Study on Two-Phase Flow Instability in Helical Tube under Rolling Condition
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摘要: 螺旋管蒸汽发生器具有结构紧凑、换热能力强的优势，在反应堆的设计中应用越来越广泛，但运行在海洋条件下，其流动传热特征与直管流道式换热设备有差异，特别是在摇摆条件下的两相流动不稳定性，针对其试验研究尚不充分。本文针对单根螺旋管的两相流动不稳定性开展了静态和摇摆条件下的试验研究，研究了在不同加热功率水平下，其由单相流动过渡至密度波型脉动，进而过渡至压力降型脉动的过程。静止条件下在加热功率较低时，螺旋管内单相流动各参数波动范围在1%以内，当加热功率达到11 kW时产生了周期为4.4 s的密度波型脉动，当加热功率达到13 kW时，出现了周期约34.3 s的压力降型脉动。在摇摆条件下，摇摆运动与脉动产生了显著的复合效应，波动周期和幅值均发生了变化，通过对试验数据的研究和处理，获取了螺旋管内两相流动不稳定性的周期和频率等特征，揭示了引起其与直管流道中的两相流动不稳定性现象差异的机理，以及摇摆条件对两相流动不稳定性的影响机制。Abstract: Spiral-tube steam generator has the advantages of compact structure and strong heat exchange capacity, and it becomes increasingly prevalent in reactor design. However, its flow and heat transfer characteristics are different from those of straight-tube heat exchanges under marine conditions. Particularly, the instability of two-phase flow under rolling condition remains inadequately explored. In this study, the experimental study on the two-phase flow instability of a single helical tube is carried out under static and rolling conditions, and the process of its transition from single-phase flow to density wave pulsation and then to pressure drop pulsation under different heating power levels is studied. Under the static condition, when the heating power is low, the fluctuation range of each parameter of single-phase flow in the helical tube is within 1%. When the heating power reaches 11 kW, the density wave pulsation with a period of 4.4s is generated, and when the heating power reaches 13 kW, the pressure drop pulsation with a period of about 34.3s is generated. Under the rolling condition, the rolling motion and pulsation have a significant compound effect, and the fluctuation period and amplitude have changed. By studying and processing the experimental data, the characteristics of the period and frequency of the two-phase flow instability in the helical tube are obtained, and the mechanism that causes the difference between the two-phase flow instability in the helical tube and the straight tube flow channel is revealed, as well as the influence mechanism of the rolling condition on the two-phase flow instability.
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Key words:
- Helical tube /
- Rolling condition /
- Two-phase flow instability
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图 1 螺旋管内两相流动不稳定性试验回路示意图
T—温度测点；P—压力测点
Figure 1. Test Loop for Two-phase Flow Instability in Helical Tube
图 4 壁温热电偶周向布置示意图
Figure 4. Circumferential Arrangement of the Wall Temperature Thermocouples
图 5 单相流动状态下螺旋管内的流量与出口温度
Figure 5. Flow Rate and Outlet Temperature in Helical Tube under Single-phase Flow Condition
图 7 密度波型压降与流量变化
Figure 7. Variation of Pressure Drop and Flow Rate of Density Wave Pulsation
图 8 密度波型壁温与流量变化
Figure 8. Variation of Wall Temperature and Flow Rate of Density Wave Pulsation
图 9 压力降型流量与压降变化
Figure 9. Variation of Pressure Drop and Flow Rate of Pressure Drop Pulsation
图 10 压力降型流量与壁温变化
Figure 10. Variation of Wall Temperature and Flow Rate of Pressure Drop Pulsation
图 11 摇摆条件下流量与摇摆角度变化
Figure 11. Variation of Flow Rate and Rolling Angle under Rolling Condition
图 12 摇摆条件下壁温与摇摆角度变化
Figure 12. Variation of Wall Temperature and Rolling Angle under Rolling Condition
图 13 摇摆条件密度波型脉动流量变化
Figure 13. Variation of Flow Rate of Density Wave Pulsation under Rolling Condition
图 14 摇摆条件密度波型脉动压降变化
Figure 14. Variation of Pressure Drop of Density Wave Pulsation under Rolling Condition
图 15 摇摆条件压力降型脉动流量变化
Figure 15. Variation of Flow rate of Pressure Drop Pulsation under Rolling Condition
图 16 摇摆条件压力降型脉动壁温变化
Figure 16. Variation of Wall Temperature of Pressure Drop Pulsation under Rolling Condition
图 17 角加速度对界限功率的影响
Figure 17. Effect of Angular Acceleration on Instability Boundary Power
图 18 静态条件螺旋管通道流动不稳定性边界图
Figure 18. Flow Instability Boundary of Helical Tube under Stationary Condition
表 1 各测量参数不确定度
Table 1. Uncertainty of the Measurement Parameters
直接测量参数 不确定度 间接测量参数 相对不确定度/% 流体温度/℃ ±0.54 加热功率 ±0.72 加热元件壁温/℃ ±1.1 体积流量 ±0.63 压力/MPa ±0.0038 无量纲过冷数 ±0.35 压差/kPa ±0.025 无量纲相变数 ±1.0 
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表 2 摇摆条件下的试验工况参数
Table 2. Experimental Parameters under Rolling Condition
参数名称 参数范围 入口过冷度/℃ 10~60 流量/(m3·h−1) 0.1~0.5 系统压力/MPa 0.2~0.6 摇摆角度 10°~25° 摇摆周期T/s 10~40
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