• Nuclear Engineering and Technology
• /
• 제51권5호
• /
• pp.1279-1288
• /
• 2019

The vortex-type fluidic diode (FD) is a key safety component for inherent safety in various advanced reactors such as the sodium fast reactor (SFR) and the molten salt reactor (MSR). In this study, topology optimization is conducted to optimize the design of the vortex-type fluidic diode. The optimization domain is simplified to 2-dimensional geometry for a tangential port and chamber. As a result, a design with a circular chamber and a restrictor at the tangential port is obtained. To verify the new design, experimental study and computational fluid dynamics (CFD) analysis were conducted for inlet Reynolds numbers between 2000 and 6000. However, the results show that the performance of the new design is no better than the original reference design. To analyze the cause of this result, detailed analysis is performed on the velocity and pressure field using flow visualization experiments and 3-D CFD analysis. The results show that the discrepancy between the optimization results in 2-D and the experimental results in 3-D originated from exclusion of an important pressure loss contributor in the optimization process. This study also concludes that the junction design of the axial port and chamber offers potential for improvement of fluidic diode performance.

• 한국유체기계학회 논문집
• /
• 제20권1호
• /
• pp.29-34
• /
• 2017

An analysis on pressure drop in vortex amplifier has been performed. Based on theoretical approach with flow physics on well-known firm ground from previous studies, two dimensional flow model, which is very useful to calculate pressure drop of vortex amplifier, is proposed. Parametric studies on inlet and outlet boundary conditions also have been performed so that it found the most influential parameter is the inlet swirl velocity condition. Finally, a simple formulation is given to calculate total pressure drop.

• 한국가시화정보학회지
• /
• 제6권2호
• /
• pp.14-19
• /
• 2008

In this paper, the recirculation flow motion and mixing characteristics driven by air bubble flow in a rectangular water tank is studied. The Time-resolved PIV technique is adopted for the quantitative visualization and analysis. 532 nm Diode CW laser is used for illumination and orange fluorescent particle images are acquired by a PCO 10bit high-speed camera. To obtain clean particle images, 545 nm long pass optical filter and an image intensifier are employed and the flow rates of compressed air is changed from 2 l/min to 4 l/min at 0.5 MPa. The recirculation and mixing flow field is further investigated by the POD analysis technique. It is observed that the large scale counterclockwise rotation and main vortex is generated in the upper half depth from the free surface and one quarter width from the sidewall. When the flow rates are increased, the main vortex core is moved to the side and bottom wall direction.

• 한국음향학회지
• /
• 제38권2호
• /
• pp.222-230
• /
• 2019

본 논문에서는 유체의 와류 현상을 이용한 에너지 하베스팅 회로의 전력을 분석하였다. 와류를 전기 에너지로 바꾸기 위한 소자로 PVDF(Polyvinylidene fluoride) 압전 센서를 사용하였으며, 전력 분석을 위해 잘 알려진 브리지 다이오드 정류 회로와 전력 변환 효율을 향상시키기 위해 다이오드 정류회로 입력단에 병렬 동기 스위치 회로를 접목한 P-SSHI(Parallel Synchronized Switch Harvesting on Inductor) 정류 회로를 사용하였다. 다이오드 및 P-SSHI 정류 회로의 출력 전력은 이론을 통해 분석하였고 실험을 통해 검증하였다. 공기에 의한 와류를 이용한 실험을 통해 P-SSHI 정류 회로의 전력효율이 69 % 증가됨을 확인하였다. 또한 수확된 와류 에너지를 슈퍼 커패시터에 저장하는 회로를 구현하여 2차 전지로써 활용이 가능함을 확인하였다.