• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.82-88
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• 2006

In order to effectively reduce thermal loads on regenerative cooled walls, fuel cooling injectors and film cooling devices have often been employed. The present study has established a numerical methodology for prediction of performance and near-wall temperature distribution taking into account the nonuniform mixing due to these additional cooling devices. A correction procedure for main propulsive parameters has also been proposed based on comparison between prediction and experimental data. Under the computational framework of this study, the predicted results were in good agreement with hot-firing test data for a 30 tonf-class full-scale combustor at the design and off-design conditions. As a consequence, the present numerical method is expected to be useful for design and evaluation of regenerative cooled liquid rocket thrust chambers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.201-204
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• 2004

In this study, the GSP and in-house numerical codes have been used for analyses of the on-design, static off-design and dynamic off-design performances. Through the various missions including altitude, velocity, and power variations static engine performance have been investigated. The dynamic engine performances based on these complicated variations have been also analysed. Especially, the power, engine rpm and heat overload characteristics of a turbine have been estimated with the response time through the control of a throttle setting rather than a power setting. It could be applied to the FADEC system as an engine control device.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2171-2180
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• 1991

An analysis model for off-design performance of radial inflow turbines with or without variable area guide vane is developed, where two important factors in loss models, total pressure ratio between variable area guide vane exit and scroll casing inlet and rotor loss coefficient are determined without experimental data. The analysis results show that the predicted trends with or without variable area guide vane are consistent with the experimental observations. The comparison of present method with the well-known NASA off-design performance analysis program shows that the mass flow rate and static efficiency by present analysis are in good agreement with those by the NASA program. Therefore, this method can be used to predict off-design performance of radial inflow turbines with validity of the loss models used by present analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1077-1084
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• 2000

In this work, a modified stage-stacking method for the performance prediction of multi-stage axial flow compressors is proposed. The method is based on a simultaneous calculation of all interstage variables (temperature, pressure, flow velocity) instead of the conventional sequential stage-by-stage scheme. The method is also very useful in simulating the effect of changing angles of the inlet guide vane and stator vanes on the compressor operating characteristics. Generalized stage performance curves are used in presenting the performance characteristics of each stage. General assumptions enable determination of flow path data and stage design performance. Performance of various real compressors is predicted and comparison between prediction and field data validates the usefulness of the present method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3357-3368
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• 1994

Total pressure losses required to calculate the total-to-total efficiency are estimated by integrating empirical loss coefficients of four loss mechanisms along the mean-line of blades as follows; blade profile loss, secondary flow loss, end wall loss and tip clearance loss. The off-design points are obtained on the basis of Howell's off-design performance of a compressor cascade. Also, inlet-outlet air angles and camber angle are obtained from semi-empirical relations of transonic airfoils' minimum loss incidence and deviation angles. And nominal point is replaced by the design point. It is concluded that relatively simple loss models and Howell's off-design data permit us to calculate the off-design performance with satisfactory accuracy. And this method can be easily extended for off-design performance prediction of multi-stage compressors.

• Journal of Energy Engineering
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• v.9 no.4
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• pp.295-302
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• 2000

증발열량 석탄가스 연료를 사용하는 석탄가스와 복합 발전 플랜트의 성능 및 NOx 배출량을 동시에 예측하기 위한 모사 방법을 제시하였다. 본 방법은 복합 사이클의 열역학적 해석 기법을 토대로, 석탄가스화 복합발전 플랜트의 시스템 연계 및 석탄가스 연소에 의한 탈설계점 효과를 예측하는 모델들을 포함하고 있다. 본 방법에 의한 전산 모사 결과와 천연가스를 사용하는 복합발전소의 실제 시험 결과를 비교함으로써, 본 방법의 예측정확도를 검증하였다. 본 모사 방법을 이용하여, 서로 다른 4가지 석탄가스 연료에 대해, 공기 분리장치와의 다양한 연계 설계 조건에 따른 석탄가스화 복합발전 플랜트의 전체 성능, 운전 안전성 및 NOx 배출 특성들을 비교, 검토하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.281-286
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• 2006

본 연구의 목적은 차세대 대체에너지로 각광받는 풍력발전 중에서 육상발전보다 여러 가지 이점이 있는 한국형 해상풍력터빈 블레이드의 최적형상설계를 위한 알고리즘을 구현하는 것이다. 블레이드 단면 익형의 양력과 항력 분포는 XFOIL을 이용하여 예측하였다. 첫 번째 수준의 설계변수인 각각의 블레이드 지름과 축 회전수에서 익형의 공력변수들과 최소에너지손실 조건을 이용하여 두 번째 설계변수인 각 블레이드 단면에서의 시위길이와 피치각 분포를 최적화하였다. 그리고 성능결과를 바탕으로 반응면을 구성하고, 확률적 방법을 이용하여 타당성 있는 설계공간까지 첫 번째 설계변수를 이동시키고 구배최적화 기법을 통해 각각의 제약함수를 만족하면서 목적함수를 죄대로 하는 최적블레이드 형상을 구현하였다. 설계된 최적형상에 대해 탈설계점 해석을 수행하여 성능을 구하였다.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.649-654
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• 2001

This paper describes aerodynamic preliminary design performance prediction and flow analysis for centrifugal compressor of the marine middle engine turbocharger. The performance characteristics of turbocharger compressor are investigated at various operating conditions using mass flow rate and revolution speed, and computational flow analysis for impeller and diffuser at design point are performed. Preliminary design results correspond to actual compressor geometric values comparatively by applying modified slip factor. Performance prediction and flow analysis results show good agreement with experiments. Therefore, this will provide the performance prediction in preliminary design, and help to increase the design capability for optimized impeller.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.670-675
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• 2001

This paper describes aerodynamic preliminary design performance prediction and flow analysis for turbine of the marine middle engine turbocharger. The performance characteristics of turbocharger turbine are investigated at various operating conditions using mass flow rate and computational flow analysis for rotor and nozzle at design point are performed. Preliminary design results are performed by applying mean line and radial equilibrium theory. Performance prediction and flow analysis results show good agreement with experiments. From 3 dimensional flow analysis result, efficiency is 0.6% greater than design point. Therefore, this design approach is useful for preliminary design, and helps to increase the design capability for optimized rotor blade.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.15-23
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• 2008

A numerical method based on the prediction of total pressure loss of major components of the engine has been developed for prediction of the windmilling start performance of micro-turbojet engine. The start performance in on/off design region has been analysed by applying this method to predict windmilling start-able regions of the centrifugal-type engine. The results of this analysis have been validated by comparing with the test data. The effect of each design parameters on windmilling start performance has been analysed for the enlargement of start-able regions.