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유동가속부식으로 인한 오리피스 후단 탄소강 배관에서의 국부감육 현상에 관한 연구
조연수(Yun-Su Cho),강덕원(Deok-Won Kang),김경훈(Kyung-Hoon Kim),황경모(Kyung-Mo Hwang) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
When pipe components made of carbon steel in nuclear and industry are exposed to flowing fluid, wall thinning caused by FAC(Flow Accelerated Corrosion) can be generated and eventually ruptured. A study to identify the locations generating local wall thinning and to disclose turbulence coefficient related to the local wall thinning was performed. Experiment and numerical analyses for grade after orifice of down scaled piping components were performed. In particular, flow visualization experiment which was used alkali metallic salt was performed to find actual location of local wall thinning. The turbulence coefficients based on the numerical analyses were compared with the local wall thinning thickness. The purpose of this paper is that cause investigation of wall thinning by FAC and prediction exactly the local wall thinning location in Pipe.
배관계 오리피스 하류에서 유동가속부식으로 인한 국소 유동 파라미터에 대한 조사
김경훈(Kyung-Hoon Kim),조연수(Yun-Su Cho),김형준(Hyung-Joon Kim) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.7
In this study, the performance of an impeller according to blade length and pitch angle was studied experimentally by building a variable pitch impeller while changing blade length to review the effect of blade length and pitch angle on a fan’s performance. The pitch angle was changed in six steps from 20°~45° at intervals of 5° while the blade lengths were changed to 90 mm, 100 mm, 110 mm and 120 mm with an identical airfoil shape while carrying out the experiment. The results are summarized as follows : The air flow per static pressure of axial fans increased linearly with increase of pitch angle, but the high static pressure showed a decrease at a pitch angle of 35°. The shaft power increased proportionally to the pitch angle at all blade lengths; the larger the pitch angle, the larger the measured increase of shaft power. This is because the drag at the fan’s front increases with the pitch angle. In the axial fans considered in this research, the flow and incre.
액적충돌침식으로 인한 배관감육 예측체계 구축에 관한 연구
김경훈 ( Kyung Hoon Kim ),조연수 ( Yun Su Cho ),황경모 ( Kyeong Mo Hwang ) 한국부식방식학회(구 한국부식학회) 2013 Corrosion Science and Technology Vol.12 No.3
The most common pipe wall thinning degradation mechanisms that can occur in the steam and feedwater systems are FAC (Flow Acceleration Corrosion), cavitation, flashing, and LDIE (Liquid Droplet Impingement Erosion). Among those degradation mechanisms, FAC has been investigated by many laboratories and industries. Cavitation and flashing are also protected on the piping design phase. LDIE has mainly investigated in aviation industry and turbine blade manufactures. On the other hand, LDIE has been little studied in NPP (Nuclear Power Plant) industry. This paper presents the development of prediction system for pipe wall thinning caused by LDIE in terms of erosion rate based on air-water ratio and material. Experiment is conducted in 3 cases of air-water ratio 0.79, 1.00, and 1.72 using the three types of the materials of A106B, SS400, and A6061. The main control parameter is the air-water ratio which is defined as the volumetric ratio of water to air (0.79, 1.00, 1.72). The experiments were performed for 15 days, and the surface morphology and hardness of the materials were examined for every 5 days. Since the spraying velocity (v) of liquid droplets and their contact area (Ac) on specimens are changed according to the air-water ratio, we analyzed the behavior of LDIE for the materials. Finally, the prediction equations(i.e. erosion rate) for LDIE of the materials were determined in the range of the air-water ratio from 0 to 2%.
