熔盐堆旋叶式气水分离器工作特性数值分析

Numerical study on the performance of a vane-type bubble separator for molten salt reactor

本文以熔盐堆脱气系统中旋叶式气泡分离器为研究对象,利用数值分析软件Fluent对分离器内的流场进行了数值模拟,并分析了其工作原理和影响因素。首先,不同的湍流模型计算结果与实验现象的对比分析表明,雷诺应力模型在不同工况下计算得到的流场分布与实验现象符合最好。在确定适合用于模拟旋叶式气泡分离器内流场的计算模型基础上,对分离器内流场作进一步的计算分析。结果表明,水在流量20 m3·h-1条件下,流经分离器搅浑叶片后,会形成一种中心低速低压的旋转流动,且在横截面中心区域附近存在很大的径向压降梯度,如果水流中存在少量气泡,便会在压力梯度的作用下,流向分离器中心,汇聚形成稳定的气芯,从而实现对流体中气相的连续分离。

Background： The flow field in the vane-type bubble separator in the gas removal system developed for Molten Salt Reactor （MSR） was obtained by the Computational Fluid Dynamics （CFD） software of Fluent. Purpose： On the basis of the single phase water simulation, analysis was also conducted on the principle of the bubble separator as well as the factors affecting its performance. Methods： Firstly, different turbulence models were compared against the experimental data, among which the Reynolds Stress Model gave the best results under different working conditions. Then, by using of this model, further researches on the flow field in vane separator were carried out. Results： It is indicated that the water flow with low velocity and low pressure forms rapidly in the central area after flowing through the swirl vanes of the separator at the volume flow of 20 m3-h-1, and a high radial pressure gradient appears near the center of the cross section. Conclusion： As a result, if there are some bubi^les in the flow, they will be pushed to the center of the separator and merge to form a steady air core due to the large radial pressure gradient, leading to the continuous separation of bubbles from the water flow.