Picture Source Website (it's in Czech). Thanks to Jan Hudec for finding it.
My understanding of centrifugal engines is that they have larger diameters and therefore larger nacelle drag, and therefore aren't favored.
So in this question, I want to ask, are centrifugal engines less efficient internally? That is, for a given thrust at given conditions, will the centrifugal have more, less, or equal fuel consumption than a "normal" axial-flow engine?
I can't imagine that friction of air flowing around a winding path, or related viscuous effects, could amount to any noticeable penalty. But I can't think of any other reason why centrifugals would be internally less efficient.
Note, another related question, one answer did say that centrifugal compressors will have higher losses than axial compressors, for a given compression ratio, but did not explain why.