spiral duct meaning in English

螺纹导管
螺旋导管
螺旋风管
螺旋式风道

Optimization study on single spiral duct condenser ' s structure parameter
单螺旋槽套管式冷凝器结构参数优化研究
Low - velocity ducts , high - velocity ducts , spiral ducts , flexible ducts , square ducts , circular ducts , upvc ducts , air curtains , etc . fans & dampers
低速喉、高速喉、旋式喉、软接喉、方型喉、圆型喉、胶风喉、风闸等fans & dampers风扇及节气闸