Abstract: To have a better understanding of microscopic behavior of salting-out particles in a steam turbine,a high-pressure grade nozzle was employed in a supercritical steam turbine as a research object and simulated the distribution of salting-out particles in the flow field from a steam turbine nozzle using CFD-PBM method. The average diameter,component number and the concentration distribution of salting-out particles were obtained,respectively. The simulation results show that the salting-out particle diameter varied little near the nozzle entrance,while the particle diameter gradually increased along the flow direction,and the growth rate of the particle diameter slowed down gradually near the nozzle outlet. In addition,due to the salting-out particles interaction,the component number distribution of particles with 20μm diameter decreased gradually along the flow direction,while the component number distributions of particles with 80μm and 140μm diameters were opposite. A high component distribution with 20μm diameter particle existed in the suction side,and with 140μm diameter particle existed in the pressure side. From the suction side to the pressure side,the concentration of the salting-out particles gradually increased,and it eventually formed a high concentration area near the pressure side.

Key words: steam turbine nozzle, salting-out particles, population balance model, two-phase flow

摘要： 为深入了解汽轮机内盐析颗粒的微观行为，本文以某超临界汽轮机高压级喷嘴为研究对象，应用计算流体力学与群体平衡模型耦合方法，对汽轮机喷嘴内盐析颗粒在流场中的分布进行数值模拟研究，获得了盐析颗粒在喷嘴内的平均粒径、组分数及浓度分布规律。模拟结果表明：在喷嘴入口附近处盐析颗粒粒径仅发生微小变化，沿介质流动方向盐析颗粒不断长大，但在喷嘴出口截面附近处，颗粒长大的幅度又趋于平缓；此外，在盐析颗粒相互作用的影响下，20μm粒径颗粒的组分数分布沿介质流动方向逐渐减小，而80μm和140μm粒径颗粒则与其相反；20μm粒径颗粒在叶片的吸力面处组分数较高，而140μm粒径颗粒在叶片的压力面处组分数较高；盐析颗粒浓度从叶片吸力面到压力面逐渐增大，最终在压力面附近形成高浓度区。

关键词: 汽轮机喷嘴, 盐析颗粒, 群体平衡模型, 两相流