Through theoretical analysis and by establishing mathematical models,the numerical simulations for the sonic nozzles and their downstream pipelines with throat diameters of 10 mm and 0.96 mm were carried out by means of the CFD software respectively.The comparison of simulation results and empirical values and actual values are relatively consistent.According to the simulation results,pressure changes strongly from the nozzle outlet,the critical back pressure ratio changes with the straight pipeline length increasing;when the back pressure ratio is less than a certain value,the pressure in the downstream pipeline appears fluctuations in the nozzle outlet.%通过理论分析和建立数学模型,采用CFD软件,分别对喉径为10 mm和0.96 mm两种音速喷嘴及下游管路内的流场进行了数值模拟;对流出系数的模拟值、经验值和实际值进行了比较,三者的值较为吻合.模拟结果还发现,气体静压在喷嘴出口处波动比较剧烈;临界背压比随着下游管路长度的改变而有所变化;当背压比小于一定数值时,管路内的静压力将出现波动.
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