• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.153-159
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• 2004

We have investigated the feasibility of using differential pressure(pressure drop) of gas turbine meter to diagnose turbine performance degradation caused by mechanical wearing damage and/or dirt buildup or erosion. If the differential pressure between the upstream piping and the throat of a turine meter can be correlated to meter flow rate over the operating range of the meter, then a relatively simple differential pressure measurement in the filed might be used to detect meter performance changes. To test this method, we have conducted two experimental simulation on Straightener Integrated Type(SIT) turbine meter. One is fur dirt buildup on turbine blade, the other is for eccentricity of the blade. Results show that this method provide a reliable measure of performance degradation and is useful maintenance indicator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.723-729
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• 2019

Turbochargers are an effective device to reduce the fuel consumption. In this study, the mass flow rate of pulsating flow in the twin-scroll turbocharger for the gasoline engine of passenger vehicles was measured. Pulsating flow was achieved using a pulse generator and the mass flow rate of the unsteady pulsating flow was analyzed by comparing it with those of the steady flow. The pulse generator consisted of a rotating upper plate and a fixed lower plate. To measure the mass flow rate of unsteady flow, the orifice flow meter equipped with the difference pressure transducer was used. To analyze the low speed performance of the turbocharger, the measurement was carried out in the speed of turbocharger from 60,000rpm to 100,000rpm. The mass flow parameters of the unsteady pulsating flow showed a large difference compared to those of the steady flow. Those of the unsteady flow showed the hysteresis loop surrounding the mass flow parameters of the steady flow and the maximum variation of the mass flow parameters were 5.0 times those of the steady flow. This phenomenon is the result of the filling and emptying the turbine volute space due to pulsating flow.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2152-2154
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• 2003

전력계통 및 발전기의 안정 운용을 위해 발전기 제어계의 정밀 제어와 정확한 계통 해석을 위한 발전기 관련 정밀 파라미터 취득 및 관리가 요구되는 상황에서 발전기 현장시험과 발전기 관련 안정도 해석용 데이터 취득이 필요한 실정임. 현장 시험(발전기 제어계 특성시험)을 통해서 취득한 데이터를 가지고 모델링 및 제어정수를 조정하여 전력계통 안정도 해석용 데이터 베이스를 구축하게 되는데, 여자기 형식에 따라서 계단 입력 신호가 주어졌을 때 시간응답 특성이 약간씩 차이가 나게 됨. 그리고 발전기 제어계 특성시험은 발전기 직접 관련 데이터 및 원동기(터빈) 입력신호(주증기 유량신호, 주증기 제어밸브 개도 등)까지 측정하게 되는데, 본 논문에서는 발전기 여자제어에 관련된 부분만을 살펴 보았음.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.265-271
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• 2000

Orifice meters and turbine meters are frequently used for measuring gas flow in gas industry. However, to insure the accuracy of the measurement, a certain length of the meter run at the upstream of the flow meter is required. The objective of this study is to analyze flow measurement errors of the orifice meter quantitatively for shorter lengths of the meter runs than those suggested in the standard manuals with variation of diameter ratio( $\beta$ ratio) and flow rate and also to analyze flow measurement errors of the turbine meter with and without straightener. The test results showed that the flow measurement errors of the orifice meter were inversely proportional to the diameter ratio. In other words, when the diameter ratio is 0.3 and 0.7, the measurement error is $-7.3\%$ and $-3.5\%$, respectively. the main reason of the measurement error is due to the swirl effect from the configuration of the meter run at the upstream of the flow meter. In case the length of the meter run is shorter than that suggested In the standard, the swirl effect is not removed completely and it affects the flow meter's performance. As mentioned above, the less the pipe diameter ratio, the mon the flow measurement error. It means that the swirl effect on the orifice meter increases as the $\beta$ ratio decreases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.699-707
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• 2017

This study presents a comparative thermodynamic analysis of subcritical and transcritical organic Rankine cycles for the recovery of low-temperature heat sources considering nine substances as the working fluids. The effects of the turbine inlet pressure, source temperature, and working fluid on system performance were all investigated with respect to metrics such as the temperature distribution of the fluids and pinch point in the heat exchanger, mass flow rate, and net power production, as well as the thermal efficiency. Results show that as the turbine inlet pressure increases from the subcritical to the supercritical range, the mismatch between hot and cold streams in the heat exchanger decreases, and the net power production and thermal efficiency increase; however, the turbine size per unit power production decreases.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.36-41
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• 2010

