一种新型的预测射流扩散火焰长度、直径和体积的方法

摘要

对二甲醚、天然气、LPG射流扩散火焰的长度、直径及体积特性进行试验和理论研究,并探究了喷嘴内径df对火焰流动状态的影响.结果表明,随df的增加,火焰过渡区及吹熄极限对应的射流雷诺数Ref逐渐增加,而相应的射流速度uf逐渐降低.对每种燃料,其层流无量纲火焰长度与Ref呈正比,湍流无量纲火焰长度为定值;在层流和湍流状态下,火焰直径恒定,但在过渡区,火焰直径快速增加.据此,本文提出一种新型、预测精度更高的射流扩散火焰几何尺寸的关联式,并拟合出二甲醚、天然气、LPG火焰的无量纲长度、直径及体积的经验关联式.%In this paper,the length,width,and volume behavior of DME,natural gas and LPG jet diffusion flames were experimentally and theoretically studied.A series of fuel nozzles with different internal diametersdf were involved presently to investigate its effect on the flame behavior.The results show that with the increase of df,the transitional and bow-outRef increase,and the correspondinguf decreases gradually.For each fuel,the laminar dimensionless flame length is proportional to Ref,while the turbulent one remains unchanged.Besides, the dimensionless flame width remains unchanged at laminar and turbulent regimes,but it increases quickly at the transitional stage.Accordingly,new forms of correlation with higher prediction accuracy were developed to corre-late the dimensionless length,width and volume of DME,natural gas and LPG jet diffusion flames withRef.