Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this s...Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this study to recognize gas–liquid flow patterns by inducing fluid oscillation that enlarged differences between each flow pattern. Experiments with air–water mixtures were carried out in horizontal pipelines at ambient temperature and atmospheric pressure. Differential pressure signals from the bluff-body wake were obtained in bubble, bubble/plug transitional, plug, slug, and annular flows. Utilizing the adaptive ensemble empirical mode decomposition method and the Hilbert transform, the time–frequency entropy S of the differential pressure signals was obtained. By combining S and other flow parameters, such as the volumetric void fraction β, the dryness x, the ratio of density φ and the modified fluid coefficient ψ, a new flow pattern map was constructed which adopted S（1–x）φ and （1–β）ψ as the vertical and horizontal coordinates, respectively. The overall rate of classification of the map was verified to be 92.9% by the experimental data. It provides an effective and simple solution to the gas–liquid flow pattern identification problems.展开更多
水平管内流动冷凝的两相流型对其传热与流动的研究十分重要,流型图则是流型辨别及其转换判断的重要工具。本文总结了目前水平管内流动冷凝流型图及其转换标准的研究进展,列举了七种针对流动冷凝提出的流型图:Breber et al.(1980),Tandon...水平管内流动冷凝的两相流型对其传热与流动的研究十分重要,流型图则是流型辨别及其转换判断的重要工具。本文总结了目前水平管内流动冷凝流型图及其转换标准的研究进展,列举了七种针对流动冷凝提出的流型图:Breber et al.(1980),Tandon et al.(1982),Cavallini et al.(2002,2006),El Hajal et al.(2003),Kim et al.(2012)和Nema et al.(2014),根据现有的研究,发现目前的两相流型图大多针对绝热条件及流动沸腾所提出,其应用于流动冷凝中存在一定的偏差,而流动冷凝两相流型图目前研究还较少。另外,现有的流型图大多针对常规管道和基于常温常压工质所提出,其应用于微管道和低温或高压等工质存在一定的困难,且其研究还未能与传热及压降模型的研究实现较好的联系。展开更多
基金Project(51576213)supported by the National Natural Science Foundation of ChinaProject(2015RS4015)supported by the Hunan Scientific Program,ChinaProject(2016zzts323)supported by the Innovation Project of Central South University,China
文摘Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this study to recognize gas–liquid flow patterns by inducing fluid oscillation that enlarged differences between each flow pattern. Experiments with air–water mixtures were carried out in horizontal pipelines at ambient temperature and atmospheric pressure. Differential pressure signals from the bluff-body wake were obtained in bubble, bubble/plug transitional, plug, slug, and annular flows. Utilizing the adaptive ensemble empirical mode decomposition method and the Hilbert transform, the time–frequency entropy S of the differential pressure signals was obtained. By combining S and other flow parameters, such as the volumetric void fraction β, the dryness x, the ratio of density φ and the modified fluid coefficient ψ, a new flow pattern map was constructed which adopted S（1–x）φ and （1–β）ψ as the vertical and horizontal coordinates, respectively. The overall rate of classification of the map was verified to be 92.9% by the experimental data. It provides an effective and simple solution to the gas–liquid flow pattern identification problems.
文摘水平管内流动冷凝的两相流型对其传热与流动的研究十分重要,流型图则是流型辨别及其转换判断的重要工具。本文总结了目前水平管内流动冷凝流型图及其转换标准的研究进展,列举了七种针对流动冷凝提出的流型图:Breber et al.(1980),Tandon et al.(1982),Cavallini et al.(2002,2006),El Hajal et al.(2003),Kim et al.(2012)和Nema et al.(2014),根据现有的研究,发现目前的两相流型图大多针对绝热条件及流动沸腾所提出,其应用于流动冷凝中存在一定的偏差,而流动冷凝两相流型图目前研究还较少。另外,现有的流型图大多针对常规管道和基于常温常压工质所提出,其应用于微管道和低温或高压等工质存在一定的困难,且其研究还未能与传热及压降模型的研究实现较好的联系。
