• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.97-104
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• 2005

A simple but efficient grid generation technique by using the modified compressible form of stream function has been formulated. Transformation of a physical plane to a streamline plane, the Von Mises Transformation, has been widely used to solve the differential equations governing flow phenomena, however, limitation arises in low velocity region of boundary layer, mixing layer and wake region where the relatively large grid spacing is inevitable. Modified Von Mises Transformation with simple mathematical adjustment for the stream function is suggested and applied to solve the confined coaxial turbulent jet mixing with simple $\kappa-\epsilon$ turbulence model. Comparison with several experimental data of axial mean velocity, turbulent kinetic energy, and Reynolds shear stress distribution shows quite good agreement in the mixing layer except in the centerline where the turbulent kinetic energy distributions were somewhat under estimated. This formulation is strongly suggested to be utilized specially for free turbulent mixing layers in axisymmetric flow conditions such as the investigation of mixing behavior, jet noise production and reduction for Turbofan engines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.222-226
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• 2006

The purpose of this study is to analyze both the design and off design performance simulation of the PW206C turbo shaft engine used in the development of the smart UAV (Unmanned Ariel Vehicle) by KARI(Korean Aerospace Research Institute). Its mainly aims to investigate performance behavior at the un-installed and installed conditions. The ways employed to be able to analyze the performance extensively were mainly carried out by comparison of performance simulation results from both the commercial program 'GASTURB 9' using compressor maps generated by Genetic algorithms (GAs) or Scaling Method, and the engine manufacturer's program 'EEPP'. Off-design performance analysis was performed through matching of both mass flow and work between engine components. The set of performance simulations of the developed analytical models was performed by a commercial program package (GASTURB 9) that provides great flexibility in the choice of independent variables of the overall system. The results from the simulations are used to compare turbo shaft engine (PW206C) performance data obtained by the EEPP. At un-installed condition, it was found that the results with the compressor map generated by GAs were relatively agreed well than those with the compressor map generated by the Scaling Method. The performance calculation results using the compressor map generated by GAs were compared at un-installed condition and installed conditions with ECS-off and ECS-Max in variation of altitude, gas generator speed and flight speed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.106-109
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• 2006

The purpose of this study is to analyze the installed performance of the PW206C turbo shaft engine used in the development of the smart UAV(Unmanned Ariel Vehicle) by KARI(Korean Aerospace Research Institute). It mainly aims to investigate performance behavior at installed conditions using both inlet and exhaust losses generated by CFD analysis of the ducts. The ways employed to be able to analyze the performance extensively were mainly rallied out by performing design point analysis of the engine where the performance simulation results from the commercial program 'GASTURB 9' used for simulation were used as inlet boundary condition for the ducts in CFD program The use of CFD tool involve modeling of the ducts to conform with the stipulated shape and sizes as defined by KARI with a grid density that allows reasonable flow characteristics applicable to aircraft components. Respective values of Shaft horse power obtained by varying flight Mach number, Gas generator RPM and Altitude considering several losses inclusive of those estimated by use of CFD tool were then plotted at three conditions with the ECS-OFF, ECS-MAX and at un-installed condition. Reasonable results were obtained as a result of using computational fluid dynamics that can hence be justified as an alternative tool for use in future flow analysis of engine and components.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.149-153
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• 2005

In order to estimate the gas turbine engine performance precisely, the component maps containing their own performance characteristics should be needed. In this study a component map generation method which may identify compressor map conversely from a performance deck provided by engine manufacturer using genetic algorithms was newly proposed. As a demonstration example for this study, the PW 206C turbo shaft engine for the tilt rotor type Smart UAV (Unmanned Aerial Vehicle). In ordo to verify the proposed method, steady-state performance analysis results using the newly generated compressor map was compared with them performed by EEPP(Estimated Engine Performance Program) deck provided by engine manufacturer. And also the performance results using the identified maps were compared with them using the traditional scaling method. In this investigation, it was found that the newly proposed map generation method would be more effective than the traditional scaling method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.253-256
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• 2009

In the micro turbojet engine less than 350kw power class, it is not easy to find out the good atomization fuel injector with good spray quality. However conceptually, rotating fuel injection system can give high atomization quality by only the centrifugal force of a high speed rotating shaft of the engine without high-pressure fuel pump. With this motivation, we manufactured very small rotating fuel injector of 40 mm diameter and performed under a variety of injection orifices. We measured droplet size, velocity and spray distribution by the PDPA(Phase Doppler Particle Analyzer) system. Also spray was visualized by using high speed camera. From the test results, we could understand that the length of liquid column from the injection orifice is mainly controlled by the rotational speeds. Furthermore, droplet size(SMD) is decreased with the rotational speeds and is influenced by the diameter of the injection orifice and liquid film thickness.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.81-88
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• 2005

