A Flow-Induced Vibration Study on the Multiple Rectangular Tubes Bundles for Steam Generator Outlet Pipes of HTR-PM

The heat transfer tubes in steam generator of High Temperature Reactor-Pebble bed Modules (HTR-PM) suffer a high-speed and high temperature Helium flow environment. To avoid high thermal stress and decrease the fluid-induced vibration, tubes are packed in the form of rectangular tubes bundles. The empirical formulas of flow-induced vibration in ASME code are applicable to circular cylinder and incompressible media, which is not available for the proposed problem. In the present paper, rectangular tubes bundles are simplified as square cylinder with specific stiffness. The vibration of six square cylinders with horizontal and vertical arrangements are analyzed in displacement and frequency. The results show that the six square cylinders reveal same vibration amplitude and frequency, but different balance positions. For the horizontal arrangement and the vertical arrangement, according to the different balance positions, the balance position boundary line can be drawn. The cylinders at two sides of the balance position boundary line are closer to each other, where collisions or damages are easy to occur.