短管节流阀内流动噪声的实验研究及降噪措施

Experimental study of flow noise in short tube throttle valve and noise reduction measures

短管节流阀作为节流机构,因其结构简单而广泛应用于家用空调器中,当两相状态的制冷剂流经短管节流阀时会产生严重的噪声。设计并搭建了短管节流阀流动噪声测试台,实验研究了制冷剂流型、流量和干度对短管节流阀内流动噪声频率和声压级的影响规律,并在此基础上提出了降噪措施。实验结果表明,阀进口流型为搅浑流时产生的流动噪声声压级最大,阀进口流型为泡状流型和环状流型时产生的流动噪声较小;流动噪声的峰值频率随质量流量的增大而增大,质量流量由20 kg/h增大到80 kg/h时,流动噪声的峰值频率增大38.6%;干度由0.05增大到0.4时,流动噪声的平均声压级先增大7 dB,后减小3 dB。提出了将阀芯入口处的突扩突缩结构改为喇叭口渐缩结构的方式来实现降噪的结构优化方案,优化后的结构方案可将流动噪声的平均声压级降低2 dB。

Short tube throttle valve as a throttling device is widely used in household air conditioners because of its simple structure.When the refrigerant in two-phase state flows through the short tube throttle valve,serious noise is generated.In this paper,we designed and built a test bench for flow noise of short tube throttle valve,and experimentally studied the effect of refrigerant flow pattern,refrigerant mass flow rate and refrigerant quality on the frequency and sound pressure level of flow noise.The experimental results show that the sound pressure level of the flow noise is the largest when the valve inlet flow pattern is churn flow,and the flow noise is smaller when the valve inlet flow pattern is bubble flow and annular flow.The peak frequency of flow noise increases with the increase of mass flow rate.When the mass flow rate increases from 20 kg/h to 80 kg/h,the peak frequency of flow noise increases by 38.6%;when the refrigerant quality increases from 0.05 to 0.4,the average sound pressure level of flow noise firstly increases by 7 dB and then decreases by 3 dB.The optimized structural solution is proposed to reduce the average sound pressure level of flow noise by 2 dB by replacing the sudden contraction structure at the spool inlet with a flared and tapering structure.