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90° 곡관에서의 경계층 판을 이용한 열유동 환경 개선
조종재(Jongjae Cho),김귀순(Kuisoon Kim) 한국추진공학회 2012 한국추진공학회지 Vol.16 No.1
An endwall boundary layer fence technique was adapted to improve the aerothermal environment of a gas turbine passage. The shape optimization of the fence was performed to maximize the improvement. The turbine passage was simulated by a 90° turning duct (ReD=360,000). The main purpose of the present investigation was to focus on finding a endwall boundary layer fence with minimum total pressure loss in the passage and heat transfer coefficient on the endwall of the duct. Anothor objective function was to minimize the area on the endwall of the duct. An approximate optimization method was used for the investigation to secure the computational efficiency. Results indicated that a significant improvement in aerodynamic environment can be achieved through the application of the fence. Improvement of the thermal environment was smaller than that of the aerodynamic enviroment.
90° 곡관에서의 비축대칭 끝벽면을 이용한 열유동 환경 개선
조종재(Jongjae Cho),김귀순(Kuisoon Kim) 한국추진공학회 2011 한국추진공학회지 Vol.15 No.4
This paper presents the shape optimization of the endwall which improve the aerothermal environment of a gas turbine passage. A nonaxisymmetric endwall technique was adapted as the improving method. The turbine passage was simulated by a 90° turning duct (Re<SUB>D</SUB>=360,000). The main purpose of the present investigation was to focus on finding a nonaxisymmetric endwall with minimum total pressure loss in the passage and heat transfer coefficient on the endwall of the duct. An approximate optimization method was used for the investigation to secure the computational efficiency. Results indicated that a significant improvement in aerothermal environment can be achieved through the application of a nonaxisymmetric endwall.
초음속 충동형 터빈 성능개선을 위한 동익 오버랩 최적설계
조종재(Jongjae Cho),서종철(Jongchul Seo),김귀순(Kuisoon Kim) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.11
동익 오버랩은 축류 터빈의 성능향상을 위해 적용되며, 동익의 익단과 익근에 추가적인 높이를 적용함으로써 충분한 유로를 확보할 수 있다. 특히, 초음속 터빈에서는 동익 유로에서의 질식 가능성을 줄이며, 설계 압력비를 구현할 수 있도록 한다. 하지만 동익 오버랩을 적용하면, 펌핑손실, 확산손실 등의 추가적인 손실이 동반된다. 따라서 터빈 성능향상을 최대화하기 위해 최적화 기법을 적용하였으며, 최적화 과정의 효율성을 위해 근사 최적화 기법을 사용하였다. 설계변수는 동익 오버랩의 형상변수이다. 연구결과를 통해, 최적화된 동익 오버랩에 의한 상당한 터빈 성능향상을 확인할 수 있었다. A rotor overlap technique was adapted to improve the performance of a axial turbine. The technique secured sufficient flow passage by additional height at the rotor tip and hub. especially in a supersonic turbine, the technique reduced the chance of chocking in the rotor passage, and made to be satisfied the design pressure ratio. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, a optimization technique was appled to maximize the improvement of the turbine performance. An approximate optimization method was used for the investigation to secure the computational efficiency. The design variables was shape factors of a rotor overlap. Results indicated that a significant improvement in turbine performance can be achieved through the optimization of the rotor overlap.
날개-평판 접합부에서의 날개 앞전 형상 최적화를 통한 유동특성 향상
조종재(Jongjae Cho),김귀순(Kuisoon Kim) 한국추진공학회 2009 한국추진공학회지 Vol.13 No.6
The present study deals with the optimization of the leading edge shape around a wing-body junction to minimize the strength of the horseshoe vortex, which is one of the main factor generating the secondary flow losses. For this purpose, approximate optimization method is used for the optimization. The study is performed by using FLUENT™ and iSIGHT™. The total pressure coefficient for the optimized model was decreased about 9.79% compared with the baseline model.
날개-평판 접합부에서의 날개 앞전 형상 최적화를 통한 유동특성 향상
조종재(Jongjae Cho),김귀순(Kuisoon Kim) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.11
본 논문에서는 2차유동손실을 일으키는 주요 요인 중의 하나인 말굽와류의 강도를 감쇄시키기 위해 일반적인 날개 앞전의 형상을 결정하는 변수를 정하고 이를 최적화 하였다. 근사최적설계 기법을 이용 최적화를 수행하였다. 유동해석과 최적화 프로그램으로는 FLUENT<SUP>TM</SUP>과 iSIGHT<SUP>TM</SUP>를 이용하였다. 최적화 수행결과, 기준 모델의 경우보다 전압력 계수가 약 9.79% 감소하였다. The present study deals with the leading edge shape on a wing-body junction to decrease a horseshoe vortex, one of the main factors to generate the secondary flow losses. The shape of leading-edge is optimized with design variables form the leading-edge shape. Approximate optimization design method is used for the optimization. The study is investigated using FLUENT<SUP>TM</SUP> and iSIGHT<SUP>TM</SUP>. As the result, total pressure coefficient of the optimized design case was decreased about 9.79% compare to the baseline case.
