汽车空调低压管路流固耦合振动特性分析

Fluid structure interaction vibration characteristics of the low pressure pipeline of an automotive air conditioning system

汽车空调管路的振动与噪声直接影响车内舒适度。基于计算流体力学和结构有限元的流固耦合方法分析了某型汽车空调低压管路系统在制冷剂作用下的振动特性;建立低压管路系统的有限元模型,进行空管模态分析和流体作用下的预应力模态分析,针对橡胶管结构采用分层建模方法进行模态试验验证;使用流体动力学方法分析了制冷剂的流场特性,获取管壁压力,进行流固耦合作用下的管路振动特性分析,分析了流体脉动频率和橡胶管硬度对流致振动特性的影响。结果表明:空调低压管路的模态表现为低频振动的特点,且模态振型主要体现在橡胶管上;考虑制冷剂与管路的流固耦合作用后,模态固有频率增大,最大增加43.83%;靠近压缩机的橡胶管在脉动压力激励下表现出周期性的振动,远离压缩机的橡胶管振动逐渐衰减;管道应力与压缩机工作频率成正相关关系,管道振动位移随着橡胶管硬度增大而减小。

The noise and vibration of automotive air conditioning pipelines directly affect the interior comfort.Based on the fluid structure interaction principle in computational fluid dynamics and the structural finite element method,the vibration of the low pressure pipeline system of an automotive air conditioner caused by refrigerant flow was analyzed.The finite element model of the low pressure pipeline system was established,and the modal analysis of the pipe under fluid action in empty and pre-stressed states were carried out,the layered modeling method was adopted for the structural analysis of the rubber hose,and corresponding modal tests verified the numerical results.The fluid dynamics method was used to analyze the flow field characteristics of the refrigerant to obtain,the pipe wall pressure so as to analyze the pipeline vibration characteristics under the fluid structure interaction.The influences of the fluid pulsation frequency and rubber hose hardness on convection-induced vibration characteristics was analyzed.The results show that:the modes of the air conditioning low pressure pipeline are characterized by low-frequency vibration,and the modal vibration mode is mainly reflected on the soft rubber hose;after considering the fluid structure interaction between refrigerant and pipeline,the natural frequency increases,with a maximum growth rate of 43.83%;the rubber hose near the compressor exhibits periodic vibration under the excitation of pulsating pressure,while the vibration of the rubber hose far away from the compressor attenuates gradually;the pipeline stress is positively correlated with the compressor working frequency,and the vibration displacement of the pipeline decreases with the increase of the hardness of the rubber hose.