I'm about to take on my first infusion project, have been using prepreg and regular vacuum bagging to this point but this part is too big to fit in my oven. I'm confused as to how the resin flows from the spiral tubing into the reinforcement if the tubing is supposed to sit on top of the peel ply as all the tutorials say?

The peel ply is a fabric just like carbon so it will just flow straight through from the mesh and into the reinforcement.  Peel ply is just a much tighter weave.

HI

Ahhhhhhhh, so I don't have the right stuff then, I only have release film, gotcha! Thanks!

https://www.easycomposites.co.uk/peel-ply

One word of caution on the use of peel ply however.  I've been using 2-inch strips of peel ply on top of my resin inlet spiral tubing to assure that the vacuum doesn't suck the bagging material between the spirals, cutting off the flow of resin to the remaining length of spiral tubing.  This has worked great to retain the rigidity and integrity of the spiral tubing resin supply channel to the part, but last night I accidentally allowed my strips of peel ply to be placed between the resin inlet manifold and the spiral.  The result was that the peel ply essentially blocked the resin from entering the spiral tubing.  I managed to save the infusion of the part, but it took some quick action and a lot of luck as I did introduce a lot of air bubbles into the bag trying to remedy the problem.  Question:  I'm using Stretchlon 200 bagging film.  It's very thin and is easily sucked between the spiral tubing, so I worry that it could cut off the flow of resin.  Should I use a different bagging film, possibly something thicker to prevent needing to place peel ply on top of my spiral tubing to prevent this problem?

Yeh use something else, Strechlon is horrible for infusion. It's actually a waste anyway, as anywhere that the bag has stretched into position will actually relax again once the resin flows in and you lose full consolidation. These areas will then be large areas of bridging that will fill with resin. 

A little thing ive figured with peel ply is to think about the way you lay it when building your stack.

if you need to put strips in because of the complexity of the parts shape, run all your pieces of peel ply the same way so the red lines all go in the same direction.

it's around 50% easier to rip/remove when going with the red line and if you lay it with the lines running 90deg to each other it's a real bitch to get out.