The welding technology of francis turbine runners is optimized from the view of subsection welding and local heating by numerical simulation . the result shows that welding residual tensile stress appears in the weld and its area nearby , and peak stress appears in the dangerous area of blades after practising quondam welding technology ; welding residual tensile peak stress in the dangerous area of blades can be decreased by welding both ends earlier and then welding middle section later during subsection welding , and decreasing effect on welding residual stress of the subsection welding is related to the weld length of blade outlets and welding direction of each subsection ; decreasing effect on residual stress of the local heating is direct proportional to heating time , heating temperature , heating area , and inversely proportional to cooling area , and welding residual tensile peak stress in the dangerous area is decreasing trend earlier , and then increasing trend later with heated location increased 本文利用数值模拟手段对转轮的焊接工艺从分段焊和局部加热两个方面进行了优化,结果表明:采用普通工艺焊接时,叶片焊后残余拉应力出现在焊缝及其附近区域,并且在叶片出水边的熔合线附近(危险区域)出现了峰值;在采用优化的分段焊时,先焊两端后焊中间的方法可以降低叶片危险区域的焊接残余拉应力峰值,降低效果与叶片出水边焊段长度、焊缝各段的焊接方向有关;局部加热法降低转轮危险区域残余应力的效果主要与加热时间、加热温度以及加热面积成正比,与冷却面积成反比,并且危险区域的残余应力随加热区域的增大呈先降低后升高的趋势。
焊: weld; solder段长度: segment length层段长度: interval length层流段长度: laminar flow extent; laminar-flow extent成型段长度: land length程序段长度: program segment size; segment length反应段长度: reaction length管段长度: length of pipe section; length of the pipe河段长度: length of reach缓和段长度: length of runoff活性段长度: active length加速段长度: transition distance进口段长度: entrance length进流段长度: length of entrance爬高段长度: climb片段长度: rflp坡段长度: length of grade section; length of slope element起始段长度: entrance length切段长度: cut length区段长度: block length去流段长度: run length射孔段长度: perforation length试验段长度: working section length衰减段长度: attenuation distance梯段长度: go