단순 날개-몸체 접합부에서의 앞전 모서리 홈에 의한 말굽와류 제어
조종재(Jongjae Cho),김귀순(Kuisoon Kim) 한국추진공학회 2009 한국추진공학회지 Vol.13 No.2
Secondary flow losses can be as high as 30~50% of the total aerodynamic losses for a turbo-machinery blade or stator row. These are important part for improving a turbine efficiency. Therefore, many studies have been performed to decrease the secondary flow losses. The present study deals with the chamfered leading-edge at a generic wing-body junction to decrease the horseshoe vortex, one of factors to generate the secondary flow losses, and investigates the vortex generation and the characteristics of the horseshoe vortex with the chamfered height, and depth of the chamfer by using FLUENTTM. It was found that the total pressure loss for the best case can be decreased about 1.55% compare to the baseline case.
90° 곡관에서의 비축대칭 끝벽과 끝벽 경계층 판을 이용한 유동특성 향상
조종재(Jongjae Cho),김상조(Sangjo Kim),서종철(Jongchul Seo),김귀순(Kuisoon Kim),정은환(Eunhwan Jeong) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.5
본 논문에서는 가스터빈 유로의 공력열환경을 개선시키기 위해서 비축대칭 끝벽과 끝벽 경계층 판의 형상 최적화를 수행하였다. 터빈 유로 모사를 위해 90° 곡관을 이용하였다. 본 연구는 터빈 유로에서의 전압력 손실과 유로 끝벽에서의 열전달 계수를 최소화하기 위한 비축대칭 끝벽과 끝벽 경계층 판의 형상을 찾는 것이다. 최적화 과정의 효율성을 위해 근사 최적화 방식을 사용하였다. 최적화된 비축대칭 끝벽과 끝벽 경계층 판을 통해, 상당한 공력열환경 개선을 확인할 수 있었다. This paper presents the shape optimization of a nonaxisymmetric endwall and endwall boundary layer fence which improve the aerothermal environment of a gas turbine passage. The endwall and fence methods were used simultaneously. The turbine passage was simulated by a 90° turning duct (ReD=360,000). The main purpose of the present investigation was to focus on finding a nonaxisymmetric endwall and boundary layer fence with minimum total pressure loss in the passage and heat transfer coefficient on the endwall of the duct. An approximate optimization method was used for the investigation to secure the computational efficiency. Results indicated that a significant improvement in aerothermal environment can be achieved through the application of a nonaxisymmetric endwall and boundary layer fence.
최적화 기법을 이용한 일반적인 날개 형상에서의 유동특성 향상
조종재(Jongjae Cho),김귀순(Kuisoon Kim) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.5
터빈 익렬 내의 2차유동손실은 터빈 익렬에서 발생하는 전체 공기역학적 손실의 30∼50% 차지한다. 따라서 터빈 효율 향상에 있어 개선해야 될 중요한 부분으로 인식되고 있다. 또한, 과거부터 2차유동에 의한 손실을 줄이기 위한 많은 연구들이 수행되어졌다. 본 논문에서는 2차유동손실을 일으키는 요인 중의 하나인 말굽와류의 강도를 감쇄시키기 위해 일반적인 날개 앞전에 설치한 판에 대해, 판의 설치 높이, 길이, 폭 및 두께 등의 형상변수를 설계변수로 정하여 이를 최적화 하였다. 연구를 위해 FLUENT<SUP>TM</SUP>와 iSIGHT<SUP>TM</SUP>를 이용하였다. 그리고 기준 모델의 경우보다 전압력 손실 계수가 약 7.5% 향상 되었다. Secondary flow losses can be as high as 30~50% of the total aerodynamic losses generated in the cascade of a turbine. Therefore, these are important part for improving a turbine efficiency. As well, many studies have been performed to decrease the secondary flow losses. The present study deals with the leading edge fences on a wing-body to decrease a horseshoe vortex, one of the factors to generate the secondary flow losses, and optimizes the shape of leading-edge fence with the shape factors, such as the installed height, length, width, and thickness of the fence as the design variables. The study was investigated using FLUENT<SUP>TM</SUP> and iSIGHT<SUP>TM</SUP>. Total pressure loss coefficient was improved about 7.5 % than the baseline case.