In-nozzle multi-phase flow patterns in flash boiling atomization and their impacts on external sprays
In-nozzle multi-phase flow patterns in flash boiling atomization and their impacts on external sprays
复制标题
DOI：
10.1007/s00348-023-03600-3
复制
发表时间：
2023-02
影响因子：
2.4
通讯作者：
Shangning Wang;Shuyi Qiu;Yijia Zhang;Mingli Cui;Xuesong Li;Min Xu
中科院分区：
文献类型：
--
作者：
Shangning Wang;Shuyi Qiu;Yijia Zhang;Mingli Cui;Xuesong Li;Min Xu
闪速沸腾雾化是一种很有前途的方法，可以产生具有较高蒸汽浓度的细液滴用于燃料燃烧。在闪蒸雾化中，气相被认为是提高雾化效率的关键因素，但其具体机理尚不清楚。典型的二维狭缝喷嘴测量可以揭示喷嘴内的过热流动特征，但放大的二维狭缝喷嘴无法近似描述体积特征。在这项工作中，我们制造了一个矩形的、光学可接近的喷嘴，其尺寸接近真实的喷油器喷嘴。采用单组分正戊烷燃料引发喷嘴内过热流动和连续闪沸喷雾。捕获了不同燃油温度和喷射压力下两相喷嘴内流动的微观和宏观特征。研究发现，瞬时沸腾过程中喷嘴内的流动模式与垂直管内沸腾过程相似。外喷雾雾化与喷嘴内两相流型密切相关。最后，提出了基于流型划分闪沸状态的新准则。图形抽象
Flash boiling atomization is a promising method to produce finer droplets with a higher vapor concentration for fuel combustion purposes. The vapor phase is regarded as a key component to enable better atomization efficiency in flash boiling atomization, but the exact mechanisms are missing. Typical two-dimensional slit nozzle measurements can reveal in-nozzle superheated flow characteristics, but volumetric features cannot be approximated by enlarged two-dimensional slit nozzles. In this work, we fabricate a rectangular, optical accessible nozzle with dimensions close to real fuel injector nozzles. The single-component fuel of n-pentane was used to trigger superheated in-nozzle flows and consecutive flash boiling sprays. Microscopic and macroscopic features of the two-phase in-nozzle flows were captured at different fuel temperatures and injection pressures. It is found that the flow patterns inside the nozzle during flash boiling are similar to those observed in vertical tube boiling flows. It is also observed that the external spray atomization is closely related to the in-nozzle two-phase flow patterns. Finally, new criteria for categorizing flash boiling regimes based on the flow pattern are proposed.Graphical abstract