扩压管出口结构对排汽缸气动性能的影响

摘要

采用Fluent软件对具有不同扩压管出口内导流环倾角β和出口宽度d 的排汽缸模型进行了模拟计算.结果表明：β＝75°为最佳值,与β＝0的排汽缸相比,其排汽缸压力损失降低了41．2 Pa；d＝1250 mm为最佳值,与d＝1100 mm的排汽缸相比,d＝1250 mm的排汽缸压力损失降低了16．8 Pa；在上半缸的扩压管出口下游处加装一系列挡板,能将强度较大的漩涡分割成为多个小漩涡,限制了漩涡的强度和范围；加装挡板的排汽缸较未加装挡板时损失降低了27．8 Pa.综合改造后的排汽缸用于某600 MW机组,使该机组排汽缸压力损失降低了69 Pa,全机有效焓降提高了0．08％.%Numerical simulation on exhaust hood model with different inner guide ring angles and widths at outlet of the diffuser was performed,by using the Fluent software.The results show that:the optimal inner guide ring angleβwas 75°,with which the pressure loss of the exhaust hood reduced by 41.2 Pa,compared with theβ=0°condition;the optimal outlet width d was 1 250 mm,with which the pressure loss dropped by 16.8 Pa,compared with the d=1 100 mm condition;adding a series of baffles at the exhaust hood down-stream can divide the vortex with heavier intensity into multiple weaker vortexes,thus to control the strength and range of the vortexes.After the dampers were installed,the pressure loss decreased by 27.8 Pa.Application of the retrofitted exhaust hood on a 600 MW unit indicated that,the pressure loss of the exhaust hood dropped by 69 Pa,and the effective specific enthalpy drop increased by 0.08%.