Cavity device of water-driven no-power exhaust fan

The invention discloses a cavity device of a water-driven no-power exhaust fan. The cavity device comprises a housing; a water inlet supercharging assembly is arranged at one end of the housing; and the other end of the housing is provided with a water outlet. The cavity device is characterized in hollow cavities are arranged in the housing, wherein the hollow cavities, namely a left cavity and a right cavity are packaged and surrounded on the housing; a spacing is set between the left cavity and the right cavity; and the left cavity and the right cavity are simultaneously mounted in the water inlet supercharging assembly and the water outlet. Circulating fire-fighting water in a ship body is circulated to drive an impeller to rotate; the fire-fighting water is firstly supercharged by the water inlet supercharging assembly, and secondly, the hollow cavities adopt shape designs of different sizes, so that the water pressure size is further increased; and reverse-direction impact is carried out on a curved-surf