Tuyere

A tuyere or tuyère (French pronunciation: ​[tɥijɛʁ]; English /twiːˈjɛər/) is a tube, nozzle or pipe through which air is blown into a furnace or hearth.

Air or oxygen is injected into a hearth under pressure from bellows or a blowing engine or other devices. This causes the fire to be hotter in front of the blast than it would otherwise have been, enabling metals to be smelted or melted or made hot enough to be worked in a forge. This applies to any process where a blast is delivered under pressure to make a fire hotter.