In a fluid handling apparatus a bladed interrupter structure adapted for pointwise interruption of the boundary layer of a fluid flow at {HEAD ~ an apparatus surface} or surfaces of {TAIL ~ the apparatus} immediately adjacent to the interrupter structure, the said structure comprising: 
of
In a fluid handling apparatus a bladed interrupter structure adapted for pointwise interruption of the boundary layer of a fluid flow at { HEAD ~ an apparatus surface } or surfaces of { TAIL ~ the apparatus } immediately adjacent to the interrupter structure , the said structure comprising :
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