Combined turborocket and ramjet propulsion unit

Abstract

A combined turborocket and ramjet propulsion unit comprises an air intake duct, and an air compressor with two counter-rotating rotor stages disposed downstream of the duct in an annular path formed between an outer casing and a central body which is maintained in position relative to the casing by structural arms. The rotor stages of the compressor are driven by a power turbine driven by combustion gases from a gas generator which burns liquid propellants. The power turbine includes two interleaved counter-rotating modules arraanged within the central body in a position longitudinally between the two compressor stages which they drive, and the gas generator is disposed axially within the central body to the rear of the turbine modules, the generator supplying the combustion gases to the turbine in an upstream direction through a central ejection chamber and an annular reversing chamber which redirects the gases rearwards through the turbine. The gases from the turbine are discharged into the compressed air stream at the rear of the central body and are subjected to afterburning before discharge through an exhaust nozzle. On changeover to ramjet operation the fuel supply to the gas generator is shut off and is directed instead to fuel injectors disposed in a combustion chamber located in the air flow path downstream of the compressor. The compressor blades are feathered and the fuel is burned in the combustion chamber with the air compressed in the air intake duct.