yeah i spent a bunch of time puzzling over this same idea, it transfixed me for years
there are people who have made them
in theory i think
1) don't over think it- regular carberaters work really good as-is
2) part of the way carbs work is the air always sticks to the bottom of the hole, that way all the jets and stuff can work from the bottom up, you'd have to put an annular venturii in it like a butterfly car carburetor
3) if you need more flow just make it bigger
4 there is nothing magical about an annular opening, carbs like dirty turbulent air, breaks the fuel up better and gives you better mixing.