接管布置方式对UTSG倒流现象的影响分析

蒸汽发生器进出口腔室的流场结构对倒流现象有重要影响,而进出口接管布置方式能改变其腔室流场结构。本文建立了两种不同接管布置方式蒸汽发生器三维模型,采用CFD方法模拟了其在低流量条件下的流动换热和流场结构,分析了接管布置方式对倒流现象的影响。研究结果表明:接管布置方式对腔室流动速度场产生显著影响,进而影响到U型管进出口压降和流量分配。适当改变接管布置方式可使流量分配不均匀性降低、U型管进出口负压降升高,从而使蒸汽发生器倒流发生的临界流量和倒流总流量降低。

Influence of Nozzle Arrangement on Reverse Flow Phenomenon in UTSG

The flow structure in plenum of steam generator has an important influence on the reverse flow phenomenon, and the inlet and outlet nozzle arrangements can change the flow structure in the plenum. In this paper, the three-dimensional models of steam generators with different nozzle arrangements were established. The flow structure and heat transfer in those steam generators were simulated under low flow rate condition. The effects of nozzle arrangements on reverse flow phenomenon were analyzed. The results show that the nozzle arrangement has significant influence on velocity field in plenum, and then affects the pressure drop and flow distribution of U-tube. If the nozzle arrangement is changed properly, the flow distribution will be more uniform and the negative pressure drop will increase, thus the critical flow rate of reverse flow and the reverse flow rate will decrease.