Research on Flow Distribution in UTSG under Low Flow Rate Condition

The CFD method is used to study the flow characteristics in the primary side of a vertical,inverse U-bend tube steam generator in this paper.The study result shows that the reversal flow occurrs in the inner short tubes,with the structure data of the U tubes of the natural circulation simulation test facilities.With the low flow rate,when the inlet flow rate is increased,the reversal flow rate will be decreased,and the number of reversal flow tubes will be decreased as well,till it disappears.When the temperature in the second side is increased,the reversal flow rate will be decreased,and the number of reversal flow tubes will be decreased as well,till it disappears.