whorl part is rough. The prototype printed with the PBF 3D printer is completely identical to the 3D modeling, including the whorl part.

• The KSFM Journal of Fluid Machinery
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• v.19 no.6
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• pp.43-49
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• 2016

A performance analysis of a gasoline engine with a 2-stage turbocharger system for unmanned aerial vehicle(UAV) was conducted. One dimensional system analysis was conducted for the requirements of turbochargers and adequate turbochargers were selected from commercially available models for automobiles. Modeling and simulation were performed by Ricardo WAVE. Gasoline engine modeling was based on a 2.4 L 4-cylinder engine specification. The selected turbochargers and intercoolers were added to the engine model and simulated at 40,000 ft altitude condition. The results of the engine model and 2-stage turbocharger system model simulation showed break power 93 kW which is appropriate power required for the engine operation at the ambient conditions of 40,000 ft altitude.

• Tribology and Lubricants
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• v.31 no.6
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• pp.302-307
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• 2015

The use of turbocharger in internal combustion engines has increased as it is a key components for improving system efficiency without increasing engine size. Because of increasing demand, many studies have evaluated rotordynamic performance so as to increase rotation speed. This paper presents a linear and nonlinear analysis model for a turbocharger rotor supported by a floating ring bearing. We constructed rotor model by using the finite element method and approximated bearings as being infinitely short. In the linear model, we considered fluid film force as stiffness and damping element. In nonlinear analysis, calculation of the fluid film force involved solving the time dependent Reynolds equation. We verified the developed model by comparing the results to those of previous research. The analysis results show that there are four unstable modes, which are rigid body modes combining ring and rotor motion. As the rotating speed increases, the logarithmic decrement shows that certain unstable modes goes into the stable area or the stable mode goes into the unstable area. These unstable modes appear as sub-synchronous vibrations in nonlinear analysis. In nonlinear analysis frequency jump phenomenon demonstrated in several experimental studies appears. The analysis results also showed that frequency jump phenomenon occurs when the vibration mode changes and the sequence of unstable mode matches the linear analysis result. However, the natural frequency predicted using linear analysis differs from those obtained using nonlinear analysis.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.86-87
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• 2005

The combustion characteristics of the D.I. diesel engine are largely dependent on the air-fuel ratio and the gas exchange process. The main factors are the shape of combustion chamber, fuel injection system, air flow inside the cylinder, intake air mass flow rate and so forth. Because these factors affect the combustion in a mutual and combined manner, it is very important to clearly understand the correlation of these factors in order to provide the combustion improvement plans. In this paper, we studied the performance and the gas exchange process of marine four-stroke engine using the engine cycle simulation. Also, we predicted briefly turbocharger engine matching.