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3.5MW급 2단 축류 증기 터빈의 설계에 따른 효율 및 성능 분석
따망 사전,박종도,정예림,김지수,박희성 한국전산유체공학회 2025 한국전산유체공학회지 Vol.30 No.2
A steam turbine is a well-known energy conversion device that transforms high pressure steam energy into the mechanical work. This mechanical work is generally used for electricity generation or to operate mechanical machinery. In this study, we developed the three-dimensional airfoils and flow paths for micro scale axial steam turbine blades adopting both one dimensional and two dimensional design techniques. The steam turbine has been designed with the objective of achieving an output power exceeding 3.5 MW and an efficiency nearly the 50%. The averaged radius of the steam turbine was set at 262.75 mm and the rotational speed of the the blades was targeted at 6000 RPM. The simulation was conducted under varying inlet operating pressure while maintaining a constant temperature. The numerical investigation result indicated that the designed steam turbine achieved a output power of approximately 3.9 MW and an efficiency of 48.45% at an operating pressure of at 47 bar.
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1.15 MW 급 수소 전소 연소기의 온도 균일성 및 NOx 농도에 대한 수치 해석적 연구
따망 사전,박희성 한국전산유체공학회 2023 한국전산유체공학회지 Vol.28 No.4
In the gas turbine industry, minimizing fossil fuel consumption and mitigating carbon emissions are paramount objectives. With the pursuit of alternative energy sources, hydrogen fuel emerges as a potential solution. Nonetheless, there are still several unresolved questions concerning the safe operation of hydrogen fuels. This study employs numerical simulations to examine the combustion characteristics and thermal emissions of hydrogen gas, focusing on the effects of varying equivalence ratios in a micro mixer combustor. This numerical study investigated the combustion characteristics and thermal emissions of hydrogen fuel, varying the equivalence ratio in a micro mixer combustor. The findings revealed that the primary recirculation zone was most pronounced when the simulation operated at all the equivalence ratios. The combustion characteristics demonstrated that stable combustion with elevated temperatures was achieved at equivalence ratios ranging from 0.7 to 1.0. Moreover, the area-averaged outlet temperature rises as the equivalence ratio increases up to 1.2. Nevertheless, the highest pattern factor was observed at an equivalence ratio of 1.0. Furthermore, at an equivalence ratio of 0.7, the NOx emission value is computed at 88.84ppm with 15% oxygen by volume. This study indicates that stable combustion of hydrogen fuel in the micro mixer combustor not only enhances the uniformity of temperature distribution but also mitigates the thermal NOx emission through the variation of equivalence ratios.
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연소기 라이너 벽의 effusion 홀 배열 설계가 연소 특성 및 냉각 효과에 미치는 영향에 대한 수치해석적 연구
사전 따망,박종도,박희성 한국유체기계학회 2025 한국유체기계학회 논문집 Vol.28 No.3
In the present study, various tangential angles of effusion hole configurations were investigated to evaluate their effects on the cooling performance and combustion characteristics of a can-type combustor model. Numerical simulations were conducted using the Reynolds stress model for turbulence modeling and the steady flamelet approach within the non-premixed combustion framework to model methane combustion. The results indicated that the effusion hole configuration with a tangential angle of 0° enhanced the liner wall cooling effectiveness by approximately 340.28%. This configuration also blocked 77.71% of the absorbed radiation flux, resulting in a 47.81% reduction in wall temperature. Furthermore, the lowest pattern factor value was observed when the liner wall was designed with effusion holes at a tangential angle of ±30°, compared to other configurations. Similarly, injecting cooling air into the combusted region through effusion holes at a tangential angle of 0° led to an approximate 20.23% reduction in thermal NOx emissions.
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유리 렌즈의 열 성형 공정 조건 도출을 위한 수치해석 연구
최재훈,따망 사전,박희성 한국정밀공학회 2024 한국정밀공학회지 Vol.41 No.3
The Glass Molding Process (GMP) produces large quantities of glass optical parts and provides the advantages of highmolding accuracy, short production cycle, low cost, and little pollution. Developments in different sectors, such as camerasand telescopes, are prompting studies on the design of aspherical optical components. Modeling heat transfer anddeformation at high temperatures are crucial aspects of studying glass because its properties are significantly influenced bytemperature-induced phase changes. In this study, temperature changes and geometric deviations of lenses were studiedwith respect to heating, pressing, and cooling times and the heat capacity of the heater used. A 3D model was designedfor the heating, pressing, and cooling steps, and heat transfer was subjected to numerical analysis considering the specificheat of glass and the temperature dependence of thermal conductivity. Lens molding temperature conditions were thenanalyzed with the heat capacity of the lens molding heating system. Lens molding conditions were derived by analyzinglens temperatures with respect to heating and cooling capacities at each process step.
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가스터빈 블레이드 막냉각 홀의 복합 형상 변화 시 열전달 특성 향상에 관한 수치해석적 연구
박찬혁,사전 따망,권화빈,최제문,박희성 한국정밀공학회 2022 한국정밀공학회지 Vol.39 No.6
Recently, film cooling has been continuously studied to increase the efficiency of gas turbines. A turbine inlet temperature increase occurs as a way to improve the efficiency. However, it is essential to improve the cooling performance of the blade surface because of the melting point of the part. In this paper, a side hole shape wherein a general cylinder hole and two auxiliary holes are combined, is proposed to improve the film cooling efficiency, and the blowing ratio was set to 0.4, 0.8, 1.2, and 2.0. When side hole was applied, the vortex interference at the hole entrance occurred less than that of the cylinder hole. That is, the flow rate of the coolant adsorbed to the surface increased to improve the cooling performance. In conclusion, compared to the cylinder hole, the cooling efficiency of the shape to which the side hole was applied was excellent, and in particular, the average area cooling efficiency with spanwisely designed side holes improved by 83%.
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가스터빈의 Sister hole 형상의 적용에 따른 막냉각 수치해석
박찬혁(Canhyeok Park),사전 따망(Sajan Tamang),권화빈(Hwabin Kwon),박희성(Heesung Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Recently, film cooling has been studied as a part of increasing the efficiency of gas turbines. In this paper, we propose a structure in which a basic hole and two sister holes are combined to improve the film cooling performance. The injection angle and compound angle of the film cooling hole are 35 degrees and 0 degrees. The blowing ratios of the main flow and the coolant flow are 0.3-2.0. Cooling performance, vortex distribution and heat transfer characteristics are analyzed using the sst-kω turbulence model of ANSYS version 21. When sister holes are applied, the eddy current interference at the hole entrance occurs less than that of a cylinder hole. That is, the cooling fluid adheres to the surface, increasing film cooling performance. In conclusion, the hole shape to which the sister holes are applied increases the cooling efficiency by 10% compared to the cylinder hole shape
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