A power device comprises a spiral gas flow passage realizing a combination of axial flow and circumferential flow. The spiral gas flow passage comprises an intake section (9a), an intermediate section (10a), and an exhaust section (11a). When the spiral gas flow passage rotates about an axis, external air is drawn into the intake section (9a) and enters the intermediate section (10a) after total pressure is elevated. Fuel is mixed with the air in the intake section (9a) or the intermediate section (10a). The intermediate section (10a) comprises a combustion chamber which combusts the fuel and forms a high temperature and high pressure fuel gas. The fuel gas expands and performs work in the exhaust section (11a), and then the fuel gas is exhausted to the outside environment. The force performing work may be decomposed into an axial force and a tangential force or may be only a tangential force. The axial force is output as a push force, and the tangential force is output as a torque and drives the spiral gas flow passage to rotate about the axis. By the design of the spiral gas flow passage, the force performing work can have a reasonable distribution in the axial direction and the tangential direction. A combustion chamber liner and a power assembly are further provided.