基于AMESim的液氮供给系统液击仿真

基于系统级仿真平台AMESim，建立了大型低温风洞（CWT）液氮供给系统（LNSS）的动态仿真模型。实验对比结果显示，仿真结果的平均误差在6.8%以内，验证了模型的准确性，并进一步对比开展了喷嘴瞬时全关和喷嘴有序关闭两种典型工况下的液击分析。结果表明液击模型能够较好地反映管路系统中的液击过程。喷嘴瞬时全关工况下，液击峰值压力可达2.98 MPa；而当喷嘴分四组有序关闭时，液击峰值压力能有效降低，峰值压力为2.3 MPa且出现在最后一组喷嘴关闭时。同时，傅里叶分析（FFT）表明液击发生时压力波动存在一定周期性，且由多种频率组成，但喷嘴关闭模式对频率几乎没有影响。仿真研究结果可为大型低温风洞液氮供给系统提供设计校核和安全运行支撑。 

Simulation of water hammer in liquid nitrogen supplying system based on AMESim

A dynamic model of liquid nitrogen supplying system （LNSS） for a large cryogenic wind tunnel （CWT） was built based on the advanced modeling environment for simulation of engineering systems （AMESim） platform.The accuracy of the model was verified by the experimental data with the mean deviation less than 6.8%.Accordingly，numerical simulation on water hammer was carried out under two working conditions of instantaneously complete close-down and orderly close-down of the nozzles at the end of the LNSS.Numerical results illustrated that the dynamic model can characterize the features of water hammer in the complex LNSS.The peak pressure at water hammer reached 2.98 MPa under the condition of instantaneous close-down of all the nozzles.By contrast, the peak pressure reached maximum with the value of 2.3 MPa at the last close-down when the nozzles were shut down orderly following four steps.Moreover，fast fourier transform （FFT） analysis illustrated that different frequencies existed in the pressure fluctuations during water hammering.However, the frequencies showed inconspicuous distinct under these two working conditions.The simulation results provide a support for the design check and safe operation of the large CWT.