To make it simple (and actually, directly relevant to what I am working on): what impact does winding tightness have on transformer performance? Lets assume typical laminated EI / EE 60hz transformer, operating at 60hz, within the maximum flux density of the core material.
I suppose this is also a good way to illuminate the oft-mentioned qualitative idea of the "flux capturing" effect of a high permeability core versus air. If most of the flux is in that core, then who cares if there is a little more air, right? But...imagining that holding as "loosely wound" approached infinite diameter seems..shaky.
For instance, so I have a transformer where the primary is wound tight on the core, and another, where the primary is the diameter of the solar system, and because they both encircle the same flux in that core, there is no change in performance? That can't be, right?
So I am imagining leakage inductance probably increases. But, physically, why that is (mental model), doesn't seem to be sinking in. Is it simply because the more air there is inside the turns, the more paths there are for the magnetic circuit? And its as simple as that? I'm imagining actually calculating the flux in the air part of the circuit is probably not trivial, but is that the mental model?
What would be really handy is an engineering type mental model explanation, and then maybe a little mention of why Maxwells equation makes it so.
EDIT: I just realized that the "air part of the circuit" is a little ambiguous. What I mean is, as the additional area inside the turn which is not the core containing the transformer/mutual inductance flux goes up, the ability of that turn to store energy goes up (air core inductor)..i.e. leakage inductance.
Separately is the question of increased mutual inductance, i.e. transformer action through the air, but lets pretend that the secondary winding is always wound tight..for the moment. (or compare/contrast wound tight or also increasing)