超临界二氧化碳射流计算模型的建立与射流特性分析

Building of calculation model for supercritical carbon dioxide jetting and analysis of jetting characteristics

超临界二氧化碳射流是开发天然气水合物、页岩气等非常规能源的一项新兴技术,射流计算和特性分析是该技术的理论基础。基于一维可压缩流动理论,考虑二氧化碳气体的真实性质,建立了超临界二氧化碳射流计算模型,并分析了工况参数对超临界二氧化碳射流特性的影响。研究结果表明,本文建立的超临界二氧化碳射流计算模型具有较高的计算精度,可适用于现场工艺参数优化和方案设计;提高喷嘴压降可以增加射流速度,但是对射流马赫数的影响不明显;随着入口温度的增加,射流速度和射流马赫数均有所增长;围压的升高抑制了射流速度的增加,且极大降低了射流马赫数;提高喷嘴压降和围压都使射流的性质向高密度不可压缩流体转化,而入口温度的增加使射流性质更趋向于低密度可压缩流体。本文研究成果可为超临界二氧化碳射流技术的现场应用和方案设计提供理论支撑。

The supercritical carbon dioxide jetting is an emerging technology applied in the field of the development of unconventional resources like natural gas hydrate and shale gas,theoretically based on jetting calculation and characteristic analysis.On the basis of one-dimensional compressible flow theory,a calculation model for supercritical carbon oxide jetting was built with consideration of the nature of carbon oxide,and the effects of working parameters on the jetting characteristics of supercritical carbon dioxide were analyzed.The research results indicate that the calculation model for supercritical carbon dioxide jetting is of a relatively high calculation precision and applicable to in-site optimization of technical parameters and project design;if the pressure drop at the nozzle is enlarged,the jet velocity can increase correspondingly,but no obvious effects are made on the Mach number;with the inlet temperature rising,both of the jet velocity and Mach number can have certain increases;the escalation of confining pressure inhibits the increase of jet velocity and much reduces the Mach number;the growing pressure drop at the nozzle and confining pressure can convert the fluid into high-density incompressible fluid,while the rising inlet temperature leads to low-density compressible fluid.The research results in the paper can provide theoretical support for the field application and plan design of supercritical carbon dioxide jetting technology.