Gas turbine engine

A gas turbine engine, comprising:

• a cylindrical-shaped casing comprising a circular shoulder portion which extrudes axially outwards, and forms a casing opening to a first end, and a bottom plate sealing a second end of said casing on the opposite side;
• a heat exchanger comprising two spaced-apart divider walls which extend spirally inwards from an inner perimeter of said casing towards an inner chamber inside said casing, and a top plate spacing a gap with the shoulder portion of said casing, said two spaced-apart divider walls sealing both ends with the top plate and the bottom plate and forming spirally a compressed air passageway and a turbine exhaust gas passageway adjacent to each other throughout the heat exchanger;
• a combustor installed in the inner chamber of said casing comprising a main exhaust opening formed towards the first end, and a sidewall formed a plurality of air holes thereon;
• and
• a turbine engine rotor comprising a coaxial compressor rotor and a turbine rotor each having a plurality of blades, wherein the blades of compressor rotor are positioned towards said casing opening, and the blades of turbine rotor are positioned towards said main exhaust opening.