Calculation of Natural Frequency and Added Mass Coefficient of Spatial Bend Tube Bundle

It is a crucial step for the safe and stable operation of the intermediate heat exchanger to determine the reasonable values of natural frequencies and added mass coefficients of the spatial bend tubes during the engineering design process. This work aims to calculate the natural frequencies and added mass coefficients of the concentric spatial bend tubes of the intermediate heat exchanger in air and liquid sodium by finite element method. The concentric tube bundle was divided into three typical areas. For these typical areas, three-dimensional models of heat exchanger tubes and fluid fields were built to calculate the natural frequencies and added mass coefficients at six places. The results show that the natural frequency of the heat transfer tubes in the air is less affected by the bending radius of the spatial bend tube, while the added mass coefficient is greatly affected by the bending radius of the spatial bend tube and the place in which it is located. The tubes located in the approximate triangular arrangement place have the lowest natural frequency and the highest added mass coefficient. (authors)