Fluid-structure coupled vibration characteristics analysis of a high-pressure fuel pipe

Abnormal vibration is one of the primary causes of high-pressure fuel pipe failure. To investigate the vibration characteristics of a high-pressure fuel pipe under combined diesel engine excitation and fuel pressure pulsation, a two-way fluid–structure interaction (FSI) model was established. A comparative analysis of the dry and wet modal characteristics was first performed. Based on the prescribed diesel engine vibration displacement, the vibration responses of the high-pressure fuel pipe with and without diesel engine excitation were compared. Furthermore, the effects of different engine loads (50 %, 75 %, and 100 %) and inlet pressure levels (36, 38, 40, 42, and 44 MPa) on the vibration energy distribution were investigated through spectral analysis. The results show that the natural frequencies of the high-pressure fuel pipe decrease under fluid-structure interaction, with the frequency reduction becoming more pronounced in higher-order modes. When diesel engine excitation is considered, the peak vibration displacement decreases slightly, while the vibration attenuation rate decreases, resulting in a longer vibration response duration. As the engine load increases, the vibration displacement increases, and the spectral components near the second and fourth wet modal frequencies become more pronounced under the full-load condition. Increasing the inlet pressure also leads to a progressive increase in the spectral amplitude, particularly near the fourth wet modal frequency. These findings provide theoretical support for vibration assessment and structural optimization of marine high-pressure fuel pipes.