蒸汽限流器结构对其阻力及流场细节的影响

Effect of the Structure of Steam Flow Limiter on Its Resistance and Flow Field Details

对2种蒸汽限流器的阻力性能和流场细节进行三维数值计算和流动分析。采用Realizable k-ε湍流模型结合标准壁面函数对设计的蒸汽限流器进行三维数值计算,研究结构参数对流场细节和阻力性能的影响。结果表明:随着入口流量增加,2种蒸汽限流器的阻力均上升,而阻力系数均保持定值,分别为4.95和3.05;19嘴限流器的阻力性能明显优于7嘴限流器;7嘴限流器的压力损失主要由回流区产生,达到总损失的71.4%,而19嘴限流器的压力损失主要由文丘里喷嘴和回流区产生,分别为总损失的50.5%和44.5%;19嘴限流器流场内的压力、速度和湍动能等参数比7嘴限流器更快达到稳定;对于7嘴限流器,其中心喷嘴流量是外部单个喷嘴流量的1.04倍;对于19嘴限流器,其中心喷嘴流量是外部单个喷嘴流量的1.18倍;19嘴限流器的外层喷嘴内存在回流区,因此可通过进一步优化19嘴限流器结构来改善其性能。

Three dimensional numerical simulations and flow analysis were carried out to study the resistance and flow field of the steam flow limiter adopted in a steam generator. The realizable k-e model with standard wall function was utilized to calculate the three-dimensional flow field of the flow limiter. The effect of the structure on the flow details and resistance was studied through analyzing the simulation results. The resistance of the flow limiter increases with the inlet mass flow rate while the resistance coefficient maintains constant, about 4.95 and 3.05 respectively. For the 7-nozzle flow limiter, the major pressure loss, about 71.4%, is caused by the backflow region, while for the 19-nozzle flow limiter, the major pressure loss is caused by the Venturi nozzles and the backflow region, about 50.5% and 44.5% respectively. The pressure, velocity and turbulent kinetic energy in the flow fields of the 19-nozzle flow limiter reach steady more rapidly than that of the 7-nozzle flow limiter. For the 7-nozzle flow limiter, the mass flow rate of the centric nozzle is 1.04 times that of the outer nozzle, while for the 19-nozzle flow limiter, the mass flow rate of the centric nozzle is 1.18 times that of the outer nozzle. The outer nozzle of the 19-nozzle flow limiter has backflow region in its diffuser, hence the performance of the 19-nozzle flow limiter could be improved through optimizing its structure.