Solid fuel afterburner and method of using the same to improve thrust and starting capabilities of a turbojet engine

Abstract

A turbojet engine includes a housing having a forward inlet nozzle, an aft exhaust nozzle, a combustion chamber therebetween, a compressor between the inlet nozzle and the combustion chamber, and a turbine between the combustion chamber and the exhaust nozzle. A liquid fuel injector is provided to inject atomized or vaporized fuel into the chamber for combustion therein. In addition, a solid fuel is provided in the aft exhaust nozzle. The solid fuel may be used to assist the starting of the engine, particularly useful under adverse starting conditions. That is, when the compressor begins to spin up to pump air through the engine, the solid fuel in the exhaust nozzle is ignited by an igniter which begins to combust with the oxygen rich air introduced by the compressor. This combustion increases the temperature in the entire engine, such that when liquid fuel is injected in the combustion chamber, the temperature is sufficiently high to allow the liquid fuel to burn in a self-sustaining manner. Thus, the engine is ignited from the back, and after ignition, the solid fuel continues to burn providing an afterburner effect boosting the thrust until the solid fuel is depleted. Alternatively, the solid fuel can be ignited after the liquid fuel is undergoing a self-sustained burn to provide an afterburner effect.