Fluidelastic instability study in a rotated triangular tube array subject to two-phase cross-flow. Part I: Fluid force measurements and time delay extraction |
| |
| Institution: | 1. KOCED Wind Tunnel Center, Department of Civil Engineering, Chonbuk National University, Chonju, Chonbuk, Korea;2. Bridge Engineering Team, Daelim Industrial Co. Ltd. 146-12, Susong, Jongno, Seoul, Korea;1. Department of Mathematics, Technische Universität München, Boltzmannstrasse 3, 85748 Garching, Germany;2. Department of Mathematics and Statistics, McMaster University, Hamilton L8S 4K1, Canada;1. Key Lab of Smart Prevention and Mitigation for Civil Engineering Disasters of the Ministry of Industry and Information, Harbin Institute of Technology, Harbin, 150090, China;2. Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education, Harbin Institute of Technology, Harbin, 150090, China;3. School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China;1. Department of Structures for Engineering and Architecture, University of Naples Federico II, via Claudio 21, 80125 Naples, Italy;2. Department of Informatics, Infrastructures and Sustainable Energy, University of Reggio Calabria, Via Graziella – Feo di Vito, 89122 Reggio Calabria, Italy;1. School of Engineering, Univeristy of Oviedo, Spain;2. School of Engineering, Trinity College Dublin, Ireland;1. Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou 310014, China;2. Zhejiang Academy of Special Equipment Science, Hangzhou 310020, China;3. Key Laboratory of Special Equipment Safety Testing Technology of Zhejiang Province, Hangzhou 310020, China |
| |
| Abstract: | Fluidelastic instability is a key issue in steam generator tube bundles subjected to cross-flow. The extension to two-phase flow of the existing theoretical models, developed and tested mostly for single phase flow, is investigated in this paper. The time delay is one of the key parameter for modeling fluidelastic instability, especially the damping controlled mechanism. The direct measurement of the time delay between the tube motion and the fluid force faces certain difficulties in two-phase flow since the high turbulence due to the interaction of the two components of the flow may increase the randomness of the measured force. To overcome this difficulty, an innovative method for extracting the time delay inherent to the quasi-steady model for fluidelastic instability is proposed in this study.Firstly, experimental measurements of unsteady and quasi-static fluid forces (in the lift direction) acting on a tube subjected to air–water two-phase flow were conducted. The unsteady fluid forces were measured by exciting the tube using a linear motor. These forces were measured for a wide range of void fractions, flow velocities and excitation frequencies. The experimental results showed that the unsteady fluid forces could be represented as single valued function of the reduced flow velocity. It was also found that for a given frequency, the unsteady fluid force phase was weakly dependent on the void fraction for the range of flow velocities considered.The time delay was determined by equating the unsteady fluid forces with the quasi-steady forces. The results given by this innovative method of measuring the time delay in two-phase flow were consistent with theoretical expectations. The time delay could be expressed as a linear function of the convection time and the time delay parameter was determined for void fractions ranging from 60% to 90%. |
| |
| Keywords: | Tube array Cross-flow Two-phase flow Fluidelastic instability Quasi-steady model Time delay |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
