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단상 및 이상유동 유량 계측을 위한 평균 양방향 유동 튜브 개발
윤병조(Byong-Jo Yun),강경호(Kyong-Ho Kang),어동진(Dong-Jin Euh),백원필(Won-Pil Baek) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
Average Bi-directional flow tube was suggested to measure single and two phase flow rate. Its working principle is similar with Pitot tube, however, it makes it possible to eliminate the cooling system which is normally needed to prevent from flashing in the pressure impulse line of Pitot tube when it is used in the depressurization condition. The suggested instrumentation was tested in the air-water vertical test section which has 80㎜ inner diameter and 10m length. The flow tube was installed at 120 of L/D from inlet of test section. From the test, single air and water flow rate was measured successfully. For the emasurement of two phase flow rate, Chexal drift-flux correlation was used. In the test a new correlation of momentum exchange factor was suggested. The test result shows that the suggested instrumentation using the measured void fraction and Chexal drift-flux correlation can predict the mass flow rates within 10% error of measured data.
안태환(Tae-Hwan Ahn),윤병조(Byong-Jo Yun) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
This study focused on condensation heat transfer for the separated flow in nearly horizontal pipes in which two different heat transfer mechanisms are involved. In the top of the tube inside, a new film condensation heat transfer correlation based on Nusselt analysis was proposed by means of regression analysis with experimental data to add vapor Reynolds number. In the bottom of the tube, Dittus and Boelter(1930) correlation was applied as a convective heat transfer correlation for the condensate. Reynolds numbers in both heat transfer correlations were based on actual mean velocities. The void fraction was calculated from the one-dimensional separated flow model to determine overall heat transfer coefficient as the weighted average. The closure relations for the shear stress terms in the SFM adopted single-phase based expressions and a geometric relation for the interfacial shape in the separated flows was modeled by eccentric circles to define a concave interface. Comparison with available experimental data shows a good agreement.
평균 양방향 튜브의 설계 최적화를 위한 FLUENT 코드해석
강경호(Kyong-Ho Kang),윤병조(Byong-Jo Yun),어동진(Dong-Jin Euh),백원필(Won-Pil Baek) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
Average Bi-directional flow tube was suggested to measure single and two phase flow rate. Its working principle is similar with Pitot tube, however, it makes it possible to eliminate the cooling system which is normally needed to prevent from flashing in the pressure impulse line of Pitot tube when it is used in the depressurization condition. 3-dimensional steady state flow analyses using FLUENT 5.4 code were performed to validate the application of the average bi-directional flow tube in case of water and air flow. In this study, sensitivity studies have been performed to optimize the design features of the average bi-directional flow tube which can be applied for the various experimental conditions. For Re numbers above 1000, the k values are nearly constant regardless of the Re numbers and flow types and calculation results and experimental data coincides quite well. The current FLUENT calculation results suggest that linearity of the k values in various design features of the average BDFT is highly promising, which means that it is quite reasonable to select the typical design of the average BDFT for the convenience of the experimental conditions.