超临界二氧化碳超声速喷管设计与性能分析

Design and performance analysis of supercritical carbon dioxide supersonic nozzle

关键词:  超声速喷管  特征线法  超临界二氧化碳  真实气体效应  性能分析

Key words:  Supersonic nozzle  Method of characteristics  Supercritical carbon dioxide  Real gas effect  Performance analysis

摘要:

超临界二氧化碳由于其独特的物理性质而受到广泛应用。同时超临界二氧化碳真实气体效应显著，其流动机理和理想气体差别较大，因此需要设计相应的喷管。采用特征线法设计超临界二氧化碳超声速喷管，其中二氧化碳的热力学参数基于S-W方程获得。通过CFD粘性仿真进行边界层修正。分析了改变喷管入口总压、总温对喷管内流场的影响。结果显示，设计工况下喷管出口质量平均马赫数与设计值相差0.033%，喷管内流场品质较好；非设计工况下，由于温度变化会显著改变CO₂的热物性参数，入口总温对喷管流场的影响比总压更大，当入口总压和总温分别降低83.33%，52.94%时，出口马赫数分别降低1.16%、提高3.23%。设计工况下喷管流场满足设计要求，非设计工况下喷管出口马赫数与设计值偏差较小。喷管具有较宽的工作域。

Abstract:

Supercritical carbon dioxide is widely used due to its unique physical properties. The real gas effect of supercritical carbon dioxide is significant， and its flow mechanism is quite different from that of ideal gas， so it is necessary to design corresponding nozzles. The supercritical carbon dioxide supersonic nozzle was designed using method of characteristics，in which the thermodynamic parameters of carbon dioxide were obtained based on the S-W equation. The nozzle contour was corrected for boundary layer effect based on CFD viscous simulation. The effects of changing the total pressure and total temperature at the nozzle inlet on the flow field in the nozzle were analyzed. The results show that under design condition， the difference between mass-average Mach number and the design value at the nozzle outlet is 0.033% and the flow field quality in the nozzle is good. Under off-design conditions， because the change in temperature will significantly change the thermophysical parameters of CO₂， the effect of inlet total temperature on nozzle flow field is greater than that of inlet total pressure. When the inlet total pressure and temperature are reduced by 83.33% and 52.94% respectively， the Mach number at nozzle outlet decreases by 1.16% and increases by 3.23% respectively.The flow field in the nozzle meets the design requirements under the design condition， and the deviation between Mach number at nozzle outlet and design value is small under off-design conditions. Therefore， the nozzle can work under a wide range of conditions.