• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.4
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• pp.69-74
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• 2014

A waste gate valve (WGV) assembly for a gasoline turbocharger is typically manufactured by means of precision casting. In this study, however, it was newly manufactured in a more innovative way, metal injection molding (MIM) using Inconel 713C alloy, and its performance was tested in a 1.6L direct injection gasoline engine by a thermal shock durability test that lasted 300 hours, after which the results were compared to those of a precision-cast WGV assembly with regard to the engine intake boost pressure, turbine wheel speed, and transient intake pressure. It was found that the two WGV assemblies showed similar performance levels throughout the durability test.

• The KSFM Journal of Fluid Machinery
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• v.7 no.5 s.26
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• pp.20-28
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• 2004

Static and dynamic structural analyses of a turbine bladed-disk for a liquid rocket turbopump are performed to investigate the safety level of strength and vibration at design point. During operation, turbopump is exposed to various external loads. Therefore, the effects of them should be carefully considered and properly modeled. First, due to the high rotational speed of the turbopump, effects of centrifugal forces are considered in the structural analysis. Thermal load caused by severe temperature differences is also considered. A three dimensional finite element method (FEM) is used for linear and nonlinear structural analyses with modified Newton-Raphson iteration method. After the nonlinear solution is obtained from the structural analysis, dynamic characteristics are obtained as a function of rotational speed from the linearized eigenvalue analysis at an equilibrium position. From the analysis results, characteristics of stress distribution and vibration were thoroughly examined and investigated.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.333-339
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• 2003

Steady and unsteady cavitation characteristics of turbopump inducer were investigated in this paper. To see the effect of blade angle on the inducer performance, three inducers with inlet tip blade angle of $7.8^{\circ},\;7.0^{\circ},\;6.1^{\circ}$, respectively, were tested. For $7.8^{\circ},\;7.0^{\circ}$ inducers in the non-cavitating condition, head decreased linearly with flow rate, but head-flow rate curve had a dip at the flow coefficient ${\Phi}=0.065\;for\;6.1^{\circ}$ inducer. Rotating cavitation and cavitation surge were found in the $7.8^{\circ},\;7.0^{\circ}$ inducers in the cavitation tests. During the rotating cavitation one cell rotated at the same rotational speed as that of the inducer. The cavitation surge did not rotate and the oscillating frequency was $7{\sim}20\;Hz$. From the curve of the critical cavitation number versus flow rate, it was found that the steady cavitation performance of $6.1^{\circ}$ inducer was much lower than that of $7.8^{\circ},\;7.0^{\circ}$ inducers.

• Journal of Hydrogen and New Energy
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• v.33 no.4
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• pp.437-445
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• 2022

This paper presents an experimental study on the main management factors of the condenser contamination such as fouling and corrosion for the R-134a turbo-chiller to save energy, reduce corrosion rates, and reduce maintenance costs through the application of condenser non-cleaning water treatment chemical. The series of experiment is conducted using combining oxidative microbial sterilizers, non-oxidizing microbial sterilizers, and anti-corrosion agents. The leaving temperature difference and corrosion rates for three different combination of chemicals are collected and analyzed. The experimental results show that the cost reduction (4,066,000 Won/year) of the disinfectant (FT-830) can be achieved by adding the oxidative disinfectant (NaOCl) and the non-oxidizing disinfectant (NX-1116). The LTD value is maintained at 1.9℃, and the corrosion rates of copper and carbon steel specimens are 0.07 mpy and 1.61 mpy, respectively.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.75-80
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• 2007

It is necessary to analyze the contact phenomena in order to effectively design the machine components with contact surfaces. In general, the contact action is highly nonlinear and irreversible because we cannot predict the contact regions and conditions. Recently, the finite element method is used to analyze the contact problem. In this paper, the contact element method is applied to avoid the mesh refinement and iterative calculation of general contact algorithms. By use of it, the deformation and stress concentration of turbo compressor rotor are computed. It shown that the contact element is convenient analysis and the results are relatively accurate.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.41-45
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• 2009

The new cooling fan for various parts & equipments of KTX is developed and evaluated to improve fan performance and durability. The characteristic curve of the developed fan is obtained according to KSB 6311 of performance test regulation. 70 degree of the installation angle of blade makes the fan to produce a maximum flow rate. This angle is found out through trial-error and is confirmed through the verification test. In order to improve the blade strength, the blade is produced by a draw forming. The adoption of AL50 reduces a fan weight by 6 kg. The new blade makes a static pressure 170 (mmAq), a discharge rate $140(m^3/min)$, a rotational speed 2886 (rpm) at the power 10 kw. which results 54% of the static pressure improvement relative to the original blade.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.298-303
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• 2004

The active magnetic bearing system for a TMP consists of four couples of magnets, five gap sensors with its amplifiers and a digital PID controller. For stabilizing and providing damping, digital PID controller is applied for each control axes and the inter-axis cross feedback controller is also applied to suppress low frequency vibration caused by gyroscopic moment of the rotor. Therefore in this paper, a digital controller of magnetic bearing for a TMP is design and examined.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.81-87
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• 2004

A 3-D FEM (Finite Element Method) analysis of the turbo-blower shaft attached to a fuel cell was performed using Lanczos algorithm. The modal analysis was analyzed in order to investigate natural frequency and maximum displacement for 10 times. It was found that the first mode of natural frequency is 109.1Hz with the maximum displacement of 0.16mm while the tenth mode of natural frequency is 2464Hz with the maximum displacement of 0.25mm. Consequently, the results of modal analysis of the turbo-blower for a fuel cell system show good dynamic responses.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.2
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• pp.11-22
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• 1993

오늘날 자동차용 엔진에 대한 사용자의 요구는 여러가지가 있지만 그 중에서도 손쉬운 운전, 고 출력화, 응답(response)의 향상 등의 요구는 지금 이후로도 계속되리라 생각된다. 슈퍼차저도 이러한 요구에 의하여 사용되고 있으며 이제는 엔진의 보조적 향상책으로 뿐만 아니라 엔진에 있어서 필요 불가결한 것으로써 확실히 정착되리라 생각된다. 본 고에서 살펴본 바에 의하면 스크류식 슈퍼차저가 테스트된 4종류의 슈퍼차저중에서 가장 나은 성능, 과급압, 토르크를 주고 있으며, 또한 가장 소형이며 경량이다. 또한 스크류로타는 팽창기로써 효율 높게 작용할 수 있어, 이의 채용으로 기존의 터보콤파운드시스템 보다 8-10% 에너지 효율이 높게됨이 알려지고 있다. 그러므로 스크류로타를 이용한 터보콤파운드시스템은 기존의 어떤 시스템보다도 효율이 높은 시스템으로 발전할 수 있는 가능성이 높아 이의 연구가 적극 추진되어야 하겠다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.97-102
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• 2016

Since vibrations in rotating machinery is a direct cause of performance degradation and failures, it is very important to predict the level of vibrations as well as have a method to lower the vibrations to an acceptable level. However, the changes in balancing during installation and the vibrational modes of the support structure are difficult to predict. This paper presents a method for predicting the unbalanced response of a turbo-compressor supported by active magnetic bearings (AMBs). Transfer functions of the rotor are obtained through system identification using AMBs. These transfer functions contain not only the dynamics of the rotor but also the vibrational modes of the support structure. Using these transfer functions, the unbalanced response is calculated and compared with the run-up data obtained from a compressor prototype. The predictions revealed the effects of the support structure, validating the efficacy of the method.