汽轮机调节阀-调节级段三维流动与压力损失数值研究

Numerical Investigations on 3D Flow Characteristics and Pressure Loss in Control Valves-Control Stage in Steam Turbine

部分进汽是喷嘴调节汽轮机变工况运行时的主要状态,调节级部分进汽通常效率较低,流动情况复杂。该文采用ANSYS-CFX软件数值研究了亚临界600MW汽轮机调节阀-调节级段在不同阀门开度组合情况下的三维流动与压力损失特性。结果表明:调节阀-调节级段的流动是复杂而强烈的有旋流动;调节阀喉部的节流作用和阀碟下方"空穴"区以及调节阀下游部分区域的漩涡会引起较大的压力损失;当4个调节阀全部开启时,调节阀-调节级段的流动性能良好,当某调节阀门处于关闭状态时,部分进汽调节级的动叶栅在从进汽弧段转到非进汽弧段过程中,动叶通道中的流体被抽吸到非进汽腔室以及对应的喷嘴叶栅中,形成大量的漩涡,造成较大的压力损失。

Partial admission is widely used in control stages of nozzle feed steam turbines under off-design conditions, which leads to low flow efficiency and complicated flow characteristics. The ANSYS-CFX software was used to numerically study the 3D flow characteristics and pressure loss in the region of control valves-control stage of a subcritical 600MW steam turbine. The results show that flow in calculation domain from the control valves to the control stage is complicated rotational flow. The throttling effect of the valve throat, the cavity under the valve disk, the swirls in the downstream of the control valve contribute a lot to the total pressure loss coefficient of the calculation domain. The stage has the best aerodynamic performance under the four valves fully open condition. However, under the conditions that valve closed, steam will be pumped into the non-admission steam rooms and the corresponding nozzle group when the rotor blades moving from the admission arc to the non-admission arc, which leads to notable swirls and total pressure loss in the partial admission stage.