扩压管流道改型对汽轮机排汽缸流动的影响

Influence of the Diffuser Tube Shape Modification Design on the Flow of Steam Turbine Exhaust Cylinder

当容积流量减小时,排汽缸内的流动将偏离设计工况,静压恢复系数和总压恢复系数都将发生变化。基于国内外研究现状,联合末级全周建立了三维计算模型,设计了3种不同导流环倾角的扩压管流道,分析了100%、70%、40%等3种容积流量工况下排汽缸内的流动特性及涡系特点,得到了3种方案不同容积流量下的静压恢复系数及总压损失系数。研究表明:导流环倾角增加将抑制导流环附近漩涡的产生及发展,静压恢复效果显著,能量损失较原型有所减小。研究结果可为汽轮机排汽缸扩压管改型提供参考。

When the volume flow decreases,the flow in the exhaust cylinder will deviate from the design condition,and the static pressure recovery coefficient and the total pressure recovery coefficient will change.Based on the research status at home and abroad,a three-dimensional computational model is established in combination with the last stage,and three diffuser channels with different diversion ring inclination angles are designed.The flow characteristics and vortex system characteristics in exhaust cylinder under three volumetric flow conditions of 100%,70%and 40%are analyzed,and the static pressure recovery coefficients and total pressure loss coefficient s of three schemes under different volumetric flow rates are obtained.The results show that the vortices near the diversion ring will be inhibited by increasing the inclination angle of the diversion ring,and the hydrostatic recovery effect is remarkable.The energy loss is smaller than that of the prototype.The research results can provide reference for retrofitting the diffuser pipe of steam turbine exhaust cylinder.