배관 엘보우에서 유동가속부식으로 인한 난류 속도 성분과 국부 감육의 상관관계
이상규(Sang Kyu Lee),조연수(Yun Su Cho),김경훈(Kyung Hoon Kim),황경모(Kyung Mo Hwang) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
When pipe components made of carbon steel in nuclear, fossil, and industry are exposed to flowing fluid, wall thinning caused by FAC(Flow Accelerated Corrosion) can be generated and eventually ruptured. A study to identify the locations generating local wall thinning and to disclose turbulence coefficient related to the local wall thinning was performed. Experiment and numerical analyses for elbow of down scaled piping components were performed. In particular, flow visualization experiment which was used alkali metallic salt was performed to find actual location of local wall thinning. From the comparison of the results, the vertical flow velocity component(Vr) flowing to the wall after separating in the wall due to the geometrical configuration and colliding with the wall directly at an angle of some degree was analogous to the configuration of local wall thinning.
배관 재질 손상에 미치는 액적충돌침식의 영향에 대한 연구
김경훈 ( Kyung Hoon Kim ),조연수 ( Yun Su Cho ),김형준 ( Hyung Joon Kim ) 한국분무공학회 2013 한국액체미립화학회지 Vol.18 No.1
Wall thinning of pipeline in power plants occurs mainly by flow acceleration corrosion (FAC), cavitation erosion (C/E), liquid droplet impingement erosion (LDIE). Wall thinning by FAC and C/E has been well investigated; however, LDIE in plant industries has rarely been studied due to the experimental difficulty of setting up a long injection of highly-pressurized air. In this study, we designed a long -term experimental system for LDIE and investigate the behavior of LDIE for three kinds of materials (A106b, SS400, A6061). The main control parameter was the air-water ratio (a), which was defined as the volumetric ratio of water to air (0.79, 1.00, 1.72). In order to clearly understand LDIE, the spraying velocity (v) of liquid droplets was controlled larger then 160m/s and the experiments were performed for 15 days. Therefore, this research focuses relation between erosion rate and air-water ratio on the various pipe-flow materials. Npp(nuclear power plant)`s LDIE pre-diction theory and management technique were drawn from the obtained data.
포스터 전시회 : 배관 재질 손상에 미치는 액적충돌침식의 영향에 대한 연구
김경훈 ( Kyung Hoon Kim ),최덕현 ( Duk Hyun Choi ),조연수 ( Yun Su Cho ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-
Wall thinning erosion in carbon steel piping classified FAC, C/E, LDIE mainly. FAC(Flow Acceleration Corrosion) was investigated by many labs. And, Effect of C/E(Cavitation Effect) is decreased due to design supplementation. LDIE(Liquid Droplet Impingement Erosion) is investigated in aviation industry mainly. On the other hand, LDIE is not studied in NPP(Nuclear Power Plant) industry. Therefore, this research focuses relation between erosion rate and air-water ratio, material. Experiment is conducted in 3 cases of air-water ratio(0.79, 1.00, 1.72) and 3 cases of material(A106B, SS400, A6061). LDIE threshold value and erosion rates are obtained through continuous experiment. NPP`s LDIE prediction theory and management technique were drawn from the obtained data
배관계 티에서 유동가속부식으로 인한 난류속도성분과 국부감육의 관계 규명
김경훈(Kyung Hoon Kim),이상규(Sang Kyu Lee),조연수(Yun Su Cho),황경모(Kyung Mo Hwang) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.7
When pipe components made of carbon steel in nuclear, fossil, and industry are exposed to flowing fluid, wall thinning caused by FAC(flow accelerated corrosion) can be generated and eventually ruptured at the portion of pressure boundary. A study to identify the locations generating local wall thinning and to disclose turbulence coefficient related to the local wall thinning was performed. Experiment and numerical analyses for tee of down scaled piping components were performed and the results were compared. In particular, flow visualization experiment which was used alkali metallic salt was performed to find actual location of local wall thinning inside tee components. To disclose the relationship between turbulence coefficients and local wall thinning, numerical analyses were performed for tee components. The turbulence coefficients based on the numerical analyses were compared with the local wall thinning based on the measured data. From the comparison of the results, the vertical flow velocity component(Vr) flowing to the wall after separating in the wall due to the geometrical configuration and colliding with the wall directly at an angle of some degree was analogous to the configuration of local wall thinning.