基于二氧化碳工质的回热器振荡流实验与模拟研究

Experimental and simulation study of oscillating flow in regenerator using carbon dioxide as working fluid

采用二氧化碳气体作为斯特林发动机内部循环工质可以实现机器长时间运行,降低成本。为探究二氧化碳工质在回热器中的流动特性,完善斯特林循环分析方法,更好地设计和优化基于二氧化碳工质的斯特林发动机,本文基于CFD方法建立了有限体积模型和振荡流模型,并搭建了振荡流实验台进行实验验证,获得了二氧化碳在金属丝网回热器中的压降、摩擦特性和流阻关联式。随后发现热吹和冷吹过程中流阻关联式的差异较大,在高雷诺数下(1733<Re<3587)二氧化碳和空气流阻关联式差异小于10%,在低雷诺数下(Re<1733)两者相差超过10%。此外,对二氧化碳工质循环率进行了修正,拟合得到了循环率与频率和目数的定量关系式。该流阻关联式和循环率可为优化回热器设计、完善斯特林循环分析方法提供理论支持。

Carbon dioxide is potential work media of Stirling engine for long-term running and low operating cost.To analyze the characteristics of carbon dioxide flowing in the regenerator of Stirling engine,improve the Stirling cycle analysis method,and better design and optimize the Stirling engine based on carbon dioxide,a finite volume model and an oscillating flow model are established based on the CFD method,and an oscillating flow experimental bench is established for verification to obtain the pressure drop and friction characteristics and flow resistance correlation of carbon dioxide in the wire mesh regenerator.It is found that,there is a large difference in the flow resistance correlation between the hot and cold blowing processes.The difference of flow resistance factor of carbon dioxide and air is less than 10%at high Reynolds number(1733<Re<3587)but greater than 10%at low Reynolds number(Re<1733).In addition,the cycle rate is corrected when carbon dioxide is used as working media,and a quantitative correlation is derived to describe the relationship of cycle rate,frequency and mesh number.The flow resistance correlation and cycle rate provide theoretical support for optimizing the design of the regenerator and improving the Stirling cycle analysis method.