气液混输管线气相流量瞬态变化特性实验研究

在大型多相流实验环道上进行了气体流量快速变化的瞬态特性实验。结果表明 ,气体流量突变产生沿管线衰减传播的压力波 ,它在分层流中的传播速度大于其在段塞流中的传播速度。气体流量突变后 ,不同流型下其压力变化趋势相同。在气体流量突然增加的过程中 ,出现压力过增量 ;在气体流量突然下降过程中 ,出现压力过降量。但是 ,压力在两种流型中的瞬态变化机理不同 ,分层流中压力的瞬态变化取决于气体的惯性和可压缩性 ;段塞流中压力的瞬态变化过程则取决于液塞的惯性和液膜区气体的可压缩性。在气体流量瞬态变化过程中还可能出现对应准稳态过程未出现的流型。当气体流量突然增加时 ,在分层流的瞬态变化过程中可能出现段塞流 ,在段塞流的瞬态变化过程中会出现冲击性增强的高频段塞流 ;当气体流量突然降低时 ,在段塞流的瞬态变化过程中则会出现短时间的分层流。

Experimental study on transients characteristics of gas flow rate in gas-liquid pipelines

The transient behaviors of gas flow initiated by quick change of gas flow rate were tested on a big multiphase flow loop. The results demonstrate that the sudden change of gas flow rate leads to downstream propagation of pressure wave at a speed varying with flow pattern. For various flow patterns, the pressure evolution has the same tendency. However, the transient mechanism of pressure for different flow patterns is various. The transient process of pressure in stratified flow relies on the inertia and compressibility of gas, and that in slug flow relies on the compressibility of gas in liquid film zone and the inertia of liquid slug. In addition, there will appear certain temporary flow patterns different from the flow patterns of quasi-steady change. In up-gas transient state, unsteady slugs were found even though the initial and final states are in stratified flow. In the transient process of slug flow, intensified slugging with high frequency was found. When gas flow rate quickly decreases, there will appear a short period of stratified flow in the transient process of the slug flow.