Dynamic characteristics of fluid-filled pipe in liquid rocket engines considering fluid-structure interaction

To study the influence of fluid-structure interaction (FSI) on the frequency characteristics of fluid-filled pipe in rocket engines, a dynamic characteristic model of spatial pipe was set up based on transfer matrix method(TMM). Targeting a real liquid rocket engine pipe, simulations by transfer matrix method as well as conventional finite element method (FEM) for fluid with added-mass (non-FSI) were proposed, and verification modal test was also carried out. Influences of parameters such as diameter and thickness of the pipe on the coupling effect were discussed. The results indicate that each resonant frequency declines and the corresponding amplitude increases under FSI effect. In addition, the influence of pipe thickness on low-order resonant frequencies is more significant than the pipe diameter. The example given hereto also demonstrate that the concerned 1st-order resonant frequency calculated by the non-FSI model offsets is over 10% when the pipe thickness exceeds 30% of the design value, so the coupling effect can not be ignored in this case. And the influence of pipe thickness on 1st-order resonant frequency is less than 8% within the range of calculation.