In order to estimate the gas turbine engine performance precisely, the component maps containing their own performance characteristics should be needed. In this study a component map generation method which may identify compressor map conversely from a performance deck provided by engine manufacturer using genetic algorithms was newly proposed. As a demonstration example for this study, the PW 206C turbo shaft engine for the tilt rotor type Smart UAV(Unmanned Aerial Vehicle). In order to verify the proposed method, steady-state performance analysis results using the newly generated compressor map was compared with them performed by EEPP(Estimated Engine Performance Program) deck provided by engine manufacturer. And also the performance results using the identified maps were compared with them using the traditional scaling method. When the performance analysis is performed at far away operation conditions from the design point, in case of use of e component map by the traditional scaling method, the error of the performance analysis results is greatly increasing. In the other hand, if in case of use of the compressor map generated by the proposed GAs scheme, the performance analysis results are closely met with those by the performance deck, EEPP.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.14-14
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• 1999

비활성 가스제너레이터는 가스터빈 추진기관 및 기타 열기관을 이용하여 연소가 되지 않는 저온의 공기를 생산하는 기계장치를 말하며 이러한 저온의 비활성 기체를 화재 지역에 분사하는 경우 기존의 소방수를 이용한 화재 진압방식보다 매우 효율적으로 화재진압에 사용되어 질 수 있다. 일반적으로 민항기 등의 가스터빈 추진 기관에서 배기되는 기체내에는 터빈입구온도(TIT : Turbine Inlet Temperature)및 초과공기지수(Excess Air Coefficient)에 따라 다르게 나타나지만 TIT가 1500$^{\circ}$K인 경우 약 13-14%정도의 산소가 잔존하는 것으로 알려져 있다. 따라서 본 연구에서는 가스터빈 및 열교환 시스템 그리고 터빈 1단 등의 시스템 조합율을 통하여 대기 중의 기체의 온도를 영하 2$0^{\circ}C$ 및 산소함유량을 약 5%수준까지 낮춤으로서 이를 대형 화재 진압에 사용하기 위한 연구이다. 비활성 가스제너레이터에 사용하는 연료로는 Kerosene 및 CNG(Compressed Natural Gas)등이 사용될 수 있으며, 유량이 8.1kg/sec인 터보축 가스터빈 엔진을 사용하는 경우 18750㎥ 부피의 비활성기체를 생산하는데 Kerosene 연료가 약 1톤(200＄ 이하)이 필요한 것으로 계산되며 이에 소요되는 시간도 약 52분에 지나지 않는 것으로 계산되었다. 만일 50kg/sec의 보다 큰 가스터빈 엔진을 사용하는 경우 약 9분 정도가 필요한 것으로 계산되었다. 사용되는 가스터빈은 압축비가 15, 열교환기의 효율이 $\varepsilon$=0. 그리고 최종 터빈 1단의 팽창비가 1.25가 적합한 것으로 계산된다. 연구 분석 결과 기술적 문제점으로는 배기 가스온도가 낮은데 따른 출구 부분의 Bearing, Sealing이 문제가 될 수 있다고 판단되며 배기 가스 자체에 대기 공기중에 함유되어 있던 습기가 얼어붙는(Icing화) 문제가 발생하기 때문에 배기가스의 Icing을 방지하기 위하여 압축기 끝단에서 공기를 추출하여 배기부분에 송출할 필요성이 있는 것으로 판단되었다. 출구가스의 기체 유동속도가 매우 빠르므로 (100-l10m.sec) 이를 완화하기 위한 디퓨저의 설계가 요구된다고 판단된다. 또 연소기 후방에 물을 주입하는 경우 열교환기 및 기타 부분품에 발생할 수 있는 부식 및 열교환 효율 저하도 간과할 수 없는 문제로 파악되었다. 이러한 기술적 문제가 적절히 해결되는 경우 비활성 가스 제너레이터는 민수용으로는 대형 빌딩, 산림, 유조선 등의 화재에 매우 적절히 사용되어 질 수 있을 뿐 아니라 군사적으로도 군사작전 중 및 공군 기지의 화재 그리고 지하벙커에 설치되어 있는 고급 첨단 군사 장비 등의 화재 뿐 아니라 대간첩작전 등에 효과적으로 활용될 수 있을 것으로 판단된다.