气液两相流波动系数及其在流型识别中的应用

Fluctuation coefficient of gas-liquid two-phase flow and its application in flow pattern identification

为了克服已有流型识别方法受主观影响大、在线识别困难和流型识别不准确等缺点，利用对气液两相流流型影响小、压力损失小的文丘里管测量差压信号．通过计算差压信号瞬时值平均方根与平均差压方根之间的比值得到气液两相流的波动系数，提出了双参数识别气液两相流流型的方法．波动系数表明了瞬时差压偏离平均差压的程度以及截面含气率的波动程度．两相流动越不稳定，截面含气率波动越大；气液两相流各截面状态的差异越大，波动系数越大．两相流波动系数表示两相流动的波动程度，使用波动系数可以直接将分层流与其他两相流流型区别开。试验结果表明，双参数识别气液两相流流型的方法受主观影响较小，可以有效识别泡状流、塞状流、弹状流、环状流和分层流．

Traditional flow pattern identification methods are inaccurate, irresistant to subjective influence and difficult in on-line identification. A new two-parameter method of identifying gas-liquid flow patterns was proposed. Differential pressure (DP) signals were measured by Venturi tube which had the minimum pressure loss in the throttling devices and little influence on flow patterns. The root of mean DP was divided by the mean root of instantaneous DP to obtain the fluctuation coefficient, which denoting the deviation between the instantaneous DP and the mean DP, and also denoting the fluctuation degree of void fraction. When the two-phase flow is in an unsteady state, the void fraction fluctuates largely, the state of differential section of two-phase flow has a large deviation, and the fluctuation coefficient is large. The stratified flow can be directly distinguished from other flow patterns by the fluctuation coefficient. Experimental results show that this two-parameter identification method can precisely identify the flow patterns including bubble flow, slug flow, plug flow, annular flow and stratified flow.