水平管内流型转换区湿气流经多孔板的压降特性

较之于传统的单孔板,多孔板有压损系数小、整流、低噪声等多方面优点,在湿气流量测量中具有重要应用价值。以空气和水为两相工质,在水平管内湿气流型转换区对小孔分别呈圆形和矩形的2个多孔板的压降特性进行了实验。结果表明:圆孔、槽孔多孔板的湿气压降特性无明显差别;多孔板的气相压降倍率与气相、液相弗劳德数均密切相关;与实验结果相比,现有均相流模型的预报结果均偏高,现有分相流模型的预报结果均偏低;通过气相、液相弗鲁德数双参数对孔板湿气压降模型进行修正,可明显提高压降关联式的预报准确度;基于均相流模型双参数修正所得的多孔板压降关联式的预报精度最优,对圆孔多孔板、槽孔多孔板的预报偏差分别在±7%、±10%以内。

Wet Gas Pressure Drop Across Multi-orifice Plates in Horizontal Pipes in the Region of Flow Pattern Transition

Compared with the traditional single-orifice plate, multi-orifice plates have important application value in wet gas measurement because of its homogenizing the fluid, low noise, low pressure loss and other advantages. In this study, the pressure drop characteristics of two multi-orifice plates, having 48 round holes and 48 slotted holes, respectively, were tested in a horizontal pipe using air and water as the two phases and letting the inflow in the region of flow pattern transition. The results show that there is little difference between the round-hole and slotted-hole multi-orifice plates regarding wet gas pressure drop characteristics. However, it is found that the gas phase multiplier of orifice plates is closely related with variations in the Froude numbers of gas phase and liquid phase. Compared with the experimental pressure drop results, the existing homogenous flow models for orifice pressure drop present an overestimation whereas the existing separated flow models for orifice pressure drop exhibit an underestimation. By correlating the two parameters, i.e. the Froude numbers of gas phase and liquid phase, prediction accuracies of the pressure drop correlation for multi-orifice plates can be improved markedly. Among them, the proposed pressure drop correlation that is derived from a correction of the homogeneous flow model for orifice pressure drop using abovementioned two parameters is optimal in term of prediction accuracies, showing prediction accuracies within ±7% and ±10%, respectively, for the round-hole and slotted-hole multi-orifice plates.