Bellmouth Inlet
A flared inlet to a round duct or a fan, with a straight spigot: made in rings, each part of a cone, or in petals pressed to the curve. A flared entry to a round duct or a fan, the flare a quarter round or less, with a straight spigot to fit the duct: made in rings, each part of a cone, or in petals pressed to the curve.
How the bellmouth inlet is developed, with a worked example · Pipe ends and nozzles