Читать книгу Flow-Induced Vibration Handbook for Nuclear and Process Equipment - Группа авторов - Страница 27

For complex components such as nuclear steam generators and power condensers, a comprehensive three‐dimensional thermalhydraulic analysis is required. In such analyses, the component is divided into a large number of control volumes. The equations of energy, momentum and continuity are solved for each control volume. This is done with numerical methods using a computer code such as the THIRST code for steam generators (Pietralik, 1995). The numerical grid outlining the control volumes for the analysis of a typical steam generator is shown in Fig. 2-2. The grid must be sufficiently fine to accurately predict the flow distribution along the tube. Some typical thermalhydraulic analysis results are shown in Fig. 2-3 for the U‐bend region of a steam generator. For flow‐induced vibration analyses, the results must be in the form of pitch flow velocity and fluid density distributions along a given tube. These distributions constitute the input to a flow‐induced vibration analysis of this particular tube. Figure 2-4 shows pitch flow velocity and fluid density distributions for an example condenser tube.

Fig. 2-3 Flow Velocity Vectors in the Central Plane of a Typical Steam Generator U‐Bend Region.

Fig. 2-4 Gap Cross‐Flow Distribution Along a Typical Condenser Tube.

Fig. 2-5 Flow Pattern Map for Two‐Phase Flow Across Cylinder Arrays Using Flow Pattern Boundaries (Grant and Chisholm (1979) and Axes Parameters from McNaught (1982)).