【摘要】 在小质量流速和流动沸腾条件下,对R134a工质垂直向上横掠水平光滑管束的汽液两相流型进行了实验研究,实验的质量流速范围为4~25 kg/(m2.s),质量干度范围为0.02~0.90.通过对各流型下的压差脉动信号进行离散小波分析,得到了各流型下压差脉动信号的尺度能量分布特征,并以尺度能量分布为特征矢量建立了流型辨识的规则.研究结果表明,该方法能够较好地鉴别泡状流、块状流和环状流3种主要流型.更多还原

【Abstract】 This paper presented a wavelet-transform based approach for flow pattern identification in horizontal tube bundles under vertical upward cross-flow condition. Tests on two-phase flow patterns of(R134a were) conducted under low mass velocity and flow boiling conditions over the ranges of mass flux 4～25(kg/(m~2·s),) vapor quality 0.02～0.90.Time series of differential pressure fluctuations were measured and analyzed with discrete-wavelet transform.Different time-scale characteristics in bubbly flow,churn flow and annular flow were obtained.The wavelet energy distributions over scales are found to be appropriate for flow pattern identification.Based on the characteristic vector of wavelet energy distribution over scales,a criterion of flow pattern identification was proposed.The comparison with experimental results shows that it is feasible to use the discrete wavelet transform as the tool of flow pattern identification in horizontal tube bundles under vertical upward cross-flow condition.更多还原