Study on temperature distribution and fluid-thermal-structural coupling analysis of the subsea pipeline connector sealing structure based on equivalent stepped hollow cylinder model

During the operation of the subsea pipeline connector (SPC), its sealing structure is subjected to the combined effects of internal high-pressure and high-temperature (HPHT) fluid, external low-temperature fluid and pre-tightening force. Therefore, the temperature distribution, the equivalent stress and the contact pressure of the sealing structure are the results of the coupling of flow, heat transfer and stress. However, the traditional thermal-structural coupling method ignores the influence of internal and external flow fields and conducts numerical simulations by assuming that the temperature of the inner surface of the sealing structure is equal to that of the internal HPHT fluid. This is far from the actual situation. According to the structural characteristics of the sealing structure, this study proposed an equivalent stepped hollow cylinder model, and further obtained the equivalent thermal circuit and radial temperature distribution functions. The computational fluid dynamics software Fluent was used to perform fluid-thermal simulations to obtain the temperature distribution of the sealing structure, and the proposed radial temperature distribution functions were verified, with the maximum temperature deviation not exceeding 9 K. Then, based on the obtained temperature field, coupled with the structural field, the equivalent stress and the contact pressure of the sealing structure were analyzed. Furthermore, the fluid-thermal-structural coupling method is compared with the traditional method. Finally, the pressure and temperature cycle test and field deployment were carried out on the SPC. The result show that it is feasible to obtain the sealing performance of the sealing structure using the fluid-thermal-structural coupling method.