摘要
汽轮机低压缸的湿蒸汽区液膜在高速汽流拖拽撕裂下形成较大水滴,会造成动叶片的严重水蚀,实时监测液膜厚度对于叶片防护及机组的安全运行具有重要意义。对此,搭建了谐振腔等效电路,并推导液膜厚度的测量关系式,设计了电磁性能良好的开式同轴谐振腔传感器,仿真分析了同轴腔的谐振频率随水膜厚度的变化关系,确定了测量关系式中的待定系数;选择蒸馏水为液膜材料,介电常数为81,利用电磁仿真软件HFSS计算水膜厚度h从0变化到1 mm,单位增加0.02 mm时进行拟合仿真,结果表明:拟合相似度0.995,均方根误差0.022。可见,该测量关系式可靠性较高,该测量技术可用于测量汽轮机静叶片、汽缸壁、导流环等结构处的液膜厚度。
Dragged by high speed steam flow,the water film at wet-steam region in steam turbine low pressure cylinder will form large droplets,causing serious water erosion of rotor blade. Real-time monitoring on liquid film thickness has great significance on rotor blade protection and unit safe operation. Thus,equivalent circuit of resonant cavity was built up. On this basis,the mathematical model of water film thickness measurement was established and the thickness measurement equation was deduced. The opening coaxial resonant cavity with good electromagnetic performance was designed. By using the HFSS software,the relationship between water film thickness and resonance frequency was analyzed,and the undetermined coefficients of thickness measurement equation were determined.Simulation on distilled water film whose dielectric constant is 81 shows that,when the water film thickness increases from 0 mm to 1 mm（ with step of 0. 02）,the fitting similarity is 0. 995 and the mean square error is 0. 022. Therefore,this measurement formula has high reliability,which can be used to measure the liquid film thickness for static blades,cylinder walls,guide rings and other places.
出处
《热力发电》
CAS
北大核心
2015年第3期99-103,共5页
Thermal Power Generation
基金
国家自然科学基金资助项目(51016044)
中央高校基本科研业务资助项目(13MS93)
关键词
汽轮机
液膜厚度
同轴谐振腔传感器
开放式
测量关系式
steam turbine
liquid film thickness
coaxial resonant cavity
sensor
open cavity
measurement correlation
