单根螺旋管内沸腾两相流动不稳定性实验研究

Experimental Study on Boiling Two-Phase Flow Instability in a Single Helically Coiled Tube

加热通道内发生沸腾相变时会出现流动不稳定,研究螺旋管内沸腾两相流动不稳定过程对螺旋管式直流蒸汽发生器的设计和运行具有重要意义。本文通过在热工实验平台中开展单根螺旋管内的沸腾两相流动实验,研究螺旋管内发生沸腾两相流动时的流动不稳定现象,通过实验分析加热功率上升过程中螺旋管内流量压降等参数在不同时刻的变化规律以及频谱特征,并将发生的沸腾两相流动不稳定性进行分类。结果表明在实验参数范围:压力为0.1~3MPa、流量为300~1200kg/h、入口过冷度为20~100℃、实验段加热功率为0~200kW时,螺旋管加热通道内随着功率的增加会先出现流量漂移不稳定性,当流量漂移至另一流量值后,在低出口含汽率情况下会出现高频低振幅的密度波振荡,在高含汽率下会出现低频高振幅的密度波振荡。通过实验研究还发现入口过冷度、入口流量以及系统压力的增加均会提高系统的稳定性。

The boiling phase change happened in the heating channel will induce flow instability.Thus,studying the two-phase flow instability in helically coiled tubes is of great significance in the design and operation of helical-coil one-through steam generators.In this paper,the boiling two-phase flow experiment in a single helically coiled tube is carried out on the thermal experimental platform,and the flow instability phenomenon when boiling two-phase flow occurs in the helically coiled tube is studied.In the experiment,the boiling two-phase flow instability is classified by analyzing the variation and spectral characteristics of parameters such as flow rate and pressure drop in the helically coiled tube at different times during the rise of heating power.The results show that when the experimental parameters are in the range of 0.1~3 MPa for pressure,300~1200 kg/h for flow rate,20~100℃for inlet subcooling and 0~200 kW for heating power in the experimental section,the helically coiled tube heating channel exhibits flow drift instability as the power increases.Once the flow drifts to another flow value,low-amplitude high-frequency density wave oscillations occur under low steam quality conditions,while high-amplitude low-frequency density wave oscillations occur under high steam quality conditions.In addition,the increase of inlet subcooling,inlet flow rate and system pressure will improve the stability of the system.