Abstract: A multiphase fuel injector has an injector body with a fuel inlet at a first end and a fuel outlet at a second end opposite the first end. A primary circuit disposed proximate the fuel inlet extends into a central portion of the injector body. The primary circuit is configured to receive a first flow of pressurized fuel from the fuel inlet that discharges into a spin chamber in the injector body downstream from the fuel inlet. The primary circuit is configured to impart a swirling action to the first flow of pressurized fuel. A secondary circuit is located in the injector body radially outward from the primary circuit. The secondary circuit is configured to receive a second flow of pressurized fuel from the fuel inlet that discharges into the fuel outlet. The secondary circuit is configured to impart a swirling action to the second flow of pressurized fuel.