自然循环蒸汽发生器倒U型管内流动不稳定性判别准则

针对自然循环蒸汽发生器倒U型管内流动不稳定的特点,利用无量纲分析方法建立管内流体控制方程.采用小扰动分析方法,得到倒U型管内流动不稳定的判别准则.通过对某型蒸汽发生器进行计算分析,获得判别准则随流体进口温度和弯管半径变化规律.计算结果表明:随着流体进口温度的升高,特征雷诺数增加,但是不同流体进口温度条件下特征雷诺数随弯管半径的变化规律不同.相对于流体进口温度,弯管半径对特征雷诺数的影响较小.所得结论为蒸汽发生器倒U型管内倒流管空间分布及倒流流量计算提供理论依据.

Criteria of Flow Instabilities in Steam Generator U-Tubes with Natural Circulation

For flow instabilities in inverted U-tubes steam generator (SG),a dimensionless analysis is made for flow equation.Criteria of flow stabilities (characteristic Reynolds number) are derived according to small perturbation analysis.With calculation for a certain type of SG,effect of inlet fluid temperature and U-tube bend radius on the criteria are studied.It shows that the characteristic Reynolds number increases with the increase of inlet fluid temperature.Relations between U-tube bend radius under different inlet temperatures are complex.It is useful for calculation of flows as well as space distribution of reverse flow in a SG.