Design, manufacture and calibration procedures of a venturi pipe flowmeter for airflow measurement in altitude engine test were discussed. Altitude engine test using venturi pipe was given as an example. The venturi was designed per the ISO standard of ISO5167, and was intented to include the entire airflow range in the test envelope of the gas turbine engine. Measurement uncertainty analysis was performed in the design procedure to investigate the effect of venturi geometry and sensor specification upon the measurement uncertainty. Manufacturing process was designed to minimize the deviation from the geometry of design. Calibration was performed to get the relationship between the discharge coefficient and the pipe Reynolds number. Then the uncertainty was assessed again using real data acquired during engine test. Through these procedures, it was possible to maintain the uncertainty of airflow measurement under 1 % for most of the operating envelope of the gas turbine engine. The discharge coefficient of the venturi pipe showed agreement with the value suggested in the ISO standard ISO5167-4 within 0.6 %.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.93-97
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• 2010

The energy balance program which can balance the relations among energy, mass flow, pressure in the staged-combustion cycle of the liquid rocket engine has been developed. The modular approach has been chosen for the analysis; the engine cycle consists of the elements from the predefined component analysis program. The engine with the staged-combustion cycle has been decomposed into several principal component modules, such as a thruster chamber, turbopumps, turbines, supply system components and a pre-burner. The program has been verified with comparison of the results to the selected data of the space shuttle main engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.293-301
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• 2017

A Sub-kWe small-scale experimental test loop was manufactured to investigate characteristics of the supercritical carbon dioxide power cycle. A high-speed turbo-generator was also designed and manufactured. The designed rotational speed of this turbo-generator was 200,000 rpm. Because of the low expansion ratio through the turbine and low mass flowrate, the rotational speed of the turbo-generator was high. Therefore, it was difficult to select the rotating parts and design the turbine wheel, axial force balance and rotor dynamics in the lab-scale experimental test loop. Using only one channel of the nozzle, the partial admission method was adapted to reduce the rotational speed of the rotor. This was the world's first approach to the supercritical carbon dioxide turbo-generator. A cold-run test using nitrogen gas under an atmospheric condition was conducted to observe the effect of the partial admission nozzle on the rotor dynamics. The vibration level of the rotor was obtained using a gap sensor, and the results showed that the effect of the partial admission nozzle on the rotor dynamics was allowable.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.54-60
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• 2017

In order to identify the characteristics of the flame transfer function gain, cold-flow transfer function was introduced, which is the part of the combustion instability research. Nitrogen and carbon dioxide was used to obtain the cold-flow transfer function and input/output variables was measured by hot wire anemometry. Density and fluid flow rate affect the cold-flow transfer function gain and peak frequency. In addition, acoustic resonance frequency affects the peak frequency of gain in the fuel feeding line.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.107-114
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• 2017

A turbocharger is an engine supercharger that is driven by exhaust gas. It improves the output and fuel efficiency by increasing the charging efficiency of the mixture gas, which is achieved by changing the rotatory power of the turbine connected to the exhaust passage. It is important to control the supercharging for this purpose. A nozzle slide joint is one of the core parts. Austenitic stainless steel is currently used as the material for this part, and its excellent mechanical properties include high heat resistance and corrosion resistance. However, because of its poor machinability, there are many difficulties in producing products with complicated shapes. Machining is used in the production of nozzle slide joints for high dimensional accuracy after metal powder injection molding. As design variables in this study, we investigated the sintering temperature, product stress, deformation rate, radius of curvature of the punch, and angle of the chamfer punch, which are related to the strain and shapes. The goal is to suggest a forming process using Nitronic 60 that does not require machining to manufacture a nozzle slide joint for a turbocharger. Accordingly, we determined the best process environment using finite-element analysis, the signal-noise ratio, and the Taguchi method for experiment design. The relative density and hydrostatic pressure of the final product were in accordance with the results of the finite element analysis. Therefore, we conclude that the Taguchi method can be applied to the design process of metal powder injection molding.