Floating raft equipment (FRE) isolation is an effective measure to control mechanical noise of ships in vibration transfer path. Based on the admittance principle, a dynamic simulation model of the equipment, floating-raft and foundation system was developed. The vibration isolation performance of the floating-raft was analyzed, and the vibration isolation effect was compared with that of the double-stage vibration isolation equipment (DSE). Numerical simulation was carried out for a small FRE used in a pump unit. The results show that in medium and high frequency range the vibration isolation efficiency mainly depends on the natural frequency of the equipment and upper-stage vibration isolatorω1 and that of the raft and lower-stage vibration isolatorω2. Thus, the efficiencies of FRE and DSE with the sameω1 andω2 are almost identical. However, the effectiveness of FRE is a little better than that of DSE at low frequencies. Simulation results also show that the phase differences between excitations from the equipment on the raft have little influences on the performance of the FRE at medium and high frequencies, but have relatively distinct influences at low frequencies.%浮筏隔振是从传递路径上控制舰艇机械噪声的重要措施之一.为分析浮筏隔振装置的性能及筏架上设备激励相位差的影响,并与双层隔振装置的效果进行对比,本文基于导纳理论建立了设备-浮筏-安装基座系统的动力学分析模型,对泵组小型浮筏隔振装置进行了数值计算与分析.结果表明,在中高频段,浮筏隔振装置的效果主要取决于设备-上层隔振器、筏架-下层隔振器系统的垂向刚体振动固有频率ω1、ω2,故筏架上单台设备运行时其隔振效果与同固有频率ω1、ω2的双层隔振装置基本一致,而在低频段浮筏隔振装置效果略好;筏架上设备激励的相位差对中高频段传递到基座的振动功率流及振级落差几乎没有影响,但对低频段的振动传递及隔振性能有一定影响.
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