液体火箭发动机充液导管流固耦合动力学特性

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

为了深入研究流固耦合(FSI)作用对液体火箭发动机充液导管频率特性的影响,采用传递矩阵法(TMM)建立了空间导管流固耦合动力学计算模型.针对真实发动机导管开展了传递矩阵模型与传统基于附加质量的有限元(FEM)(非耦合)模型仿真计算以及模态试验验证,比较了管径、壁厚等结构参数对导管流固耦合作用的影响.结果表明:在流固耦合作用下,导管各阶谐振频率减小、而对应的流体振荡与结构振动幅值增大.管径对导管低阶频率特性的影响较壁厚对其影响更大.对于该算例,当管径大于设计值30%后,耦合作用引起的1阶频率误差高于10%,此时流固耦合不能忽略;而壁厚对1阶谐振频率的影响则小于8%.

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.