| 1. |
- Ma, Y., et al.
(författare)
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Theoretical research on flow instability in parallel channels under motion conditions
- 2013
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Ingår i: Proceedings of the 21st International Conference on Nuclear Engineering --2013. - : ASME Press. - 9780791855812
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Konferensbidrag (refereegranskat)abstract
- In motion conditions, in addition to gravitational acceleration, a new acceleration was developed and it was added to the thermal hydraulics characteristics in flow channels. The additional acceleration leads to the different thermal hydraulic characteristics and will trigger the flow oscillation and even flow instability in parallel channels. In order to study the effect of the additional acceleration on the flow oscillation, the corresponding physical models are established in this work. Through the deduction of the mathematical model, the code for flow instability under motion conditions with Gear algorithm is developed. The flow oscillation curves, critical power, marginal stability boundary (MSB) are obtained. After comparison and analysis, it is found that some motion conditions lead to flow periodic oscillation. Different flow passage position results in different oscillation amplitudes. The marginal stability boundaries (MSB) under different motion conditions fit well, that is, the effect of motion conditions on MSB is small. Number of channels has little effect; however, channel arrangement influences the flow in every channel. These conclusions are of great significance in marine reactor design.
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| 2. |
- Xing, M., et al.
(författare)
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Validation of trace code against ROSA/LSTF test for SBLOCA of pressure vessel upper-head small break
- 2014
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Ingår i: 2013 21st International Conference on Nuclear Engineering, ICONE 2013. - : ASME Press. - 9780791855812
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Konferensbidrag (refereegranskat)abstract
- OECD/NEA ROSA/LSTF project tests are performed on the Large Scale Test Facility (LSTF). LSTF is a full-height, fullpressure and 1/48 volumetrically-scaled two-loop system which aims to simulate Japanese Tsuruga-2 Westinghouse-type 4-loop PWR. ROSA-V Test 6-1 simulates a pressure vessel (PV) upper-head small break loss-of-coolant accident (SBLOCA) with a break size equivalent to 1.9% of the volumetrically scaled cross-sectional area of the reference PWR cold leg. By building a TRACE calculation model of LSTF and PV upper-head, the paper dedicated to assess the effect of different modeling options and parameters on simulating thermal hydraulic behaviors of TRACE code. The results show that TRACE code well reproduce the physical phenomena involved in this type of SBLOCA scenarios. Almost all the events in the experiment are well predicted by the model based on TRACE code. In addition, the sensitivity of different models and parameters are investigated. For example, the code slightly overestimated the break mass flow from upper head which could affect the accuracy of the results significantly. The rising of core exit temperature (CET) is significantly influenced by the bypass flow area between downcomer and hot leg.
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| 3. |
- Zhang, Youjia, et al.
(författare)
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An experimental study on liquid film dynamics and interfacial wave of air-water two-phase flow in a horizontal channel
- 2013
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Ingår i: 2013 21st International Conference on Nuclear Engineering, ICONE 2013. - : ASME Press. - 9780791855812
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Konferensbidrag (refereegranskat)abstract
- This study is concerned with liquid film dynamics and stability of annular flow, which plays an important role in understanding film rupture and dryout in boiling heat transfer. The research work starts from designing and making a test facility which enables the visualization and measurement of liquid film dynamics. A confocal optical sensor is applied to track the evolution of film thickness. A horizontal rectangular channel made of glass is used as the test section. Deionized water and air are supplied into that channel in such a way that an initial stratified flow forms, with the liquid film on the bottom wall. The present study is focused on characterization of liquid film profile and dynamics in term of interfacial wave and shear force induced film rupture under adiabatic condition. Based on the experimental data and analysis, it is found that given a constant water flowrate, the average thickness of water film decreases with increasing air flowrate, while the interfacial wave of the two-phase flow is intensified. As the air flowrate reaches a critical value, a localized rupture of the water film occurs.
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