Analysis Of The Influence Of Flexible Pipe Arrangement And Performance Parameters On Pipeline Vibration Transfer Characteristic

The pipeline system is the main source of vibration and noise generated by ships.As an important component of controlling pipeline vibration and noise,flexible pipes are the main means to reduce the transmission of pipeline system vibration and noise.However,in practical engineering applications,the phenomenon of poor or negative isolation effect of flexible nozzles often occurs,especially in the mid to low frequency range.In the actual installation process,due to the limitations of the installation space on board,the installation method of flexible pipes often cannot achieve the best vibration isolation performance.Therefore,selecting a reasonable installation and layout method for flexible nozzles and pipe sections to maximize the vibration isolation effect has important engineering application value.In response to the issue of poor isolation effect of flexible connecting pipes after installation on a real ship,this article takes the outlet pipeline system of a certain pump as the object,establishes a three-dimensional model of the outlet pipeline based on ANSYS finite element numerical simulation method,calculates the excitation force caused by fluid pressure pulsation and unbalanced equipment,and establishes a bidirectional fluid solid coupling simulation process.At the same time,the fluid excitation force and mechanical excitation force are loaded into the finite element pipeline model,Calculate the acceleration response and self power spectrum of fluid structure coupling vibration in the pipeline system.By changing the installation length,position,and form of the flexible nozzle,analyze the variation law of the vibration level drop at both ends of the flexible nozzle and the total vibration level of the downstream monitoring points of the pipeline.For the common laws discovered through multiple sets of finite element simulations,a land test bench was built to conduct comparative tests on the vibration characteristics of pipeline systems under different installation conditions of flexible nozzles.The pipeline vibration was measured under pump conditions,and the finite element method calculation results were verified.The layout plan of flexible nozzles on the pipeline system was explored to improve the vibration isolation effect of flexible nozzles.The research results indicate that(1)lengthening the flexible nozzle is beneficial for improving the vibration level of pipeline attenuation,but its effect on low-frequency vibration attenuation is limited;(2)The installation position of the flexible connecting pipe has a significant impact on the low-frequency line spectrum vibration of the pipeline,and changing the layout position can improve the line spectrum vibration isolation effect of the pipeline system;(3)The elbow shaped pipe has a certain vibration isolation effect,and in some cases where installation space is limited,elbow shaped pipes can be considered to replace bent pipes.The research conclusion has reference and guiding significance for improving the low-frequency vibration isolation effect of flexible nozzles and reducing vibration transmission in pipeline systems.