分支谐振型液压脉动衰减器动态特性分析

对分支谐振型液压脉动衰减器用CFD(Computational Fluid Dynamics,计算流体动力学)分析软件进行计算,分析共振腔结构与衰减器动态特性的关系。在层流状态下,考虑流体的可压缩性,利用M序列压力信号激励,对衰减器进行CFD模拟,利用FFT(Fast Fourier Transform,快速傅立叶变换)得出其频率特性,比较了共振腔容积相同但直径和长度不同的衰减器的频率响应和插入损失;利用阶跃压力信号模拟压力冲击,比较了它们内部流场。设计了频率特性相同但共振腔容积不同的衰减器,比较了它们的性能。利用分布参数法对共振腔结构与衰减器基频的关系进行了分析。结果表明:衰减器的固有频率特性在一定程度上与共振腔的直径和长度相关,当共振腔直径-长度比小于1并逐渐减小时,衰减器基频也减小;当其大于1并逐渐增大时,衰减器的基频变化很小,因此减小共振腔直径-长度比可以减小衰减器的体积,同时保持共振频率不变。

Analyzing Dynamic Characteristics of Side-branch Resonant Hydraulic Pulsation Dampers

We computed the transient state of a side-branch resonant hydraulic pulsation damper with CFD(computational fluid dynamics) codes to analyze the relationship between its dynamic characteristics and cavity structure.Under the laminar condition,we used the M-sequence pressure signal to simulate the pressure wave that acts as boundary in order to simulate the transient state of the pulsation damper with fluid compressibility.We transformed its transient pressure sequences into its frequency characteristics through the fast Fourier transform.We compared the frequency responses of the pulsation damper and insert loss among pulsation dampers with the same cavity volume but different diameters and lengths.We simulated the pressure impact with the step pressure and showed the flow field.We designed pulsation dampers with different cavity volume,and compared their performance.We analyzed the relationship between the base frequency of the pulsation damper and the diameter-to-length ratio by using the distributive parameter model.The analysis results show that: 1) the pulsation damper′s dynamic characteristics have relations with its cavity′s diameter-to-length ratio and decrease when the ratio is less than 1 and decreasing;2) the pulsation damper′s base frequency is smaller and increases little when the ratio is larger than 1 and increasing.Therefore designers should decrease the volume of the pulsation damper that has a smaller cavity and lower diameter-to-length ratio so as to keep its resonance frequency stable.