• 한국산학기술학회논문지
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• 제18권3호
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• pp.711-717
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• 2017

본 논문은 엔진 다운사이징의 관점에서 널리 사용되는 터보과급기 로터의 관성모멘트 측정에 관한 연구이다. Trifilar 방법을 이용하여 관성모멘트를 측정하기 위한 장치를 설계 제작한 후, 장치를 검증하기 위하여 교정로터의 관성모멘트를 측정하였다. 측정의 변동계수는 0.43%, CAD 도면의 관성모멘트와 비교하여 0.75% 오차를 보여 개발된 측정장치가 로터의 관성모멘트 측정에 적합함을 확인하였다. 소형 터보과급기의 터빈 로터와 압축기 휠 각 2개에 대한 관성모멘트 측정을 수행하여 1.0% 미만의 변동계수를 보여 정밀한 측정이 가능함을 보였다. 그러나 CAD 도면의 관성모멘트와 비교한 오차는 터빈 로터는 2.76%와 1.30%로 양호하였으나, 압축기 휠의 경우 27.6%와 24.4%로 상당히 크게 나타났다. 연구에 사용된 압축기 휠은 질량이 소형으로 상대적으로 공기저항이 크고 정확한 주기 측정의 어려움으로 큰 오차를 보였다. 따라서 터빈 로터와 압축기 휠을 결합한 상태에서 측정한 값에서 터빈 로터의 관성모멘트를 빼는 간접 방법으로 측정을 수행하였다. 이때 압축기 휠의 관성모멘트 측정에서 1.2% 미만의 변동계수를 보이고 오차는 5.68%, 7.88%의 값을 보였다.

• 한국자동차공학회논문집
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• 제24권1호
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• pp.33-38
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• 2016

The turbocharger is an essential component to realize the engine down-sizing. The moment of inertia of turbocharger rotor is an important parameter with respect to acceleration performance of the vehicle. It can be calculated from the CAD software based the geometry data and the material properties. But the accurate value of the inertia of turbocharger rotor must be measured through the experimental method. In this study, the measurement of moment of inertia of turbocharger rotor for 2.0 L spark-ignition engine was carried out. First, an experimental equipment using a trifilar method was designed and fabricated. Some optical devices, that is, photo sensor, counter, convex lens, etc, were used to increase the accuracy of the measurement. Second, error sensitivity for the equipment was analyzed. The error of period time and the radius can give big affects to the accuracy of the moment of inertia. When the amount of error of these two were each 1.0 %, maximum error of the moment of inertia was under 3.0 %. Third, the calibration for the equipment was performed using a calibration rotor which has similar shape to turbine rotor but simple. Calculated value from CAD software and measured one for the calibration rotor were compared. The total error of the equipment and the measurement is about 1.3 %. This result shows that the equipment can give the good result with resonable accuracy. Finally the moment of inertia of the turbine rotor and compressor wheel were measured. The coefficient of variations, the ratio of standard deviation to mean value, were reasonably small at 0.57 % and 0.73 % respectively. Therefore this equipment is suitable for the measurement of the moment of inertia of the turbine rotor and compressor wheel.

• 한국유체기계학회 논문집
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• 제13권5호
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• pp.35-42
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• 2010

This paper deals with the development of analytical model of a turbocharger and its detail rotordynamic analysis. Two analytical models, which are verified by experimental modal testing, are proposed and the analytical model including rotor shaft extended to compressor and turbine wheel end side is chosen. A rotordynamic analysis includes the critical map, Campbell diagram, stability, and unbalance response, especially nonlinear transient response considering nonlinear fluid film force at bearings. Although the linearized analysis accurately predicts the critical speeds, stability limit, and stability threshold speed, the predicted vibration results are not valid for speeds above the stability threshold speed since the rotor vibrates with a subsynchronous component much larger than the one synchronous with rotor speed. Hence, for operating speed above the stability threshold, a nonlinear transient analysis considering nonlinear fluid film force must be performed in order to accurately predict vibration responses of rotor and guarantee results of analysis.