文氏管出口张角对旋流杯性能的影响研究

Effects of Venturi Divergence Angle on Characteristics of Swirl Cup

关键词:  旋流杯  文氏管  综合性能  预膜式雾化  预估公式

Key words:  Swirl cup  Venturi  Comprehensive characteristics  Prefilming atomizing  Empirical correlation

摘要:

为了研究文氏管出口张角对旋流杯综合性能的影响，对不同文氏管出口张角的双级旋流杯开展了流量特性、下游流场和雾化性能试验，并借助仿真对试验结果进行了分析。结果表明：文氏管出口张角对旋流杯流量以及流量系数无显著影响。回流区外侧扩张锥面轴向速度随出口张角的增大先增后减。出口张角的存在可增大文氏管出口湍动能，强化两级旋流气体之间相互剪切作用进而改善雾化性能，存在一个最佳的角度（本文研究参数范围内，该值为56°）使得液雾平均粒径最小且液滴尺寸分布最均匀。拟合了关于文氏管结构的可用于预估双级旋流杯SMD值的模型公式，预估值与试验值吻合较好，相对误差小于20%。

Abstract:

In order to investigate the effects of venturi divergence angle on the comprehensive characteristics of swirl cup, experimental investigation of flow rate, downstream flowfield and spray characteristics were conducted for dual swirl cups with different venturi divergence angles. Meanwhile, the experimental findings were analyzed by means of simulation. The results indicated that venturi divergence angle has no significant effect on flowrate or discharge coefficient of swirl cup. The axial velocity of the swirling flow divergent angle zone outside of the recirculation zone increases initially and decreases afterwards with the increase of divergence angle. Venturi divergence angle can increase the turbulence kinetic energy, enhance shear of the primary and secondary swirl air, which can improve the atomization quality. There is an optimum divergence angle value (within the range of parameters studied in this paper, the divergence angle is 56°) for minimum mean drop size and uniform drops distribution in the spray. Empirical predictive correlation relating to the venturi structure was obtained to predict SMD for dual swirl cup, and the predicted values are in good agreement with the measurements with a relative error less than 20% of the present test range.