Fuel combustion apparatus

A fuel combustion apparatus comprising an outer shell defining an enclosed hollow chamber, an inner shell composed of an upstream small-diameter section located within said chamber, a downstream large-diameter section extending in part outwardly of one end of said outer shell and a conically shaped connecting section between the two sections of different diameters, all said sections being aligned and connected together on a common axis and spaced from said outer shell, duct means extending through said outer shell for the supply of air to the space between said shells, a fuel injection valve and a first air supply port in communication with the space between said shells equipped with swirl blades surrounding the injection valve, said injection valve and air supply port being both provided at the upstream end of the small-diameter section of the inner shell, both the cylindrical wall of the small-diameter section and the conical wall of the connecting section of the inner shell being not perforated for air supply, second air supply ports in communication with the space between said shells formed in the cylindrical wall portion of the large-diameter section close to the connecting section, each of said second ports being shrouded with scoops extending at an angle into the large-diameter section at least perpendicularly to the direction of flow of said fuel, and means installed on the upstream side of the first air supply port for controlling the rate of air supply from said duct to the said first port whereby the flow of air supply to said first port relative to said second ports may be regulated.